## Shorewall Blacklisting/Whitelisting Support

### Tom Eastep

Copyright © 2002-2006, 2010, 2011 Thomas M. Eastep

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.

2016/04/20

### Caution

This article applies to Shorewall 4.4 and later. If you are running a version of Shorewall earlier than Shorewall 4.3.5 then please see the documentation for that release.

## Introduction

Shorewall supports two different types of blackliisting; rule-based, static and dynamic. The BLACKLIST option in /etc/shorewall/shorewall.conf controls the degree of blacklist filtering.

The BLACKLIST option lists the Netfilter connection-tracking states that blacklist rules are to be applied to (states are NEW, ESTABLISHED, RELATED, INVALID, NOTRACK). The BLACKLIST option supersedes the BLACKLISTNEWONLY option:

1. BLACKLISTNEWONLY=No -- All incoming packets are checked against the blacklist. New blacklist entries can be used to terminate existing connections.

2. BLACKLISTNEWONLY=Yes -- The blacklists are only consulted for new connection requests. Blacklists may not be used to terminate existing connections.

### Important

For automatic blacklisting based on exceeding defined threshholds, see Events.

## Rule-based Blacklisting

Beginning with Shorewall 4.4.25, the preferred method of blacklisting and whitelisting is to use the blrules file (shorewall-blrules (5)). There you have access to the DROP, ACCEPT, REJECT and WHITELIST actions, standard and custom macros as well as standard and custom actions. See shorewall-blrules (5) for details.

Example:

    #ACTION         SOURCE                  DEST                    PROTO   DPORT

    WHITELIST       net:70.90.191.126       all
    DROP            net                     all                     udp     1023:1033,1434,5948,23773
    DROP            all                     net                     udp     1023:1033
    DROP            net                     all                     tcp     57,1433,1434,2401,2745,3127,3306,3410,4899,5554,5948,6101,8081,9898,23773
    DROP            net:221.192.199.48      all
    DROP            net:61.158.162.9        all
    DROP            net:81.21.54.100        all                     tcp     25
    DROP            net:84.108.168.139      all
    DROP            net:200.55.14.18        all

Beginning with Shorewall 4.4.26, the update command supports a `-b` option that causes your legacy blacklisting configuration to use the blrules file.

## Dynamic Blacklisting

Beginning with Shorewall 4.4.7, dynamic blacklisting is enabled by setting DYNAMIC_BLACKLIST=Yes in `shorewall.conf`. Prior to that release, the feature is always enabled.

Once enabled, dynamic blacklisting doesn't use any configuration parameters but is rather controlled using /sbin/shorewall[-lite] commands. Note that to and from may only be specified when running Shorewall 4.4.12 or later.

- drop [to|from] <ip address list> - causes packets from the listed IP addresses to be silently dropped by the firewall.

- reject [to|from]<ip address list> - causes packets from the listed IP addresses to be rejected by the firewall.

- allow [to|from] <ip address list> - re-enables receipt of packets from hosts previously blacklisted by a drop or reject command.

- save - save the dynamic blacklisting configuration so that it will be automatically restored the next time that the firewall is restarted.

  Update: Beginning with Shorewall 4.4.10, the dynamic blacklist is automatically retained over stop/start sequences and over restart and reload.

- show dynamic - displays the dynamic blacklisting configuration.

- logdrop [to|from] <ip address list> - causes packets from the listed IP addresses to be dropped and logged by the firewall. Logging will occur at the level specified by the BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be at the 'info' level if no BLACKLIST_LOGLEVEL was given).

- logreject [to|from}<ip address list> - causes packets from the listed IP addresses to be rejected and logged by the firewall. Logging will occur at the level specified by the BLACKLIST_LOGLEVEL setting at the last [re]start (logging will be at the 'info' level if no BLACKLIST_LOGLEVEL was given).