1.1.5
Copyright © 2012, 2013 Phil Whineray <phil@sanewall.org>
Table of Contents
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The latest version of this document will always be available here. There are PDF and HTML versions.
This manual is aimed at those who wish to create and maintain firewalls with Sanewall.
There is a lack of basic and tutorial information currently. Sanewall is a fork of FireHOL and its documentation can be used to learn the configuration language. See the FireHOL website.
The Sanewall website.
The mailing lists and archives.
The package comes with a complete set of manpages, a README and a brief INSTALL guide.
Table of Contents
RFC 4890 is entitled "Recommendations for Filtering ICMPv6 Messages in Firewalls".
The recommendations pertain to firewalling at router level, not necessarily hosts or bridges (which may need to treat some packets differently, e.g. NS/NA and RS/RA).
The sections below were extracted from the example implementation; each one describes how the recommendation can be achieved with Sanewall.
It is assumed that a policy of reject or deny is in place. If that is not the case then some packet types need dropping explicitly to meet the recommendations.
The router command (see router definition: sanewall-router(5)) should be used with an appropriate src rule parameter (see optional rule parameters: sanewall-rule-params(5)).
The ping - Ping (ICMP echo) - complex service should be used in combination with an appropriate dst rule parameter (see optional rule parameters: sanewall-rule-params(5)).
This is handled automatically by the ping - Ping (ICMP echo) - complex service .
The router command (see router definition: sanewall-router(5)) should be used with an appropriate src and dst rule parameter (see optional rule parameters: sanewall-rule-params(5)). For example:
src not "${UNROUTABLE_IPS}" dst not "${UNROUTABLE_IPS}"
The ping - Ping (ICMP echo) - complex service can be used with an appropriate src rule parameter (see optional rule parameters: sanewall-rule-params(5)). For example:
ipv6 route ping src not "${MULTICAST6_IPS}"
will prevent incoming echo-requests from multicast IPs and replies to them.
Ensure any routers have:
server ipv6error accept
Adding dst "$inner_prefix" ensures only public hosts receive the messages. See ipv6error - ICMPv6 Error Handling - complex service .
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
Note: in the example RFC script, non-established/related messages are allowed through for this type.
It is not clear why since code 0 and not code 1 messages are listed as part of the establishment of communications. Code 1 messages are listed as less essential for propagation over the network.
The behaviour implemented here is as per destination unreachable messages, so the same as the incoming time exceeded code 0 messages example.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
The rule(s) suggested by the section called “Allow incoming destination unreachable messages only for existing sessions” will also meet this recommendation.
From the RFC it is not really necessary to allow these messages. Sanewall handles this automatically (by dropping them) unless you set up an explicit route for the packets using the icmpv6 type bad-header.
Sanewall handles this automatically unless you set up an explicit route for the packets.
Hosts and bridges need to allow these messages. See ipv6neigh - IPv6 Neighbour discovery - complex service .
Sanewall handles this automatically unless you set up an explicit route for the packets.
Hosts and bridges need to allow these messages. See ipv6router - IPv6 Router discovery - complex service .
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type redirect -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 130 -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 131 -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 132 -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 143 -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 138 -j DROP
Sanewall handles this automatically unless you set up an explicit route for the packets.
At some point Sanewall may have a helper command added to simplify allowing these messages on a host/bridge. Meantime this is an example of the relevant ip6tables command:
ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 139 -j DROP ip6tables -A icmpv6-filter -p icmpv6 --icmpv6-type 140 -j DROP
At some point Sanewall may have a helper command added to simplify this setup. Meantime this is an example of the relevant ip6tables commands from the RFC script:
#incoming Home Agent address discovery request
ip6tables -A icmpv6-filter -p icmpv6 -d $inner_prefix \
--icmpv6-type 144 -j ACCEPT
#outgoing Home Agent address discovery reply
ip6tables -A icmpv6-filter -p icmpv6 -s $inner_prefix \
--icmpv6-type 145 -j ACCEPT
#incoming Mobile prefix solicitation
ip6tables -A icmpv6-filter -p icmpv6 -d $inner_prefix \
--icmpv6-type 146 -j ACCEPT
#outgoing Mobile prefix advertisement
ip6tables -A icmpv6-filter -p icmpv6 -s $inner_prefix \
--icmpv6-type 147 -j ACCEPT
At some point Sanewall may have a helper command added to simplify this setup. Meantime this is an example of the relevant ip6tables commands from the RFC script:
#outgoing Home Agent address discovery request
ip6tables -A icmpv6-filter -p icmpv6 -s $inner_prefix \
--icmpv6-type 144 -j ACCEPT
#incoming Home Agent address discovery reply
ip6tables -A icmpv6-filter -p icmpv6 -d $inner_prefix \
--icmpv6-type 145 -j ACCEPT
#outgoing Mobile prefix solicitation
ip6tables -A icmpv6-filter -p icmpv6 -s $inner_prefix \
--icmpv6-type 146 -j ACCEPT
#incoming Mobile prefix advertisement
ip6tables -A icmpv6-filter -p icmpv6 -d $inner_prefix \
--icmpv6-type 147 -j ACCEPT
Table of Contents
sanewall — an easy to use but powerful iptables stateful firewall
sanewall
sudo -E sanewall panic [
IP
]
sanewall command [
--
conf-arg...
]
sanewall CONFIGFILE
[ start | debug | try ]
[
--
conf-arg...
]
Running sanewall invokes iptables(8) to manipulate your firewall.
Run without any arguments, sanewall will present some help on usage.
When given CONFIGFILE,
sanewall will use the named file instead of
/etc/sanewall/sanewall.conf as its configuration.
If no command is given, sanewall assumes
try.
It is possible to pass arguments for use by the configuration file
separating any conf-arg values
from the rest of the arguments with --. The
arguments are accessible in the configuration using standard
bash(1) syntax e.g. $1, $2, etc.
Sanewall is a fork of FireHOL. existing FireHOL configurations should be compatible with Sanewall, but please see the section called “Compatibility” for any differences in behaviour.
To block all communication, invoke sanewall with
the panic command.
Sanewall removes all rules from the running firewall and then DROPs all traffic on all iptables tables (mangle, nat, filter) and pre-defined chains (PREROUTING, INPUT, FORWARD, OUTPUT, POSTROUTING).
DROPing is not done by changing the default policy to DROP, but by adding one rule per table/chain to drop all traffic. This allows systems which do not reset all the chains to ACCEPT when starting to function correctly.
When activating panic mode, Sanewall checks
for the existence of the SSH_CLIENT shell environment
variable, which is set by ssh. If it finds this, then
panic mode will allow the established SSH connection specified in this
variable to operate.
In order for Sanewall to see the environment
variable you must ensure that it is preserved. For sudo
use the -E and for su omit the
- (minus sign).
If SSH_CLIENT is not set, the IP after
the panic argument allows you to give an IP address for which all
established connections between the IP address and the host in panic
will be allowed to continue.
Activates the firewall configuration from
/etc/sanewall/sanewall.conf.
Use of the term restart is allowed for
compatibility with common init implementations.
Activates the firewall, waiting for the user to type the word
commit. If this word is not typed within
30 seconds, the previous firewall is restored.
Stops a running iptables firewall by clearing all of the tables and chains and setting the default policies to ACCEPT. This will allow all traffic to pass unchecked.
Restarts the Sanewall firewall only if it is already active. This is the generally expected behaviour (but opposite to FireHOL and Sanewall prior to 1.0.3, 1.1.4).
Shows the running firewall, using /sbin/iptables -nxvL | less.
Start the firewall and then save it using
/sbin/iptables-save to
/etc/sysconfig/iptables.
The required kernel modules are saved to an executable shell
script /var/spool/sanewall/last_save_modules.sh,
which can be called during boot if a firewall is to be restored.
External changes may cause a firewall restored after a reboot to not work as intended where starting the firewall with Sanewall will work.
This is because as part of starting a firewall, Sanewall checks some changeable values. For instance the current kernel configuration is checked (for client port ranges), and RPC servers are queried (to allow correct functioning of the NFS service).
Parses the configuration file but instead of activating it, Sanewall shows the generated iptables statements.
Enters an interactive mode where Sanewall accepts normal configuration commands and presents the generated iptables commands for each of them, together with some reasoning for its purpose.
Additionally, Sanewall automatically generates a configuration script based on the successful commands given.
Some extra commands are available in explain mode.
Special commands in explain mode
Present some help
Present the generated configuration
Exit interactive mode and quit
The iptables_cmd outputs generated by Sanewall refer to a function which detects and makes use of IPv4 or IPv6 functionality automatically. The function is nearly but not quite identical to iptables(8) so please take care if using the output elsewhere.
Tries to guess the Sanewall configuration needed for the current machine.
Sanewall will not stop or alter the
running firewall. The configuration file is given in the standard
output of sanewall, thus
sanewall helpme > /tmp/sanewall.conf
will produce the output in /tmp/sanewall.conf.
The generated Sanewall configuration must be edited before use on your systems. You are required to take a number of decisions; the comments in the generated file will instruct you in the choices you must make.
Sanewall should be largely compatible with all existing FireHOL configurations.
If you are using any variable starting "FIREHOL_" in your configuration, you will need to rename it to "SANEWALL_". See control variables: sanewall-variables(5) for a list of all variables used to control Sanewall.
In addition the default values of SANEWALL_*_ACTIVATION_POLICY, for each of INPUT, OUTPUT and FORWARD have been changed to DROP. See the entries under control variables: sanewall-variables(5) for details and how to obtain the original behaviour.
| Sanewall configuration: sanewall.conf(5) |
| control variables: sanewall-variables(5) |
| Sanewall Manual: sanewall-manual.pdf |
| Sanewall Online Documentation |
sanewall.conf — Sanewall configuration file
/etc/sanewall/sanewall.conf is the default
configuration file for Sanewall program: sanewall(1). It defines the
stateful firewall that will be produced.
A configuration file starts with an optional version indicator which looks like this:
version 5
See version config helper: sanewall-version(5) for full details.
A configuration file contains one or more interface definitions, which look like this:
interface eth0 lan
client all accept # This host can access any remote service
server ssh accept # Remote hosts can access SSH on local server
# ...
The above definition has name "lan" and specifies a network interface (eth0). A definition may contain zero or more subcommands. See interface definition: sanewall-interface(5) for full details.
A configuration file contains one or more router definitions, which look like this:
DMZ_IF=eth0
WAN_IF=eth1
router wan2dmz inface ${WAN_IF} outface ${DMZ_IF}
route http accept # Hosts on WAN may access HTTP on hosts in DMZ
server ssh accept # Hosts on WAN may access SSH on hosts in DMZ
client pop3 accept # Hosts in DMZ may access POP3 on hosts on WAN
# ...
The above definition has name "wan2dmz" and specifies incoming and outgoing network interfaces (eth1 and eth0) using variables. A definition may contain zero or more subcommands. Note that a router is not required to specify network interfaces to operate on. See router definition: sanewall-router(5) for full details.
It is simple to add extra service definitions which can then be used in the same way as those provided as standard. See the section called “Adding Services”.
The configuration file is parsed as a bash(1) script, allowing you to set up and use variables, flow control and external commands.
Special control variables: sanewall-variables(5) may be set up and used outside of any definition as can the functions in the section called “Configuration Helper Commands” and the section called “Helper Commands”.
The following variables are made available in the Sanewall configuration file and can be accessed as ${VARIABLE}.
UNROUTABLE_IPS
This variable includes the IPs from both PRIVATE_IPS
and RESERVED_IPS. It is useful to restrict
traffic on interfaces and routers accepting Internet traffic,
for example:
interface eth0 internet src not "${UNROUTABLE_IPS}"
PRIVATE_IPSThis variable includes all the IP addresses defined as Private or Test by RFC 3330.
You can override the default values by creating a file called
/etc/sanewall/PRIVATE_IPS.
RESERVED_IPSThis variable includes all the IP addresses defined by IANA as reserved.
You can override the default values by creating a file called
/etc/sanewall/RESERVED_IPS.
Now that IPv4 address space has all been allocated there is very little reason that this value will need to change in future.
MULTICAST_IPSThis variable includes all the IP addresses defined as Multicast by RFC 3330.
You can override the default values by creating a file called
/etc/sanewall/MULTICAST_IPS.
To define new services you add the appropriate lines before using them later in the configuration file.
The following are required:
server_myservice_ports="proto/sports" client_myservice_ports="cports"
proto is anything
iptables(8) accepts e.g. "tcp", "udp", "icmp",
including numeric protocol values.
sports is the ports the server is listening at.
It is a space-separated list of port numbers, names and ranges (from:to).
The keyword any will match any server port.
cports is the ports the client may use to
initiate a connection.
It is a space-separated list of port numbers, names and ranges (from:to).
The keyword any will match any client port.
The keyword default will match default client ports.
For the local machine (e.g. a client within an
interface) it resolves to sysctl
variable net.ipv4.ip_local_port_range (or
/proc/sys/net/ipv4/ip_local_port_range). For
a remote machine (e.g. a client within an
interface or anything in a router)
it resolves to the variable DEFAULT_CLIENT_PORTS (see
control variables: sanewall-variables(5)).
The following are optional:
require_myservice_modules="modules" require_myservice_nat_modules="nat-modules"
The named kernel modules will be loaded when the definition is used.
The NAT modules will only be loaded if SANEWALL_NAT is
non-zero (see control variables: sanewall-variables(5)).
For example, for a service named daftnet that listens
at two ports, port 1234 TCP and 1234 UDP where the expected client
ports are the default random ports a system may choose, plus the same
port numbers the server listens at, with further dynamic ports requiring
kernel modules to be loaded:
version 5
server_daftnet_ports="tcp/1234 udp/1234"
client_daftnet_ports="default 1234"
require_daftnet_modules="ip_conntrack_daftnet"
require_daftnet_nat_modules="ip_nat_daftnet"
interface eth0 lan0
server daftnet accept
interface eth1 lan1
client daftnet reject
router lan2lan inface eth0 outface eth1
route daftnet accept
Where multiple ports are provides (as per the example), Sanewall simply determines all of the combinations of client and server ports and generates multiple iptables statements to match them.
To create more complex rules, or stateless rules,
you will need to create a bash function prefixed rules_
e.g. rules_myservice. The best reference
is the many such functions in the main sanewall
executable.
When adding a service which uses modules, or via a custom function, you may also wish to include the following:
ALL_SHOULD_ALSO_RUN="${ALL_SHOULD_ALSO_RUN} myservice"
which will ensure your service is set-up correctly as part of the all service.
To allow definitions to be shared you can instead create files and
install them in the /etc/sanewall/services
directory with a .conf extension.
The first line must read:
FHVER 1:213
1 is the service definition API version. It will be changed if the API is ever modified. 213 refers to a FireHOL version and is retained for compatibility.
Sanewall will refuse to run if the API version does not match the expected one. The minor number is ignored.
At version 1:213, the API and therefore service definitions are compatible with FireHOL.
| policy command: sanewall-policy(5) |
| protection command: sanewall-protection(5) |
| server, route commands: sanewall-server(5) |
| client command: sanewall-client(5) |
| group command: sanewall-group(5) |
These helpers can be used in interface and router definitions as well as before them.
| iptables helper: sanewall-iptables(5) |
| masquerade helper: sanewall-masquerade(5) |
This helper can be used in router definitions as well as before any router or interface.
| tcpmss helper: sanewall-tcpmss(5) |
These helpers should only be used outside of interface and router definitions (i.e. before the first interface is defined).
sanewall-variables — Variables controlling Sanewall
There are a number of variables that control the behaviour of Sanewall.
All variables may be set in the main Sanewall
configuration file /etc/sanewall/sanewall.conf.
Variables which affect the runtime but not the created firewall may also be set as environment variables before running sanewall. These can change the default values but will be overwritten by values set in the configuration file. If a variable can be set by an environment variable it is specified below.
Sanewall also sets some variables before processing the configuration file which you can use as part of your configuration. These are described in Sanewall configuration: sanewall.conf(5).
DEFAULT_INTERFACE_POLICYThis variable controls the default action to be taken on traffic not matched by any rule within an interface. It can be overridden using policy command: sanewall-policy(5).
Packets that reach the end of an interface without an
action of return or accept are logged. You can control the
frequency of this logging by altering
SANEWALL_LOG_FREQUENCY.
Default:
DEFAULT_INTERFACE_POLICY="DROP"
Example:
DEFAULT_INTERFACE_POLICY="REJECT"
DEFAULT_ROUTER_POLICYThis variable controls the default action to be taken on traffic not matched by any rule within a router. It can be overridden using policy command: sanewall-policy(5).
Packets that reach the end of a router without an
action of return or accept are logged. You can control the
frequency of this logging by altering
SANEWALL_LOG_FREQUENCY.
Default:
DEFAULT_ROUTER_POLICY="RETURN"
Example:
DEFAULT_ROUTER_POLICY="REJECT"
UNMATCHED_INPUT_POLICY, UNMATCHED_OUTPUT_POLICY, UNMATCHED_FORWARD_POLICYThese variables control the default action to be taken on traffic not matched by any interface or router definition that was incoming, outgoing or for forwarding respectively. Any supported value from actions for rules: sanewall-actions(5) may be set.
All packets that reach the end of a chain are logged, regardless
of these settings. You can control the frequency of this logging
by altering SANEWALL_LOG_FREQUENCY.
Defaults:
UNMATCHED_INPUT_POLICY="DROP"
UNMATCHED_OUTPUT_POLICY="DROP"
UNMATCHED_FORWARD_POLICY="DROP"
Example:
UNMATCHED_INPUT_POLICY="REJECT"
UNMATCHED_OUTPUT_POLICY="REJECT"
UNMATCHED_FORWARD_POLICY="REJECT"
SANEWALL_INPUT_ACTIVATION_POLICY, SANEWALL_OUTPUT_ACTIVATION_POLICY, SANEWALL_FORWARD_ACTIVATION_POLICY, SANEWALL_ESTABLISHED_ACTIVATION_ACCEPT
These variables control the default action to be taken on
traffic during firewall activation for incoming, outgoing and
forwarding respectively. Acceptable values are
ACCEPT, DROP
and REJECT. They may be set as environment
variables.
During activation, Sanewall creates
temporary rules to ALLOW already established traffic
(new connections honour the appropriate variable). Set
SANEWALL_ESTABLISHED_ACTIVATION_ACCEPT to 0 to
prevent this.
Unlike FireHOL which defaults all values to
ACCEPT, Sanewall defaults
all values to DROP.
If you wish to reinstate the old FireHOL
behaviour, set these values to ACCEPT. Please do
not do so if you are using all or
any to match traffic; connections established
during activation will continue even if they would not be allowed
once the firewall is established.
Defaults:
SANEWALL_INPUT_ACTIVATION_POLICY="DROP"
SANEWALL_OUTPUT_ACTIVATION_POLICY="DROP"
SANEWALL_FORWARD_ACTIVATION_POLICY="DROP"
SANEWALL_ESTABLISHED_ACTIVATION_ACCEPT="1"
Example:
UNMATCHED_INPUT_POLICY="ACCEPT"
UNMATCHED_OUTPUT_POLICY="ACCEPT"
UNMATCHED_FORWARD_POLICY="ACCEPT"
SANEWALL_ESTABLISHED_ACTIVATION_ACCEPT="0"
SANEWALL_LOG_MODEThis variable controls method that Sanewall uses for logging.
Acceptable values are LOG (normal syslog) and
ULOG (netfilter ulogd).
When ULOG is selected,
SANEWALL_LOG_LEVEL is ignored.
Default:
SANEWALL_LOG_MODE="LOG"
Example:
SANEWALL_LOG_MODE="ULOG"
To see the available options run:
/sbin/iptables -j LOG --help
or
/sbin/iptables -j ULOG --help
SANEWALL_LOG_LEVELThis variable controls the level at which events will be logged to syslog.
To avoid packet logs appearing on your console you should ensure klogd only logs traffic that is more important than that produced by Sanewall.
Use the following option to choose an iptables log level
(alpha or numeric) which is higher than the -c
of klogd.
Table 1. iptables/klogd levels
| iptables | klogd | description |
|---|---|---|
| emerg (0) | 0 | system is unusable |
| alert (1) | 1 | action must be taken immediately |
| crit (2) | 2 | critical conditions |
| error (3) | 3 | error conditions |
| warning (4) | 4 | warning conditions |
| notice (5) | 5 | normal but significant condition |
| info (6) | 6 | informational |
| debug (7) | 7 | debug-level messages |
The default for klogd is generally to log everything (7 and lower) and the default level for iptables is to log as warnings (4).
SANEWALL_LOG_OPTIONSThis variable controls the way in which events will be logged to syslog.
Default:
SANEWALL_LOG_OPTIONS="--log-level warning"
Example:
SANEWALL_LOG_OPTIONS="--log-level info \
--log-tcp-options --log-ip-options"
To see the available options run:
/sbin/iptables -j LOG --help
SANEWALL_LOG_FREQUENCY, SANEWALL_LOG_BURST
These variables control the frequency that each logging rule will
write events to syslog. SANEWALL_LOG_FREQUENCY
is set to the maximum average frequency and
SANEWALL_LOG_BURST specifies the maximum initial
number.
Default:
SANEWALL_LOG_FREQUENCY="1/second"
SANEWALL_LOG_BURST="5"
Example:
SANEWALL_LOG_FREQUENCY="30/minute"
SANEWALL_LOG_BURST="2"
To see the available options run:
/sbin/iptables -m limit --help
SANEWALL_LOG_PREFIXThis value is added to the contents of each logged line for easy detection of Sanewall lines in the system logs. By default it is empty.
Default:
SANEWALL_LOG_PREFIX=""
Example:
SANEWALL_LOG_PREFIX="SANEWALL:"
SANEWALL_DROP_INVALID
If set to 1, this variable causes Sanewall
to drop all packets matched as INVALID
in the iptables(8) connection tracker.
You can use protection command: sanewall-protection(5) to control matching
of INVALID packets and others on per-interface
and per-router basis.
Default:
SANEWALL_DROP_INVALID="0"
Example:
SANEWALL_DROP_INVALID="1"
DEFAULT_CLIENT_PORTSThis variable controls the port range that is used when a remote client is specified. For clients on the local host, Sanewall finds the exact client ports by querying the kernel options.
Default:
DEFAULT_CLIENT_PORTS="1000:65535"
Example:
DEFAULT_CLIENT_PORTS="0:65535"
SANEWALL_NATIf set to 1, this variable causes Sanewall to load the NAT kernel modules. If you make use of the NAT helper commands, the variable will be set to 1 automatically. It may be set as an environment variable.
Default:
SANEWALL_NAT="0"
Example:
SANEWALL_NAT="1"
SANEWALL_ROUTINGIf set to 1, this variable causes Sanewall to enable routing in the kernel. If you make use of router definitions or certain helper commands the variable will be set to 1 automatically. It may be set as an environment variable.
Default:
SANEWALL_ROUTING="0"
Example:
SANEWALL_ROUTING="1"
SANEWALL_AUTOSAVE
This variable specifies the file of (IPv4) rules that will be
created when Sanewall program: sanewall(1) is called with
the save argument. It may be set as an
environment variable.
If the variable is not set, a system-specific value is used which was defined at configure-time. If no value was chosen then the save fails.
Default:
SANEWALL_AUTOSAVE=""
Example:
SANEWALL_AUTOSAVE="/tmp/sanewall-saved-ipv4.txt"
SANEWALL_AUTOSAVE6
This variable specifies the file of (IPv6) rules that will be
created when Sanewall program: sanewall(1) is called with
the save argument. It may be set as an
environment variable.
If the variable is not set, a system-specific value is used which was defined at configure-time. If no value was chosen then the save fails.
Default:
SANEWALL_AUTOSAVE6=""
Example:
SANEWALL_AUTOSAVE6="/tmp/sanewall-saved-ipv6.txt"
SANEWALL_LOAD_KERNEL_MODULESIf set to 0, this variable forces Sanewall to not load any kernel modules. It is needed only if the kernel has modules statically included and in the rare event that Sanewall cannot access the kernel configuration. It may be set as an environment variable.
Default:
SANEWALL_LOAD_KERNEL_MODULES="1"
Example:
SANEWALL_LOAD_KERNEL_MODULES="0"
SANEWALL_TRUST_LOOPBACKIf set to 0, the loopback device "lo" will not be trusted and you can write standard firewall rules for it.
If you do not set up appropriate rules, local processes will not be able to communicate with each other which can result in serious breakages.
By default "lo" is trusted and all INPUT and
OUTPUT traffic is accepted (forwarding is
not included).
Default:
SANEWALL_TRUST_LOOPBACK="1"
Example:
SANEWALL_TRUST_LOOPBACK="0"
SANEWALL_DROP_ORPHAN_TCP_ACK_FINIf set to 1, Sanewall will drop all TCP connections with ACK FIN set without logging them.
In busy environments the iptables connection tracker removes connection tracking list entries as soon as it receives a FIN. This makes the ACK FIN appear as an invalid packet which will normally be logged by Sanewall.
Default:
SANEWALL_DROP_ORPHAN_TCP_ACK_FIN="0"
Example:
SANEWALL_DROP_ORPHAN_TCP_ACK_FIN="1"
SANEWALL_DEBUGGINGIf set to a non-empty value, switches on debug output so that it is possible to see what processing Sanewall is doing.
This variable can only be set as an environment variable, since it is processed before any configuration files are read.
Default:
SANEWALL_DEBUGGING=""
Example:
SANEWALL_DEBUGGING="Y"
WAIT_FOR_IFACEIf set to the name of a network device (e.g. eth0), Sanewall will wait until the device is up (or until 60 seconds have elapsed) before continuing.
This variable can only be set as an environment variable, since it determines when the main configuration file will be processed.
A device does not need to be up in order to have firewall rules created for it, so this option should only be used if you have a specific need to wait (e.g. the network must be queried to determine the hosts or ports which will be firewalled).
Default:
WAIT_FOR_IFACE=""
Example:
WAIT_FOR_IFACE="eth0"
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| nat, snat, dnat, redirect config helpers: sanewall-nat(5) |
| administration tool for IPv4 firewalls: iptables(8) |
sanewall-interface — create an interface definition
interface real-interface name [rule-params]
An interface definition creates a firewall for protecting the host on which the firewall is running.
The default policy is DROP, so that if no subcommands are given, the firewall will just drop all incoming and outgoing traffic using this interface.
The behaviour of the defined interface is controlled by adding subcommands (listed in the section called “See Also”).
Forwarded traffic is never matched by the interface rules, even if it was originally destined for the firewall but was redirected using NAT. Any traffic to be passed through the firewall for whatever reason must be in a router (see router definition: sanewall-router(5)).
real-interface
This is the interface name as shown by
ip link show.
Generally anything iptables accepts
is valid.
The + (plus sign) after some text will match all interfaces that start with this text.
Multiple interfaces may be specified by enclosing them within quotes, delimited by spaces for example:
interface "eth0 eth1 ppp0" myname
nameThis is a name for this interface. You should use short names (10 characters maximum) without spaces or other symbols.
A name should be unique for all Sanewall interface and router definitions.
rule-paramsThe set of rule parameters to further restrict the traffic that is matched to this interface.
See optional rule parameters: sanewall-rule-params(5) for information on the parameters that can be used. Some examples:
interface eth0 intranet src 192.0.2.0/24
interface eth0 internet src not "${UNROUTABLE_IPS}"
See Sanewall configuration: sanewall.conf(5) for an explanation
of ${UNROUTABLE_IPS}.
sanewall-router — create a router definition
router name [rule-params]
A router definition consists of a set of rules for traffic passing through the host running the firewall.
The default policy for router definitions is RETURN, meaning packets are not dropped by any particular router. Packets not matched by any router are dropped at the end of the firewall.
The behaviour of the defined router is controlled by adding subcommands (listed in the section called “See Also”).
nameThis is a name for this router. You should use short names (10 characters maximum) without spaces or other symbols.
A name should be unique for all Sanewall interface and router definitions.
rule-paramsThe set of rule parameters to further restrict the traffic that is matched to this router.
See optional rule parameters: sanewall-rule-params(5) for information on the parameters that can be used. Some examples:
router mylan inface ppp+ outface eth0 src not ${UNROUTABLE_IPS}
router myrouter
See Sanewall configuration: sanewall.conf(5) for an explanation
of ${UNROUTABLE_IPS}.
Routers create stateful iptables rules which match traffic in both directions.
To match some client or server traffic, the input/output interface
or source/destination of the request must be specified. All
inface/outface and
src/dst
optional rule parameters: sanewall-rule-params(5) can be given on the router statement
(in which case they will be applied to all subcommands for the router)
or just within the subcommands of the router.
For example, to define a router which matches requests from any PPP interface and destined for eth0, and on this allowing HTTP servers (on eth0) to be accessed by clients (from PPP) and SMTP clients (from eth0) to access any servers (on PPP):
router mylan inface ppp+ outface eth0
server http accept
client smtp accept
The client subcommand reverses any optional
rule parameters passed to the router, in this
case the inface and outface.
Equivalently, to define a router which matches all forwarded traffic and within the the router allow HTTP servers on eth0 to be accessible to PPP and any SMTP servers on PPP to be accessible from eth0:
router mylan
server http accept inface ppp+ outface eth0
server smtp accept inface eth0 outface ppp
In this instance two server subcommands are used
since there are no parameters on the router to reverse. Avoid the
use of the client subcommand in routers unless
the inputs and outputs are defined as part of the router.
Any number of routers can be defined and the traffic they match can overlap. Since the default policy is RETURN, any traffic that is not matched by any rules in one will proceed to the next, in order, until none are left.
sanewall-policy — set default action for a definition
policy action
The policy subcommand defines the default policy for an interface or router.
The action can be any of the actions listed in
actions for rules: sanewall-actions(5).
Change the default policy of a router only if you understand clearly what will be matched by the router statement whose policy is being changed.
It is common to define overlapping router definitions. Changing the
policy to anything other than the default return
may cause strange results for your configuration.
Do not set a policy to accept unless you fully
trust all hosts that can reach the interface.
Sanewall CANNOT create valid "accept by
default" firewalls. See this
FireHOL bug report for
some more information and history.
sanewall-protection — add extra protections to a definition
protection [reverse] flood-protection-type [requests/period
[burst]
]
protection [reverse] strong [requests/period
[burst]
]
protection [reverse]
{ bad-packets |
packet-protection-type
}
The protection subcommand sets protection rules on an interface or router.
Flood protections honour the options requests/period
and burst. They are used to limit the rate of certain
types of traffic.
The default rate Sanewall uses is 100
operations per second with a burst of 50.
Run iptables -m limit --help for more information.
The protection type strong will switch on
all protections (both packet and flood protections) except
all-floods. It has aliases
full and all.
The protection type bad-packets will switch on
all packet protections but not flood protections.
You can specify multiple protection types by using multiple protection commands or in a single command by enclosing the types in quotes.
On a router, protections are normally set up
on inface.
The reverse option will set up the protections
on outface. You must use it as the
first keyword.
Drops all incoming invalid packets, as detected INVALID by the connection tracker.
See also SANEWALL_DROP_INVALID in
control variables: sanewall-variables(5) which allows setting
this function globally.
Drops all packet fragments.
This rule will probably never match anything since iptables(8) reconstructs all packets automatically before the firewall rules are processed whenever connection tracking is running.
Drops all TCP packets that initiate a socket but have not got the SYN flag set.
Drops all TCP packets that have all TCP flags set.
Drops all TCP packets that have all TCP flags unset.
Drops all TCP packets that have illegal combinations of TCP flags set.
Allows only a certain amount of ICMP echo requests.
Allows only a certain amount of new TCP connections.
Be careful to not set the rate too low as the rule is applied to all connections regardless of their final result (rejected, dropped, established, etc).
Allows only a certain amount of new connections.
Be careful to not set the rate too low as the rule is applied to all connections regardless of their final result (rejected, dropped, established, etc).
When using multiple types in a single command, if the quotes are forgotten, incorrect rules will be generated without warning.
When using multiple types in a single command,
Sanewall will silently ignore any types that
come after a group type (bad-packets,
strong and its aliases). Only use group types on
their own line.
sanewall-server — accept requests to a service
server service action [rule-params]
route service action [rule-params]
The server subcommand defines a server of a service
on an interface or router.
Any rule-params given to a parent interface or
router are inherited by the server.
For Sanewall a server is the destination of a request. Even though this is more complex for some multi-socket services, to Sanewall a server always accepts requests.
The route subcommand is an alias for server which may only be used in routers.
The service parameter is one of the
supported service names from services list: sanewall-services(5). Multiple
services may be specified, space delimited in quotes.
The action can be any of the actions listed in
actions for rules: sanewall-actions(5).
The rule-params
sanewall-client — accept replies from a service
client service action [rule-params]
The client subcommand defines a client of a service
on an interface or router.
Any rule-params given to a parent interface or
router are inherited by the client, but are reversed.
For Sanewall a client is the source of a request. Even though this is more complex for some multi-socket services, to Sanewall a client always initiates the connection.
The service parameter is one of the
supported service names from services list: sanewall-services(5). Multiple
services may be specified, space delimited in quotes.
The action can be any of the actions listed in
actions for rules: sanewall-actions(5).
The rule-params
sanewall-group — group commands with common options
group with [rule-params]
group end
The group command allows you to group together multiple client and server commands.
Grouping commands with common options (see optional rule parameters: sanewall-rule-params(5)) allows the option values to be checked only once in the generated firewall rather than once per service, making it more efficient.
Nested groups may be used.
This:
interface any world
client all accept
server http accept
# Provide these services to trusted hosts only
server "ssh telnet" accept src "192.0.2.1 192.0.2.2"
can be replaced to produce a more efficient firewall by this:
interface any world
client all accept
server http accept
# Provide these services to trusted hosts only
group with src "192.0.2.1 192.0.2.2"
server ssh telnet
server ssh accept
group end
sanewall-version — set version number of configuration file
version 5
The version helper command states the configuration file version.
If the value passed is newer than the running version of Sanewall supports, Sanewall will not run.
You do not have to specify a version number for a configuration file, but by doing so you will prevent Sanewall trying to process a file which it cannot handle.
The value that Sanewall expects is increased every time that the configuration file format changes.
sanewall-action — set up custom filter actions
action chain name action
The action helper command creates an iptables chain which can be used to control the action of other firewall rules once the firewall is running.
For example, you can setup the custom action ACT1, which by default is ACCEPT, but can be dynamically changed to DROP, REJECT or RETURN (and back) without restarting the firewall.
The name
The name
The action
To create a custom chain and have some rules use it:
action chain ACT1 accept
interface any world
server smtp ACT1
client smtp ACT1
Once the firewall is running you can dynamically modify the behaviour of the chain from the Linux command-line, as detailed below:
To insert a DROP action at the start of the chain to override the default action (ACCEPT):
iptables -t filter -I ACT1 -j DROP
To delete the DROP action from the start of the chain to return to the default action:
iptables -t filter -D ACT1 -j DROP
If you delete all of the rules in the chain, the default will be to RETURN, in which case the behaviour will be as if any rules with the action were not present in the configuration file.
You can also create multiple chains simultaneously. To create 3 ACCEPT and 3 DROP chains you can do the following:
action chain "ACT1 ACT2 ACT3" accept
action chain "ACT4 ACT5 ACT6" drop
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| actions for rules: sanewall-actions(5) |
| administration tool for IPv4 firewalls: iptables(8) |
sanewall-blacklist — set up a unidirectional or bidirectional blacklist
blacklist [ full | all ] ip...
blacklist { input | them | him | her | it | this | these } ip...
The blacklist helper command creates a blacklist
for the ip
If the type full or one of its aliases is supplied,
or no type is given, a bidirectional stateless blacklist will be generated.
The firewall will REJECT all traffic going to the IP addresses and
DROP all traffic coming from them.
If the type input or one of its aliases is supplied,
a unidirectional stateful blacklist will be generated. Connections
can be initiated to such IP addresses, but the IP addresses will not
be able to connect to the firewall or hosts protected by it.
Any blacklists will affect all router and interface definitions. They must be declared before the first router or interface.
sanewall-classify — classify traffic for traffic shapping tools
classify class [rule-params]
The classify helper command puts matching traffic into the specified traffic shaping class.
The class is a class as used by
iptables and tc (e.g. MAJOR:MINOR).
The rule-params
Any classify commands will affect all traffic matched. They must be declared before the first router or interface.
# Put all smtp traffic leaving via eth1 in class 1:1
classify 1:1 outface eth1 proto tcp dport 25
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| administration tool for IPv4 firewalls: iptables(8) |
| show / manipulate traffic control settings: tc(8) |
| Linux Advanced Routing & Traffic Control HOWTO |
sanewall-connmark — set a stateful mark on a connection
connmark { value | save | restore } chain [rule-params]
The connmark helper command sets a mark on a whole connection. It applies to both directions.
To set a mark on packets matching particular rules, regardless of any connection, see mark config helper: sanewall-mark(5).
The value is the mark value to set (a 32 bit
integer). If you specify save then the mark on the
matched packet will be turned into a connmark. If you specify
restore then the matched packet will have its mark
set to the current connmark.
The chain will be used to find traffic to
mark. It can be any of the iptables built in chains
belonging to the mangle table. The chain names
are: INPUT, FORWARD, OUTPUT, PREROUTING and POSTROUTING. The names are
case-sensitive.
The rule-params
Any connmark commands will affect all traffic matched. They must be declared before the first router or interface.
Consider a scenario with 3 ethernet ports, where eth0 is on the local LAN, eth1 connects to ISP 'A' and eth2 to ISP 'B'. To ensure traffic leaves via the same ISP as it arrives from you can mark the traffic:
# mark connections when they arrive from the ISPs
connmark 1 PREROUTING inface eth1
connmark 2 PREROUTING inface eth2
# restore the mark (from the connmark) when packets arrive from the LAN
connmark restore OUTPUT
connmark restore PREROUTING inface eth0
It is then possible to use the commands from iproute2 such as ip, to pick the correct routing table based on the mark on the packets.
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| mark config helper: sanewall-mark(5) |
| administration tool for IPv4 firewalls: iptables(8) |
| show / manipulate routing, devices, policy routing and tunnels: ip(8) |
| Linux Advanced Routing & Traffic Control HOWTO |
sanewall-dscp — set the DSCP field in the packet header
dscp { value | class classid } chain [rule-params]
The dscp helper command sets the DSCP field in the header of packets traffic, to allow QoS shaping.
There is also a dscp parameter which allows matching DSCP values within individual rules (see optional rule parameters: sanewall-rule-params(5)).
Set value to a decimal or hexadecimal
(0xnn) number to set an explicit DSCP value or use class
classid to use an iptables DiffServ class,
such as EF, BE, CSxx or AFxx
(see iptables -j DSCP --help for more information).
The chain will be used to find traffic to
mark. It can be any of the iptables built in chains
belonging to the mangle table. The chain names
are: INPUT, FORWARD, OUTPUT, PREROUTING and POSTROUTING. The names are
case-sensitive.
The rule-params
Any dscp commands will affect all traffic matched. They must be declared before the first router or interface.
# set DSCP field to 32, packets sent by the local machine
dscp 32 OUTPUT
# set DSCP field to 32 (hex 20), packets routed by the local machine
dscp 0x20 FORWARD
# set DSCP to DiffServ class EF, packets routed by the local machine
# and destined for port TCP/25 of 198.51.100.1
dscp class EF FORWARD proto tcp dport 25 dst 198.51.100.1
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| administration tool for IPv4 firewalls: iptables(8) |
| show / manipulate routing, devices, policy routing and tunnels: ip(8) |
| Linux Advanced Routing & Traffic Control HOWTO |
| optional rule parameters: sanewall-rule-params(5) |
sanewall-mac — ensure source IP and source MAC address match
mac IP macaddr
Any mac commands will affect all traffic destined for the firewall host, or to be forwarded by the host. They must be declared before the first router or interface.
There is also a mac parameter which allows matching MAC addresses within individual rules (see optional rule parameters: sanewall-rule-params(5)).
The mac helper command DROPs traffic from
any IP address that was not sent
using the macaddr specified.
When packets are dropped, a log is produced with the label "MAC MISSMATCH" (sic.). mac obeys the default log limits (see the section called “Logging” in optional rule parameters: sanewall-rule-params(5)).
This command restricts an IP to a particular MAC address. The same MAC address is permitted send traffic with a different IP.
sanewall-mark — mark traffic for traffic shaping tools
mark value chain [rule-params]
The mark helper command sets a mark on packets that can be matched by traffic shaping tools for controlling the traffic.
To set a mark on whole connections, see connmark config helper: sanewall-connmark(5). There is also a mark parameter which allows matching marks within individual rules (see optional rule parameters: sanewall-rule-params(5)).
The value is the mark value to set (a 32 bit
integer).
The chain will be used to find traffic to
mark. It can be any of the iptables built in chains
belonging to the mangle table. The chain names
are: INPUT, FORWARD, OUTPUT, PREROUTING and POSTROUTING. The names are
case-sensitive.
The rule-params
Any mark commands will affect all traffic matched. They must be declared before the first router or interface.
If you want to do policy based routing based on iptables marks, you will need to disable the Root Path Filtering on the interfaces involved (rp_filter in sysctl).
# mark with 1, packets sent by the local machine
mark 1 OUTPUT
# mark with 2, packets routed by the local machine
mark 2 FORWARD
# mark with 3, packets routed by the local machine, sent from
# 192.0.2.2 destined for port TCP/25 of 198.51.100.1
mark 3 FORWARD proto tcp dport 25 dst 198.51.100.1 src 192.0.2.2
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| connmark config helper: sanewall-connmark(5) |
| administration tool for IPv4 firewalls: iptables(8) |
| show / manipulate routing, devices, policy routing and tunnels: ip(8) |
| Linux Advanced Routing & Traffic Control HOWTO |
| optional rule parameters: sanewall-rule-params(5) |
sanewall-nat — set up NAT and port redirections
snat [to] target [rule-params]
dnat [to] target [rule-params]
redirect [to] portrange [rule-params]
nat { to-source | to-destination | redirect-to } target [rule-params]
nat redirect-to portrange [rule-params]
The rule-params
The snat helper sets up a Source NAT rule for routed traffic by calling nat to-source. For example:
snat to 192.0.2.1 outface eth0 src 198.51.100.1 dst 203.0.113.1
The dnat helper sets up a Destination NAT rule for routed traffic by calling nat to-destination. For example:
dnat to 192.0.2.1 outface eth0 src 198.51.100.1 dst 203.0.113.1
The redirect helper redirects matching traffic
to portrange on the local host
by calling nat redirect-to. For
example:
redirect-to 8080 inface eth0 src 198.51.100.0/24 proto tcp dport 80
The nat helper takes one of the following sub-commands:
targetDefines a Source NAT (created in table NAT, chain POSTROUTING).
target is the source address to be
set in packets matching
rule-params
If no rules are given, all forwarded traffic will be matched.
inface should not be used in SNAT since the
information is not available at the time the decision is made.
target accepts any
--to-source values that
iptables(8) accepts. Run
iptables -j SNAT --help to for more
information. Multiple targets may
be specified by separating with spaces and enclosing with
quotes.
targetDefines a Destination NAT (created in table NAT, chain POSTROUTING).
target is the destination address to be
set in packets matching
rule-params
If no rules are given, all forwarded traffic will be matched.
outface should not be used in DNAT since the
information is not available at the time the decision is made.
target accepts any
--to-destination values that
iptables(8) accepts. Run
iptables -j DNAT --help to for more
information. Multiple targets may
be specified by separating with spaces and enclosing with
quotes.
portrangeRedirect matching traffic to the local machine (created in table NAT, chain PREROUTING).
portrange is the port range
(from-to) or single port that packets matching
rule-params
If no rules are given, all forwarded traffic will be matched.
outface should not be used in REDIRECT since the
information is not available at the time the decision is made.
# Send to 192.0.2.1 # - all traffic arriving at or passing through the firewall nat to-destination 192.0.2.1 # Send to 192.0.2.1 # - all traffic arriving at or passing through the firewall # - which WAS going to 203.0.113.1 nat to-destination 192.0.2.1 dst 203.0.113.1 # Send to 192.0.2.1 # - TCP traffic arriving at or passing through the firewall # - which WAS going to 203.0.113.1 nat to-destination 192.0.2.1 proto tcp dst 203.0.113.1 # Send to 192.0.2.1 # - TCP traffic arriving at or passing through the firewall # - which WAS going to 203.0.113.1, port 25 nat to-destination 192.0.2.1 proto tcp dport 25 dst 203.0.113.1 # Other examples nat to-source 192.0.2.1 outface eth0 src 198.51.100.1 dst 203.0.113.1 nat to-destination 192.0.2.2 outface eth0 src 198.51.100.2 dst 203.0.113.2 nat redirect-to 8080 inface eth0 src 198.51.100.0/24 proto tcp dport 80
sanewall-transparent_proxy — set up a transparent proxy
transparent_proxy service port user [rule-params]
transparent_squid port user [rule-params]
The transparent_proxy helper command sets up transparent caching for TCP traffic.
The proxy application must be running on the
firewall host at port port with the
credentials of the local user user (which
may be a space-delimited list enclosed in quotes) serving requests
appropriate to the TCP port service.
The rule-params
For traffic destined for the firewall host or passing
through the firewall, do not use the outface
rule because the rules are applied before the routing decision and
so the outgoing interface will not be known.
An empty user string ("") disables
caching of locally-generated traffic. Otherwise, traffic starting
from the firewall is captured, except traffic generated by
the local user(s) user.
The inface, outface and
src rule-params are all
ignored for locally-generated traffic.
The transparent_squid helper command sets up
the special case for HTTP traffic with service
implicitly set to 80.
transparent_proxy 80 3128 squid inface eth0 src 192.0.2.0/24 transparent_squid 3128 squid inface eth0 src 192.0.2.0/24 transparent_proxy "80 3128 8080" 3128 "squid privoxy root bin" \ inface not "ppp+ ipsec+" dst not "a.not.proxied.server" transparent_squid "80 3128 8080" "squid privoxy root bin" \ inface not "ppp+ ipsec+" dst not "non.proxied.server"
sanewall-tos — set the Type of Service (TOS) of packets
tos value chain [rule-params]
The tos helper command sets the Type of Service (TOS) field in packet headers.
There is also a tos parameter which allows matching TOS values within individual rules (see optional rule parameters: sanewall-rule-params(5)).
The value can be an integer number (decimal
or hexadecimal) or one of the descriptive values accepted by
iptables (run
iptables -j TOS --help for a list).
The chain will be used to find traffic to
mark. It can be any of the iptables built in chains
belonging to the mangle table. The chain names
are: INPUT, FORWARD, OUTPUT, PREROUTING and POSTROUTING. The names are
case-sensitive.
The rule-params
Any tos commands will affect all traffic matched. They must be declared before the first router or interface.
# set TOS to 16, packets sent by the local machine
tos 16 OUTPUT
# set TOS to 0x10 (16), packets routed by the local machine
tos 0x10 FORWARD
# set TOS to Maximize-Throughput (8), packets routed by the local
# machine, destined for port TCP/25 of 198.51.100.1
tos Maximize-Throughput FORWARD proto tcp dport 25 dst 198.51.100.1
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| tosfix config helper: sanewall-tosfix(5) |
| administration tool for IPv4 firewalls: iptables(8) |
| optional rule parameters: sanewall-rule-params(5) |
sanewall-tosfix — apply suggested TOS values to packets
tosfix
The tosfix helper command sets the Type of Service (TOS) field in packet headers based on the suggestions given by Erik Hensema in iptables and tc shapping tricks .
The following TOS values are set:
All TCP ACK packets with length less than 128 bytes are assigned Minimize-Delay, while bigger ones are assigned Maximize-Throughput
All packets with TOS Minimize-Delay, that are bigger than 512 bytes are set to Maximize-Throughput, except for short bursts of 2 packets per second
The tosfix command must be used before the first router or interface.
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| tos config helper: sanewall-tos(5) |
| administration tool for IPv4 firewalls: iptables(8) |
sanewall-iptables — include custom iptables commands
iptables argument...
The iptables helper command passes all of its arguments to the real iptables(8) at the appropriate point during run-time.
When used in an interface or router, the result will not have a direct relationship to the enclosing definition as the parameters passed are only those you supply.
You should not use /sbin/iptables directly in a Sanewall configuration as it will run before Sanewall activates its firewall. This means they it be applied to the running firewall, not the new firewall, so will be removed when the new firewall is activated.
The iptables helper is provided to allow you to hook in commands safely.
| Sanewall program: sanewall(1) |
| Sanewall configuration: sanewall.conf(5) |
| administration tool for IPv4 firewalls: iptables(8) |
sanewall-masquerade — set up masquerading (NAT) on an interface
masquerade real-interface [rule-params]
masquerade [reverse] [rule-params]
The masquerade helper command sets up masquerading on the output of a real network interface (as opposed to a Sanewall interface definition).
If a real-interface is specified the command
should be used before any interface or router definitions. Multiple
values can be given separated by whitespace, so long as they are
enclosed in quotes.
If used within an interface definition the definition's
real-interface will be used.
If used within a router definition the definition's
outface(s) will be used if specified.
If the reverse option is gived, then the definition's
inface(s) will be used if specified.
Unlike most commands, masquerade does not
inherit its parent definition's rules-params,
it only honour's its own. The inface and
outface parameters should not be used
(iptables does not support inface in the POSTROUTING chain and outface
will be overwritten by Sanewall using the
rules above).
The masquerade always applies to the output of the chosen network interfaces.
SANEWALL_NAT will be turned on automatically
(see control variables: sanewall-variables(5)) and
Sanewall will enable packet-forwarding
in the kernel.
Masquerading is a special form of Source NAT (SNAT) that changes the source of requests when they go out and replaces their original source when they come in. This way a Linux host can become an Internet router for a LAN of clients having unroutable IP addresses. Masquerading takes care to re-map IP addresses and ports as required.
Masquerading is expensive compare to SNAT because it checks the IP address of the outgoing interface every time for every packet. If your host has a static IP address you should generally prefer SNAT.
# Before any interface or router masquerade eth0 src 192.0.2.0/24 dst not 192.0.2.0/24 # In an interface definition to masquerade the output of its real-interface masquerade # In a router definition to masquerade the output of its outface masquerade # In a router definition to masquerade the output of its inface masquerade reverse
sanewall-tcpmss — set the MSS of TCP SYN packets for routers
tcpmss { mss | auto }
The tcpmss helper command sets the MSS (Maximum Segment Size) of TCP SYN packets routed through the firewall. This can be used to overcome situations where Path MTU Discovery is not working and packet fragmentation is not possible.
A numeric mss will set MSS of TCP
connections to the value given. Using the word auto
will set the MSS to the MTU of the outgoing interface minus 40
(clamp-mss-to-pmtu).
If used within a router definition the MSS will be applied on the
outface(s) of the router. If used before
any router or interface definitions it will be applied to all traffic
passing through the firewall.
The tcpmss command cannot be used in an interface.
sanewall-rule-params — optional rule parameters
Common
src [not] host
dst [not] host
srctype [not] type
dsttype [not] type
proto [not] protocol
mac [not] macaddr
dscp [not] { value | class classid }
mark [not] id
tos [not] id
custom "iptables-options..."
Router Only
inface [not] interface
outface [not] interface
physin [not] interface
physout [not] interface
Interface Only
uid [not] user
gid [not] group
Logging
log "log text" [level loglevel]
loglimit "log text" [level loglevel]
Optional rule parameters are accepted by many commands to narrow the match they make. Not all parameters are accepted by all commands so you should check the individual commands for exclusions.
All matches are made against the REQUEST. Sanewall automatically sets up the necessary stateful rules to deal with replies in the reverse direction.
Use the option not to match any value other than the
one(s) specified.
The logging parameters are unusual in that they do not affect the
match, they just cause a log message to be emitted. Therefore, the
logging parameters don't support the not option.
Sanewall is designed so that if you specify a parameter that is also used internally by the command then a warning will be issued (and the internal version will be used).
Use src and dst to define the
source and destination IP addresses of the request respectively.
host defines the IP or IPs to be matched.
Examples:
server smtp accept src not 192.0.2.1
server smtp accept dst 198.51.100.1
server smtp accept src not 192.0.2.1 dst 198.51.100.1
Use srctype or dsttype to define
the source or destination IP address type of the request.
type is the address type category as used
in the kernel's network stack. It can be one of:
an unspecified address (i.e. 0.0.0.0)
a unicast address
a local address
a broadcast address
an anycast address
a multicast address
a blackhole address
an unreachable address
a prohibited address
undocumented
See iptables(8) or run
iptables -m addrtype --help for more information.
Examples:
server smtp accept srctype not "UNREACHABLE PROHIBIT"
Use proto to match by protocol. The
protocol can be any accepted by iptables(8).
Use mac to match by MAC address. The
macaddr matches to the "remote" host.
In an interface, "remote" always means the non-local
host.
In a router, "remote" refers to the source of
requests for servers. It refers to the destination
of requests for clients.
Examples:
# Only allow pop3 requests to the e6 host
client pop3 accept mac 00:01:01:00:00:e6
# Only allow hosts other than e7/e8 to access smtp
server smtp accept mac not "00:01:01:00:00:e7 00:01:01:00:00:e8"
Use dscp to match the DSCP field on packets. For details
on DSCP values and
classids, see dscp config helper: sanewall-dscp(5).
server smtp accept dscp not "0x20 0x30"
server smtp accept dscp not class "BE EF"
Use mark to match marks set on packets. For details
on mark ids, see mark config helper: sanewall-mark(5).
server smtp accept mark not "20 55"
Use tos to match the TOS field on packets. For details
on TOS ids, see tos config helper: sanewall-tos(5).
server smtp accept tos not "Maximize-Throughput 0x10"
Use custom to pass arguments directly to iptables(8). All of the parameters must be in a single quoted string. To pass an option to iptables(8) that itself contains a space you need to quote strings in the usual bash(1) manner. For example:
server smtp accept custom "--some-option some-value"
server smtp accept custom "--some-option 'some-value second-value'"
Use inface and outface to
define the interface via which a request
is received and forwarded respectively.
Use the same format as interface definition: sanewall-interface(5).
Examples:
server smtp accept inface not eth0
server smtp accept inface not "eth0 eth1"
server smtp accept inface eth0 outface eth1
Use physin and physout to
define the physical interface via which a
request is received or send in cases where the inface or outface
is known to be a virtual interface; e.g. a bridge.
Use the same format as interface definition: sanewall-interface(5).
Examples:
server smtp accept physin not eth0
These parameters match information related to information gathered from the local host. They are silently ignored for incoming requests or requests that will be forwarded.
Use uid to match the operating system user sending
the traffic. The user is a username, uid number
or a quoted list of the two.
For example, to limit which users can access POP3 and IMAP:
client "pop3 imap" accept user not "user1 user2 user3"
This will allow all requests to reach the server but prevent replies unless the web server is running as apache:
server http accept user apache
Use gid to match the operating system group sending
the traffic. The group is a group name, gid
number or a quoted list of the two.
The Linux kernel infrastructure to match PID/SID and executable names with pid, sid and cmd has been removed so these options can no longer be used.
Use log or loglimit to log matching packets to syslog. Unlike iptables(8) logging, this is not an action: Sanewall will produce multiple iptables commands to accomplish both the action for the rule and the logging.
Logging is controlled using the SANEWALL_LOG_OPTIONS
and SANEWALL_LOG_LEVEL environment variables
(see control variables: sanewall-variables(5)). loglimit
additionally honours the SANEWALL_LOG_FREQUENCY and
SANEWALL_LOG_BURST variables.
Specifying level (which takes the same values as
SANEWALL_LOG_LEVEL) allows you to override the log level
for a single rule.
In addition to the commands in the synopsis, Sanewall provides limit, sport and dport which are used internally. These should not normally be used in configuration files unless you really understand what you are doing.
limit requires the arguments
frequency and
burst and will limit
the matching of traffic in both directions.
sport requires an argument
port which can be a name, number, range
(FROM:TO) or a quoted list of ports. It specifies the source port
of a request.
dport requires an argument
port which can be a name, number, range
(FROM:TO) or a quoted list of ports. It specifies the destination port
of a request.
sanewall-actions — rule actions
accept
accept with limit requests/period burst [
overflow
action
]
accept with recent name seconds hits
accept with knock name
reject [
with
message
]
drop
deny
return
tarpit
These actions are the actions to be taken on traffic that has been matched by a particular rule.
Sanewall will also pass through any actions that iptables(8) accepts, however these definitions provide lowercase versions which accept arguments where appropriate and which could otherwise not be passed through.
The iptables(8) LOG action is best used through
the optional rule parameter log since the latter
can be combined with one of these actions
(Sanewall will generate multiple firewall
rules to make this happen). For information on log
and loglimit, see optional rule parameters: sanewall-rule-params(5).
The following actions are defined:
accept allows the traffic matching the rules to reach its destination.
For example, to allow SMTP requests and their replies to flow:
server smtp accept
accept with limit allows the traffic,
with new connections limited to requests/period
with a maximum burst.
Run iptables -m limit --help for more
information.
The default overflow action is to REJECT
the excess connections (DROP would produce timeouts on otherwise
valid service clients).
Examples:
server smtp accept with limit 10/sec 100
server smtp accept with limit 10/sec 100 overflow drop
accept with recent allows the traffic
matching the rules to reach its destination, limited per
remote IP to hits per seconds.
Run iptables -m recent --help for
more information.
The name parameter is used to allow
multiple rules to share the same table of recent IPs.
For example, to allow only 2 connections every 60 seconds per remote IP, to the smtp server:
server smtp accept with recent mail 60 2
When a new connection is not allowed, the traffic will continue to be matched by the rest of the firewall. In other words, if the traffic is not allowed due to the limitations set here, it is not dropped, it is just not matched by this rule.
accept with knock allows easy integration with knockd, a server that allows you to control access to services by sending certain packets to "knock" on the door, before the door is opened for service.
The name is used to build a special chain
knock_<name> which contains rules to
allow established connections to work. If
knockd has not allowed new
connections any traffic entering this chain will just return
back and continue to match against the other rules until
the end of the firewall.
For example, to allow HTTPS requests based on a knock write:
server https accept with knock hidden
then configure knockd to enable the HTTPS service with:
iptables -A knock_hidden -s %IP% -j ACCEPT
and disable it with:
iptables -D knock_hidden -s %IP% -j ACCEPT
You can use the same knock name in more than
one Sanewall rule to enable/disable all the services based
on a single knockd configuration
entry.
There is no need to match anything other than the IP in knockd. Sanewall already matches everything else needed for its rules to work.
message, rejectreject discards the traffic matching the rules and sends a rejecting message back to the sender.
When used with with the specific message
to return can be specified. Run
iptables -j REJECT --help for a
list of the --reject-with values which
can be used for message.
See the section called “Reject With Messsages” for some examples.
The default (no message specified) is to send
tcp-reset when dealing with TCP connections
and icmp-port-unreachable for all other
protocols.
For example:
UNMATCHED_INPUT_POLICY="reject with host-prohib"
policy reject with host-unreach
server ident reject with tcp-reset
drop discards the traffic matching the rules. It does so silently and the sender will need to timeout to conclude it cannot reach the service.
deny is a synonym for drop. For example, either of these would silently discard SMTP traffic:
server smtp drop
server smtp deny
return will return the flow of processing to the parent of the current command.
Currently, the only time return can be used meaningfully used is as a policy for an interface definition. Unmatched traffic will continue being processed with the possibility of being matched by a later definition. For example:
policy return
tarpit captures and holds incoming TCP connections open.
Connections are accepted and immediately switched to the persist state (0 byte window), in which the remote side stops sending data and asks to continue every 60-240 seconds.
Attempts to close the connection are ignored, forcing the remote side to time out the connection after 12-24 minutes.
Example:
server smtp tarpit
As the kernel conntrack modules are always loaded by Sanewall, some per-connection resources will be consumed. See this bug report for details.
The following actions also exist but should not be used under normal circumstances:
mirror returns the traffic it receives by switching the source and destination fields. REJECT will be used for traffic generated by the local host.
The MIRROR target was removed from the Linux kernel due to its security implications.
MIRROR is dangerous; use it with care and only if you understand what you are doing.
portredirect is used internally by Sanewall helper commands.
Only Sanewall developers should need to use this action directly.
The following RFCs contain information relevant to these messages:
| RFC 1812 |
| RFC 1122 |
| RFC 792 |
ICMP network unreachable
Generated by a router if a forwarding path (route) to the destination network is not available.
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 792.
Use with care. The sender and the routers between you and the sender may conclude that the whole network your host resides in is unreachable, and prevent other traffic from reaching you.
ICMP host unreachable
Generated by a router if a forwarding path (route) to the destination host on a directly connected network is not available (does not respond to ARP).
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 792.
Use with care. The sender and the routers between you and the sender may conclude that your host is entirely unreachable, and prevent other traffic from reaching you.
ICMP protocol unreachable
Generated if the transport protocol designated in a datagram is not supported in the transport layer of the final destination.
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 792.
ICMP port unreachable
Generated if the designated transport protocol (e.g. TCP, UDP, etc.) is unable to demultiplex the datagram in the transport layer of the final destination but has no protocol mechanism to inform the sender.
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 792.
Generated by hosts to indicate that the required port is not active.
ICMP communication with destination network administratively prohibited
This code was intended for use by end-to-end encryption devices used by U.S. military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets.
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 1122.
This message may not be widely understood.
ICMP communication with destination host administratively prohibited
This code was intended for use by end-to-end encryption devices used by U.S. military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets.
From RFC 1812, section 5.2.7.1. See RFC 1812 and RFC 1122.
This message may not be widely understood.
TCP RST
The port unreachable message of the TCP stack.
See RFC 1122.
tcp-reset is useful when you want to prevent
timeouts on rejected TCP services where the client incorrectly
ignores ICMP port unreachable messages.
sanewall-services — Sanewall service list
This Wikipedia list of ports may be helpful if you need to define a new service.
AH - IPSec Authentication Header (AH) - simple service
Configuration sample:
server AH accept
51/any
any
For more information see this Archive of the FreeS/WAN documentation and RFC 2402.
all - Match all traffic - complex service
Configuration sample:
server all accept
all
all
Matches all traffic (all protocols, ports, etc) while ensuring that required kernel modules are loaded.
This service may indirectly setup a set of other services, if they require kernel modules to be loaded. The following complex services are activated:
| ftp - File Transfer Protocol - simple service |
| irc - Internet Relay Chat - simple service |
amanda - Advanced Maryland Automatic Network Disk Archiver - simple service
udp/10080
default
nf_conntrack_amanda (CONFIG_NF_CONNTRACK_AMANDA)
nf_nat_amanda (CONFIG_NF_NAT_AMANDA)
any - Match all traffic (without modules or indirect) - complex service
Configuration sample:
server any myname accept proto 47
all
all
Matches all traffic (all protocols, ports, etc), but does not care about kernel modules and does not activate any other service indirectly. In combination with the optional rule parameters: sanewall-rule-params(5) this service can match unusual traffic (e.g. GRE - protocol 47).
anystateless - Match all traffic statelessly - complex service
Configuration sample:
server anystateless myname accept proto 47
all
all
Matches all traffic (all protocols, ports, etc), but does not care about kernel modules and does not activate any other service indirectly. In combination with the optional rule parameters: sanewall-rule-params(5) this service can match unusual traffic (e.g. GRE - protocol 47).
This service is identical to "any" but does not care about the state of traffic.
apcupsd - APC UPS Daemon - simple service
Configuration sample:
server apcupsd accept
tcp/6544
default
This service must be defined as "server apcupsd accept" on all machines not directly connected to the UPS (i.e. slaves).
Note that the port defined here is not the default port (6666) used if you download and compile APCUPSD, since the default conflicts with IRC and many distributions (like Debian) have changed this to 6544.
You can define port 6544 in APCUPSD, by changing the value of NETPORT in its configuration file, or overwrite this Sanewall service definition using the procedures described in the section called “Adding Services” of Sanewall configuration: sanewall.conf(5).
aptproxy - Advanced Packaging Tool Proxy - simple service
Configuration sample:
server aptproxy accept
tcp/9999
default
asterisk - Asterisk PABX - simple service
Configuration sample:
server asterisk accept
tcp/5038
default
This service refers only to the manager interface of asterisk. You should normally enable sip - Session Initiation Protocol - simple service , h323 - H.323 VoIP - simple service , rtp - Real-time Transport Protocol - simple service , etc. at the firewall level, if you enable the relative channel drivers of asterisk.
custom - Custom definitions - custom service
Configuration sample:
server custom myimap tcp/143 default accept
N/A
N/A
The full syntax is:
subcommand custom name svr-proto/ports cli-ports action params
This service is used by Sanewall to allow you create rules for services which do not have a definition.
subcommand, action and params have their usual meanings.
A name must be supplied along with server
ports in the form proto/range
and client ports which takes only a
range.
To define services with the built-in extension mechanism to avoid the need for custom services, see the section called “Adding Services” of Sanewall configuration: sanewall.conf(5).
darkstat - Darkstat network traffic analyser - simple service
Configuration sample:
server darkstat accept
tcp/666
default
daytime - Daytime Protocol - simple service
Configuration sample:
server daytime accept
tcp/13
default
dcpp - Direct Connect++ P2P - simple service
Configuration sample:
server dcpp accept
tcp/1412 udp/1412
default
dhcp - Dynamic Host Configuration Protocol - complex service
Configuration sample:
server dhcp accept
udp/67
68
The dhcp service is implemented as stateless rules.
DHCP clients broadcast to the network (src 0.0.0.0 dst 255.255.255.255) to find a DHCP server. If the DHCP service was stateful the iptables connection tracker would not match the packets and deny to send the reply.
Note that this change does not affect the security of either DHCP servers or clients, since only the specific ports are allowed (there is no random port at either the server or the client side).
Note also that the "server dhcp accept" or "client dhcp accept" commands should placed within interfaces that do not have src and / or dst defined (because of the initial broadcast).
You can overcome this problem by placing the DHCP service on a separate interface, without a src or dst but with a policy return. Place this interface before the one that defines the rest of the services.
For example:
interface eth0 dhcp
policy return
server dhcp accept
interface eth0 lan src "$mylan" dst "$myip"
client all accept
dhcprelay - DHCP Relay - simple service
Configuration sample:
server dhcprelay accept
udp/67
67
From RFC 1812 section 9.1.2:
In many cases, BOOTP clients and their associated BOOTP server(s) do not reside on the same IP (sub)network. In such cases, a third-party agent is required to transfer BOOTP messages between clients and servers. Such an agent was originally referred to as a BOOTP forwarding agent. However, to avoid confusion with the IP forwarding function of a router, the name BOOTP relay agent has been adopted instead.
For more information about DHCP Relay see section 9.1.2 of RFC 1812 and section 4 of RFC 1542
distcc - Distributed CC - simple service
Configuration sample:
server distcc accept
tcp/3632
default
For distcc security, please check the distcc security design.
dns - Domain Name System - simple service
Configuration sample:
server dns accept
udp/53 tcp/53
any
On very busy DNS servers you may see a few dropped DNS packets in your logs. This is normal. The iptables connection tracker will timeout the session and lose unmatched DNS packets that arrive too late to be useful.
echo - Echo Protocol - simple service
Configuration sample:
server echo accept
tcp/7
default
emule - eMule (Donkey network client) - complex service
Configuration sample:
client emule accept src 192.0.2.1
many
many
According to eMule Port Definitions, Sanewall defines:
| Accept from any client port to the server at tcp/4661 |
| Accept from any client port to the server at tcp/4662 |
| Accept from any client port to the server at udp/4665 |
| Accept from any client port to the server at udp/4672 |
| Accept from any server port to the client at tcp/4662 |
| Accept from any server port to the client at udp/4672 |
Use the Sanewall client command: sanewall-client(5) command to match the eMule client.
Please note that the eMule client is an HTTP client also.
eserver - eDonkey network server - simple service
Configuration sample:
server eserver accept
tcp/4661 udp/4661 udp/4665
any
ESP - IPSec Encapsulated Security Payload (ESP) - simple service
Configuration sample:
server ESP accept
50/any
any
For more information see this Archive of the FreeS/WAN documentation RFC 2406.
finger - Finger Protocol - simple service
Configuration sample:
server finger accept
tcp/79
default
ftp - File Transfer Protocol - simple service
Configuration sample:
server ftp accept
tcp/21
default
nf_conntrack_ftp (CONFIG_NF_CONNTRACK_FTP)
nf_nat_ftp (CONFIG_NF_NAT_FTP)
The FTP service matches both active and passive FTP connections.
gift - giFT Internet File Transfer - simple service
Configuration sample:
server gift accept
tcp/4302 tcp/1214 tcp/2182 tcp/2472
any
The gift Sanewall service supports:
| Gnutella listening at tcp/4302 |
| FastTrack listening at tcp/1214 |
| OpenFT listening at tcp/2182 and tcp/2472 |
The above ports are the defaults given for the corresponding giFT modules.
To allow access to the user interface ports of giFT, use the giftui - giFT Internet File Transfer User Interface - simple service .
giftui - giFT Internet File Transfer User Interface - simple service
Configuration sample:
server giftui accept
tcp/1213
default
This service refers only to the user interface ports offered by giFT. To allow gift accept P2P requests, use the gift - giFT Internet File Transfer - simple service .
GRE - Generic Routing Encapsulation - simple service
Configuration sample:
server GRE accept
47/any
any
nf_conntrack_proto_gre (CONFIG_NF_CT_PROTO_GRE)
nf_nat_proto_gre (CONFIG_NF_NAT_PROTO_GRE)
Protocol No 47.
For more information see RFC RFC 2784.
h323 - H.323 VoIP - simple service
Configuration sample:
server h323 accept
tcp/1720
default
nf_conntrack_h323 (CONFIG_NF_CONNTRACK_H323)
nf_nat_h323 (CONFIG_NF_NAT_H323)
heartbeat - HeartBeat - simple service
Configuration sample:
server heartbeat accept
udp/690:699
default
This Sanewall service has been designed such a way that it will allow multiple heartbeat clusters on the same LAN.
http - Hypertext Transfer Protocol - simple service
Configuration sample:
server http accept
tcp/80
default
httpalt - HTTP alternate port - simple service
Configuration sample:
server httpalt accept
tcp/8080
default
This port is commonly used by web servers, web proxies and caches where the standard http - Hypertext Transfer Protocol - simple service port is not available or can or should not be used.
https - Secure Hypertext Transfer Protocol - simple service
Configuration sample:
server https accept
tcp/443
default
hylafax - HylaFAX - complex service
Configuration sample:
server hylafax accept
many
many
This service allows incoming requests to server port tcp/4559 and outgoing from server port tcp/4558.
The correct operation of this service has not been verified.
USE THIS WITH CARE. A HYLAFAX CLIENT MAY OPEN ALL TCP UNPRIVILEGED PORTS TO ANYONE (from port tcp/4558).
iax - Inter-Asterisk eXchange - simple service
Configuration sample:
server iax accept
udp/5036
default
This service refers to IAX version 1. There is also iax2 - Inter-Asterisk eXchange v2 - simple service .
iax2 - Inter-Asterisk eXchange v2 - simple service
Configuration sample:
server iax2 accept
udp/5469 udp/4569
default
This service refers to IAX version 2. There is also iax - Inter-Asterisk eXchange - simple service .
icmp - Internet Control Message Protocol - simple service
Configuration sample:
server icmp accept
icmp/any
any
icmpv6 - Internet Control Message Protocol v6 - simple service
Configuration sample:
server icmpv6 accept
icmpv6/any
any
icp - Internet Cache Protocol - simple service
Configuration sample:
server icp accept
udp/3130
3130
ident - Identification Protocol - simple service
Configuration sample:
server ident reject with tcp-reset
tcp/113
default
imap - Internet Message Access Protocol - simple service
Configuration sample:
server imap accept
tcp/143
default
imaps - Secure Internet Message Access Protocol - simple service
Configuration sample:
server imaps accept
tcp/993
default
ipv6error - ICMPv6 Error Handling - complex service
Configuration sample:
server ipv6error accept
N/A
N/A
A number of icmpv6 error types are not treated equally inbound and outbound.
The ipv6error rule wraps all of them in the following way:
| allow incoming messages only for existing sessions |
| allow outgoing messages always |
The following icmpv6 messages are handled:
| destination-unreachable |
| packet-too-big |
| ttl-zero-during-transit |
| ttl-zero-during-reassembly |
| unknown-header-type |
| unknown-option |
Sanewall sets up both rules the same way. In a router with inface being internal and outface being external the following will meet the recommendations of RFC 4890:
server ipv6error accept
Interfaces should always have:
server ipv6error accept
set.
Do not use:
client ipv6error accept
unless you are controlling traffic on an router interface where outface is the internal destination.
ipv6neigh - IPv6 Neighbour discovery - complex service
Configuration sample:
client ipv6neigh accept server ipv6neigh accept
N/A
N/A
ICMPv6 does a great deal of automatic configuration and discovery. There is no ARP and no need to manually configure routers. To enable this functionality the network neighbour and router solicitation/advertisement messages should be enabled on each interface.
These rules are stateless since advertisement can happen automatically as well as on solicitation.
Neighbour discovery (incoming) should always be enabled:
server ipv6neigh accept
Neighbour advertisement (outgoing) should always be enabled:
client ipv6neigh accept
The rules should not be used to pass packets across a firewall (e.g. in a router) unless it is a bridge.
ipv6router - IPv6 Router discovery - complex service
Configuration sample:
client ipv6router accept
N/A
N/A
ICMPv6 does a great deal of automatic configuration and discovery. There is no ARP and no need to manually configure routers. To enable this functionality the network neighbour and router solicitation/advertisement messages should be enabled on each interface.
These rules are stateless since advertisement can happen automatically as well as on solicitation.
Router discovery (incoming) should always be enabled:
client ipv6router accept
Router advertisement (outgoing) should be enabled on a host that routes:
server ipv6router accept
The rules should not be used to pass packets across a firewall (e.g. in a router) unless it is a bridge.
irc - Internet Relay Chat - simple service
Configuration sample:
server irc accept
tcp/6667
default
nf_conntrack_irc (CONFIG_NF_CONNTRACK_IRC)
nf_nat_irc (CONFIG_NF_NAT_IRC)
isakmp - Internet Security Association and Key Management Protocol (IKE) - simple service
Configuration sample:
server isakmp accept
udp/500
any
For more information see the Archive of the FreeS/WAN documentation
jabber - Extensible Messaging and Presence Protocol - simple service
Configuration sample:
server jabber accept
tcp/5222 tcp/5223
default
Allows clear and SSL client-to-server connections.
jabberd - Extensible Messaging and Presence Protocol (Server) - simple service
Configuration sample:
server jabberd accept
tcp/5222 tcp/5223 tcp/5269
default
Allows clear and SSL client-to-server and server-to-server connections.
Use this service for a jabberd server. In all other cases, use the jabber - Extensible Messaging and Presence Protocol - simple service .
ldap - Lightweight Directory Access Protocol - simple service
Configuration sample:
server ldap accept
tcp/389
default
ldaps - Secure Lightweight Directory Access Protocol - simple service
Configuration sample:
server ldaps accept
tcp/636
default
lpd - Line Printer Daemon Protocol - simple service
Configuration sample:
server lpd accept
tcp/515
any
LPD is documented in RFC 1179.
Since many operating systems incorrectly use the non-default client ports for LPD access, this definition allows any client port to access the service (in addition to the RFC defined 721 to 731 inclusive).
microsoft_ds - Direct Hosted (NETBIOS-less) SMB - simple service
Configuration sample:
server microsoft_ds accept
tcp/445
default
Direct Hosted (i.e. NETBIOS-less SMB)
This is another NETBIOS Session Service with minor differences with netbios_ssn - NETBIOS Session Service - simple service . It is supported only by Windows 2000 and Windows XP and it offers the advantage of being independent of WINS for name resolution.
It seems that samba supports transparently this protocol on the netbios_ssn - NETBIOS Session Service - simple service ports, so that either direct hosted or traditional SMB can be served simultaneously.
Please refer to the netbios_ssn - NETBIOS Session Service - simple service for more information.
mms - Microsoft Media Server - simple service
Configuration sample:
server mms accept
tcp/1755 udp/1755
default
See here.
See here.
Microsoft's proprietary network streaming protocol used to transfer unicast data in Windows Media Services (previously called NetShow Services).
msn - Microsoft MSN Messenger Service - simple service
Configuration sample:
server msn accept
tcp/1863 udp/1863
default
multicast - Multicast - complex service
Configuration sample:
server multicast reject with proto-unreach
N/A
N/A
The multicast service matches all packets sent to 224.0.0.0/4 using IGMP or UDP.
netbackup - Veritas NetBackup service - simple service
Configuration sample:
server netbackup accept client netbackup accept
tcp/13701 tcp/13711 tcp/13720 tcp/13721 tcp/13724 tcp/13782 tcp/13783
any
To use this service you must define it as both client and server in NetBackup clients and NetBackup servers.
netbios_dgm - NETBIOS Datagram Distribution Service - simple service
Configuration sample:
server netbios_dgm accept
udp/138
any
See also the samba - Samba - complex service .
Keep in mind that this service broadcasts (to the broadcast address of your LAN) UDP packets. If you place this service within an interface that has a dst parameter, remember to include (in the dst parameter) the broadcast address of your LAN too.
netbios_ns - NETBIOS Name Service - simple service
Configuration sample:
server netbios_ns accept
udp/137
any
See also the samba - Samba - complex service .
netbios_ssn - NETBIOS Session Service - simple service
Configuration sample:
server netbios_ssn accept
tcp/139
default
See also the samba - Samba - complex service .
Please keep in mind that newer NETBIOS clients prefer to use port 445 (microsoft_ds - Direct Hosted (NETBIOS-less) SMB - simple service ) for the NETBIOS session service, and when this is not available they fall back to port 139 (netbios_ssn). Versions of samba above 3.x bind automatically to ports 139 and 445.
If you have an older samba version and your policy on an interface or router is DROP, clients trying to access port 445 will have to timeout before falling back to port 139. This timeout can be up to several minutes.
To overcome this problem you can explicitly REJECT the microsoft_ds - Direct Hosted (NETBIOS-less) SMB - simple service with a tcp-reset message:
server microsoft_ds reject with tcp-reset
nfs - Network File System - complex service
Configuration sample:
client nfs accept dst 192.0.2.1
many
N/A
The NFS service queries the RPC service on the NFS server host to find out the ports nfsd, mountd, lockd and rquotad are listening. Then, according to these ports it sets up rules on all the supported protocols (as reported by RPC) in order the clients to be able to reach the server.
For this reason, the NFS service requires that:
| the firewall is restarted if the NFS server is restarted |
| the NFS server must be specified on all nfs statements (only if it is not the localhost) |
Since NFS queries the remote RPC server, it is required to also be allowed to do so, by allowing the portmap - Open Network Computing Remote Procedure Call - Port Mapper - simple service too. Take care that this is allowed by the running firewall when Sanewall tries to query the RPC server. So you might have to setup NFS in two steps: First add the portmap service and activate the firewall, then add the NFS service and restart the firewall.
To avoid this you can setup your NFS server to listen on pre-defined ports, as documented in NFS Howto. If you do this then you will have to define the the ports using the procedure described in the section called “Adding Services” of Sanewall configuration: sanewall.conf(5).
nis - Network Information Service - complex service
Configuration sample:
client nis accept dst 192.0.2.1
many
N/A
The nis service queries the RPC service on the nis server host to find out the ports ypserv and yppasswdd are listening. Then, according to these ports it sets up rules on all the supported protocols (as reported by RPC) in order the clients to be able to reach the server.
For this reason, the nis service requires that:
| the firewall is restarted if the nis server is restarted |
| the nis server must be specified on all nis statements (only if it is not the localhost) |
Since nis queries the remote RPC server, it is required to also be allowed to do so, by allowing the portmap - Open Network Computing Remote Procedure Call - Port Mapper - simple service too. Take care that this is allowed by the running firewall when Sanewall tries to query the RPC server. So you might have to setup nis in two steps: First add the portmap service and activate the firewall, then add the nis service and restart the firewall.
This service was added to FireHOL by Carlos Rodrigues. His comments regarding this implementation, are:
These rules work for client access only!
Pushing changes to slave servers won't work if these rules are active somewhere between the master and its slaves, because it is impossible to predict the ports where yppush will be listening on each push.
Pulling changes directly on the slaves will work, and could be improved performance-wise if these rules are modified to open fypxfrd. This wasn't done because it doesn't make that much sense since pushing changes on the master server is the most common, and recommended, way to replicate maps.
nntp - Network News Transfer Protocol - simple service
Configuration sample:
server nntp accept
tcp/119
default
nntps - Secure Network News Transfer Protocol - simple service
Configuration sample:
server nntps accept
tcp/563
default
ntp - Network Time Protocol - simple service
Configuration sample:
server ntp accept
udp/123 tcp/123
any
nut - Network UPS Tools - simple service
Configuration sample:
server nut accept
tcp/3493 udp/3493
default
nxserver - NoMachine NX Server - simple service
Configuration sample:
server nxserver accept
tcp/5000:5200
default
Default ports used by NX server for connections without encryption.
Note that nxserver also needs the ssh - Secure Shell Protocol - simple service to be enabled.
This information has been extracted from this The TCP ports used by nxserver are 4000 + DISPLAY_BASE to 4000 + DISPLAY_BASE + DISPLAY_LIMIT. DISPLAY_BASE and DISPLAY_LIMIT are set in /usr/NX/etc/node.conf and the defaults are DISPLAY_BASE=1000 and DISPLAY_LIMIT=200.
For encrypted nxserver sessions, only ssh - Secure Shell Protocol - simple service is needed.
oracle - Oracle Database - simple service
Configuration sample:
server oracle accept
tcp/1521
default
OSPF - Open Shortest Path First - simple service
Configuration sample:
server OSPF accept
89/any
any
ping - Ping (ICMP echo) - complex service
Configuration sample:
server ping accept
N/A
N/A
This services matches requests of protocol ICMP and type echo-request (TYPE=8) and their replies of type echo-reply (TYPE=0).
The ping service is stateful.
pop3 - Post Office Protocol - simple service
Configuration sample:
server pop3 accept
tcp/110
default
pop3s - Secure Post Office Protocol - simple service
Configuration sample:
server pop3s accept
tcp/995
default
portmap - Open Network Computing Remote Procedure Call - Port Mapper - simple service
Configuration sample:
server portmap accept
udp/111 tcp/111
any
postgres - PostgreSQL - simple service
Configuration sample:
server postgres accept
tcp/5432
default
pptp - Point-to-Point Tunneling Protocol - simple service
Configuration sample:
server pptp accept
tcp/1723
default
nf_conntrack_pptp (CONFIG_NF_CONNTRACK_PPTP), nf_conntrack_proto_gre (CONFIG_NF_CT_PROTO_GRE)
nf_nat_pptp (CONFIG_NF_NAT_PPTP), nf_nat_proto_gre (CONFIG_NF_NAT_PROTO_GRE)
privoxy - Privacy Proxy - simple service
Configuration sample:
server privoxy accept
tcp/8118
default
radius - Remote Authentication Dial In User Service (RADIUS) - simple service
Configuration sample:
server radius accept
udp/1812 udp/1813
default
radiusold - Remote Authentication Dial In User Service (RADIUS) - simple service
Configuration sample:
server radiusold accept
udp/1645 udp/1646
default
radiusoldproxy - Remote Authentication Dial In User Service (RADIUS) - simple service
Configuration sample:
server radiusoldproxy accept
udp/1647
default
radiusproxy - Remote Authentication Dial In User Service (RADIUS) - simple service
Configuration sample:
server radiusproxy accept
udp/1814
default
rdp - Remote Desktop Protocol - simple service
Configuration sample:
server rdp accept
tcp/3389
default
Remote Desktop Protocol is also known also as Terminal Services.
rndc - Remote Name Daemon Control - simple service
Configuration sample:
server rndc accept
tcp/953
default
rtp - Real-time Transport Protocol - simple service
Configuration sample:
server rtp accept
udp/10000:20000
any
RTP ports are generally all the UDP ports. This definition narrows down RTP ports to UDP 10000 to 20000.
samba - Samba - complex service
Configuration sample:
server samba accept
many
default
The samba service automatically sets all the rules for netbios_ns - NETBIOS Name Service - simple service , netbios_dgm - NETBIOS Datagram Distribution Service - simple service , netbios_ssn - NETBIOS Session Service - simple service and microsoft_ds - Direct Hosted (NETBIOS-less) SMB - simple service .
Please refer to the notes of the above services for more information.
NETBIOS initiates based on the broadcast address of an interface (request goes to broadcast address) but the server responds from its own IP address. This makes the "server samba accept" statement drop the server reply, because of the way the iptables connection tracker works.
This service definition includes a hack, that allows a Linux samba server to respond correctly in such situations, by allowing new outgoing connections from the well known netbios_ns - NETBIOS Name Service - simple service port to the clients high ports.
However, for clients and routers this hack is not applied because it would open all unprivileged ports to the samba server. The only solution to overcome the problem in such cases (routers or clients) is to build a trust relationship between the samba servers and clients.
sane - SANE Scanner service - simple service
tcp/6566
default
nf_conntrack_sane (CONFIG_NF_CONNTRACK_SANE)
N/A
sip - Session Initiation Protocol - simple service
Configuration sample:
server sip accept
udp/5060
5060 default
nf_conntrack_sip (CONFIG_NF_CONNTRACK_SIP)
nf_nat_sip (CONFIG_NF_NAT_SIP)
SIP is an IETF standard protocol (RFC 2543) for initiating interactive user sessions involving multimedia elements such as video, voice, chat, gaming, etc. SIP works in the application layer of the OSI communications model.
smtp - Simple Mail Transport Protocol - simple service
Configuration sample:
server smtp accept
tcp/25
default
smtps - Secure Simple Mail Transport Protocol - simple service
Configuration sample:
server smtps accept
tcp/465
default
snmp - Simple Network Management Protocol - simple service
Configuration sample:
server snmp accept
udp/161
default
snmptrap - SNMP Trap - simple service
Configuration sample:
server snmptrap accept
udp/162
any
An SNMP trap is a notification from an agent to a manager.
ssh - Secure Shell Protocol - simple service
Configuration sample:
server ssh accept
tcp/22
default
submission - SMTP over SSL/TLS submission - simple service
Configuration sample:
server submission accept
tcp/587
default
Submission is essentially normal SMTP with an SSL/TLS negotiation.
swat - Samba Web Administration Tool - simple service
Configuration sample:
server swat accept
tcp/901
default
syslog - Syslog Remote Logging Protocol - simple service
Configuration sample:
server syslog accept
udp/514
syslog default
telnet - Telnet - simple service
Configuration sample:
server telnet accept
tcp/23
default
tftp - Trivial File Transfer Protocol - simple service
Configuration sample:
server tftp accept
udp/69
default
nf_conntrack_tftp (CONFIG_NF_CONNTRACK_TFTP)
nf_nat_tftp (CONFIG_NF_NAT_TFTP)
time - Time Protocol - simple service
Configuration sample:
server time accept
tcp/37 udp/37
default
timestamp - ICMP Timestamp - complex service
Configuration sample:
server timestamp accept
N/A
N/A
This services matches requests of protocol ICMP and type timestamp-request (TYPE=13) and their replies of type timestamp-reply (TYPE=14).
The timestamp service is stateful.
uucp - Unix-to-Unix Copy - simple service
Configuration sample:
server uucp accept
tcp/540
default
vmware - vmware - simple service
Configuration sample:
server vmware accept
tcp/902
default
Used from VMWare 1 and up. See the VMWare KnowledgeBase.
vmwareauth - vmwareauth - simple service
Configuration sample:
server vmwareauth accept
tcp/903
default
Used from VMWare 1 and up. See the VMWare KnowledgeBase.
vmwareweb - vmwareweb - simple service
Configuration sample:
server vmwareweb accept
tcp/8222 tcp/8333
default
Used from VMWare 2 and up. See VMWare Server 2.0 release notes and the VMWare KnowledgeBase.
vnc - Virtual Network Computing - simple service
Configuration sample:
server vnc accept
tcp/5900:5903
default
VNC is a graphical desktop sharing protocol.
webmin - Webmin Administration System - simple service
Configuration sample:
server webmin accept
tcp/10000
default
whois - WHOIS Protocol - simple service
Configuration sample:
server whois accept
tcp/43
default
xbox - Xbox Live - complex service
Configuration sample:
client xbox accept
many
default
Definition for the Xbox live service.
See program source for contributor details.
xdmcp - X Display Manager Control Protocol - simple service
Configuration sample:
server xdmcp accept
udp/177
default
See Gnome Display Manager for a discussion about XDMCP and firewalls (Gnome Display Manager is a replacement for XDM).