=head1 NAME

aklog - Obtain tokens for authentication to AFS

=head1 SYNOPSIS

=for html
<div class="synopsis">

B<aklog> [B<-d>] [B<-hosts>] [B<-zsubs>] [B<-noprdb>] [B<-noauth>] [B<-linked>]
    [B<-force>] [B<-524>] [B<-setpag>]
    S<<< [[B<-cell> | B<-c>] <I<cell>> [B<-k> <I<Kerberos realm>>]]+ >>>

B<aklog> [B<-d>] [B<-hosts>] [B<-zsubs>] [B<-noprdb>] [B<-noauth>] [B<-linked>]
    [B<-force>] [B<-524>] [B<-setpag>] [B<-path> | B<-p>] <I<path>>+

=for html
</div>

=head1 DESCRIPTION

The B<aklog> program authenticates to a cell in AFS by obtaining AFS
tokens using a Kerberos 5 ticket. If B<aklog> is invoked with no
command-line arguments, it will obtain tokens for the workstation's local
cell.  It may be invoked with an arbitrary number of cells and pathnames
to obtain tokens for multiple cells.  B<aklog> knows how to expand cell
name abbreviations, so cells can be referred to by enough letters to make
the cell name unique among the cells the workstation knows about.

B<aklog> obtains tokens by obtaining a Kerberos service ticket for the AFS
service and then storing it as a token.  By default, it obtains that
ticket from the realm corresponding to that cell (the uppercase version of
the cell name), but a different realm for a particular cell can be
specified with B<-k>.  B<-k> cannot be used in B<-path> mode (see below).

When a Kerberos 5 cross-realm trust is used, B<aklog> looks up the AFS ID
corresponding to the name (Kerberos principal) of the person invoking the
command, and if the user doesn't exist and the
C<system:authuser@FOREIGN.REALM> PTS group exists, then it attempts automatic
registration of the user with the foreign cell.  The user is then added to
the C<system:authuser@FOREIGN.REALM> PTS group if registration is successful.
Automatic registration in the foreign cell will fail if the group quota
for the C<system:authuser@FOREIGN.REALM> group is less than one.  Each
automatic registration decrements the group quota by one.

=head1 CAUTIONS

When using B<aklog>, be aware that AFS uses the Kerberos v4 principal
naming format, not the Kerberos v5 format, when referring to principals in
PTS ACLs, F<UserList>, and similar locations.  AFS will internally map
Kerberos v5 principal names to the Kerberos v4 syntax by removing any
portion of the instance after the first period (generally the domain name
of a host principal), changing any C</> to C<.>, and changing an initial
principal part of C<host> to C<rcmd>.  In other words, to create a PTS
entry for the Kerberos v5 principal C<user/admin>, refer to it as
C<user.admin>, and for the principal C<host/shell.example.com>, refer to
it as C<rcmd.shell>.

The B<aklog> mapping of Kerberos v5 principal to Kerberos v4 principal and
the determination that a Kerberos realm is foreign is performed in the
absence of the actual AFS server configuration.  If the B<aklog> mapping
of Kerberos v5 principal to Kerberos v4 principal or the foreign realm
determination is wrong, the PTS name-to-id lookup will produce the wrong
AFS ID for the user.  The AFS ID is only used for display purposes and
should not be trusted.  Use the B<-noprdb> switch to disable the PTS
name-to-id lookup.

=head1 OPTIONS

=over 4

=item B<-524>

Normally, B<aklog> generates native K5 tokens.  This flag tells B<aklog>
to instead use the krb524 translation service to generate K4 or rxkad2b
tokens, which may be necessary for AFS cells that don't support native K5
tokens.  Support for native K5 tokens were added in OpenAFS 1.2.8.

=item B<-cell> <I<cell>>, B<-c> <I<cell>>

This flag tells B<aklog> that the next argument is the name of a cell to
authenticate to.  It normally isn't necessary; B<aklog> normally
determines whether an argument is a cell or a path name based on whether
it contains C</> or is C<.> or C<..>.  The cell may be followed by B<-k>
to specify the corresponding Kerberos realm.

=item B<-d>

Turns on printing of debugging information.  This option is not intended
for general users.

=item B<-force>

Normally, aklog will not replace tokens with new tokens that appear to be
identical.  If this flag is given, it will skip that check.

=item B<-hosts>

Prints all the server addresses which may act as a single point of failure
in accessing the specified directory path.  Each element of the path is
examined, and as new volumes are traversed, if they are not replicated,
the server's IP address containing the volume will be displayed.  The
output is of the form:

    host: <ip-address>

This option is only useful in combination with paths as arguments rather
than cells.

=item B<-k> <I<Kerberos realm>>

This flag is valid only immediately after the name of the cell.  It tells
B<aklog> to use that Kerberos realm when authenticating to the preceding
cell.  By default, B<aklog> will use the realm (per the local Kerberos
configuration) of the first database server in the cell, so this flag
normally won't be necessary.

=item B<-linked>

If the AFS cell is linked to a DCE cell, get tokens for both.

=item B<-noauth>

Don't actually authenticate, just do everything else B<aklog> does up to
setting tokens.

=item B<-noprdb>

Ordinarily, B<aklog> looks up the AFS ID corresponding to the name of the
person invoking the command, and if the user doesn't exist, the cell is a
foreign one, the system:authuser@FOREIGN.REALM PTS group exists, and has a
positive group quota, then it attempts automatic registration of the user
with the foreign cell.  Specifying this flag turns off this functionality.
This may be desirable if the protection database is unavailable for some
reason and tokens are desired anyway, or if one wants to disable user
registration.

=item B<-path> <I<pathname>>, B<-p> <I<pathname>>

This flag tells B<aklog> that the next argument is a path in AFS.
B<aklog> will walk that path and obtain tokens for every cell needed to
access all of the directories.  Normally, this flag isn't necessary;
B<aklog> assumes an argument is a path if it contains C</> or is C<.> or
C<..>.

=item B<-setpag>

When setting tokens, attempt to put the parent process in a new PAG.  This
is usually used as part of the login process but can be used any time to
create a new AFS authentication context.  Note that this in some cases
relies on dangerous and tricky manipulations of kernel records and will
not work on all platforms or with all Linux kernels.

=item B<-zsubs>

Prints out the Zephyr subscription information to get alerts regarding all
of the file servers required to access a particular path.  The output is
of the form:

    zsub: <instance>

where <instance> is the instance of a class C<filsrv> Zephyr subscription.

=back

=head1 ENVIRONMENT

=over 4

=item KRB5CCNAME

As with most programs that use an existing Kerberos ticket cache, B<aklog>
can be told to use a cache other than the default by setting the
environment variable KRB5CCNAME.  On UNIX and Linux systems, this variable
is normally set to a file name, but may point to other types of caches.
See the documentation of your Kerberos implementation for more details.

=back

=head1 FILES

=over 4

=item F<~/.xlog>

If this file exists in the user's home directory, it should contain a list
of AFS cells to which to authenticate, one per line.  If B<aklog> is
invoked without any options, it will attempt to obtain tokens in every
cell listed in this file if it exists, rather than only obtaining tokens
for the local cell.

=back

=head1 EXIT CODES

The exit status of B<aklog> will be one of the following:

=over 3

=item C<0>

Success -- No error occurred.

=item C<1>

Usage -- Bad command syntax; accompanied by a usage message.

=item C<2>

Something failed -- More than one cell or pathname was given on the
command line and at least one failure occurred.  A more specific error
status is returned when only one directive is given.

=item C<3>

AFS -- Unable to get AFS configuration or unable to get information about
a specific cell.

=item C<4>

Kerberos -- Unable to get tickets for authentication.

=item C<5>

Token -- Unable to get tokens.

=item C<6>

Bad pathname -- The path given was not a directory or lstat(2) failed on
some component of the pathname.

=item C<7>

Miscellaneous -- An internal failure occurred.  For example, B<aklog>
returns this if it runs out of memory.

=back

=head1 EXAMPLES

To get tokens for the local cell:

    % aklog

To get tokens for the C<athena.mit.edu> cell:

    % aklog athena.mit.edu

or

    % aklog athena

The latter will work if you local cache manager already knows about the
C<athena> cell.

To get tokens adequate to read F</afs/athena.mit.edu/user/p/potato>:

    % aklog /afs/athena.mit.edu/user/p/potato

To get tokens for C<testcell.mit.edu> that is in a test Kerberos realm:

    % aklog testcell.mit.edu -k TESTREALM.MIT.EDU

=head1 SEE ALSO

kinit(1), tokens(1), unlog(1)

=head1 AUTHOR

Manpage originally written by Emanuel Jay Berkenbilt (MIT-Project
Athena).  Extensively modified by Russ Allbery <rra@stanford.edu>.

=head1 COPYRIGHT

Original manpage is copyright 1990, 1991 Massachusetts Institute of
Technology.  All rights reserved.

Copyright 2006 Russ Allbery <rra@stanford.edu>.

Export of this software from the United States of America may require
a specific license from the United States Government.  It is the
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obtain such a license before exporting.

WITHIN THAT CONSTRAINT, permission to use, copy, modify, and distribute
this software and its documentation for any purpose and without fee is
hereby granted, provided that the above copyright notice appear in all
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appear in supporting documentation, and that the name of M.I.T. not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.  Furthermore if you
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without express or implied warranty.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

=cut
