PAM_ABL.CONF(5) 						 Linux-PAM Manual						   PAM_ABL.CONF(5)

NAME

       pam_abl.conf - Configuration file for pam_abl PAM module.

SYNOPSIS

       Configuration file for both the pam_abl(8) PAM module, and the pam_abl(1) command line tool.

DESCRIPTION

   Syntax
	   word        ::= /[^s|/*]+/
	   name        ::= word | '*'
	   username    ::= name
	   servicename ::= name
	   userservice ::= username
		       |   username '/' servicename
	   namelist    ::= userservice
		       |   userservice '|' namelist
	   userspec    ::= namelist
		       |   '!' namelist
	   multiplier  ::= 's' | 'm' | 'h' | 'd'
	   number      ::= /d+/
	   period      ::= number
		       |   number multiplier
	   trigger     ::= number '/' period
	   triglist    ::= trigger
		       |   trigger ',' triglist
	   userclause  ::= userspec ':' triglist
	   rule        ::= userclause
		       |   userclause /s+/ rule

   Rule syntax
       Each rule consists of a number of space separated user clauses. A user clause specifies the user (and service) names to match and a set of
       triggers. A simple example would be

	   *:10/1h

       which means block any user () if they are responsible for ten or more failed authentication attempts in the last hour. In place of the
       which matches any user a list of usernames can be supplied like this

	   root|dba|admin:10/1h

       which means block the users root, dba and admin if they are responsible for ten or more failed authentication attempts in the last hour.
       You can also specify a service name to match against like this

	   root/sshd|dba/*:3/1d

       which means block the users root for service 'sshd and dba for any service if they are responsible for three or more failed authentication
       attempts in the last day'. Finally you can specify multiple triggers like this

	   root:10/1h,20/1d

       which means 'block the user root if they are responsible for ten or more failed attempts in the last hour or twenty or more failed attempts
       in the last day.

       Multiple rules can be provided separated by spaces like this

	   *:10/1h root:5/1h,10/1d

       in which case all rules that match a particular user and service will be checked. The user or host will be blocked if any of the rule
       triggers matches. The sense of the user matching can be inverted by placing a ! in front of the rule so that

	   !root:20/1d

       is a rule which would match for all users apart from root. It is important to treat root as a special case in the user_rule otherwise
       excessive attempts to authenticate as root will result in the root account being locked out even for valid holders of root credentials. The
       config file can contain any arguments that would be supplied via PAM config. In the config file arguments are placed on separate lines.
       Comments may be included after a # and line continuation is possible by placing a back slash at the end of the line to be continued. Here
       is a sample /etc/security/pam_abl.conf:

	   # /etc/security/pam_abl.conf
	   debug
	   host_db=/var/lib/abl/hosts.db
	   host_purge=2d
	   host_rule=*:10/1h,30/1d
	   user_db=/var/lib/abl/users.db
	   user_purge=2d
	   user_rule=!root:10/1h,30/1d

       All of the standard PAM arguments (debug, expose_account, no_warn, try_first_pass, use_first_pass, use_mapped_pass) are accepted; with the
       exception of debug and no_warn these are ignored.

       The arguments that are specific to the PAM module are as follows:

       host_db, user_db
	   Specify the name of the databases that will be used to log failed authentication attempts. The host database is used to log the
	   hostname responsible for a failed auth and the user database is used to log the requested username. If host_db or user_db is omitted
	   the corresponding auto blacklisting will be disabled.

       host_purge, user_purge
	   Specify the length of time for which failed attempts should be kept in the databases. For rules to work correctly this must be at least
	   as long as the longest period specified in a corresponding rule. You may wish to retain information about failed attempts for longer
	   than this so that the pam_abl command line tool can report information over a longer period of time. The format for this item is a
	   number with an optional multiplier suffix, s, m, h or d which correspond with seconds, minutes, hours and days. To specify seven days
	   for example one would use 7d. Note that in normal operation pam_abl will only purge the logged data for a particular host or user if it
	   happens to be updating it, i.e. if that host or user makes another failed attempt. To purge all old entries the pam_abl command line
	   tool should be used.

       host_rule, user_rule
	   These are the rules which determine the circumstances under which accounts are auto-blacklisted. The host_rule is used to block access
	   to hosts that are responsible for excessive authentication failures and the user_rule is used to disable accounts for which there have
	   been excessive authentication failures. The rule syntax is described in full below.

       host_clr_cmd, host_blk_cmd, user_clr_cmd, user_blk_cmd
	   These specify commands that will run during a check when an item switches state since its last check.

	   host_clr_cmd and user_clr_cmd will run if the host or user is currently allowed access. host_blk_cmd and user_blk_cmd are run if the
	   host or user is currentlybeing blocked by their respective rules. If no command is specified, no action is taken.

	   Within the commands, you can specify substitutions with %h, %u and %s, which will be replace with the host name, user name and service
	   currently being checked. If there isn't enough information to fulfill the requested substitutions (eg. running the pam_abl tool without
	   specifying all the necessary fields), the command will simply not run.

EXAMPLE

	   # /etc/security/pam_abl.conf
	   debug
	   host_db=/var/lib/abl/hosts.db
	   host_purge=2d
	   host_rule=*:10/1h,30/1d
	   host_blk_cmd=iptables -I INPUT -s %h -j DROP
	   user_db=/var/lib/abl/users.db
	   user_purge=2d
	   user_rule=!root:10/1h,30/1d
	   user_clr_cmd=logger This is a pointless command! user: %u host: %h service: %s

SEE ALSO

       pam_abl.conf(5), pam_abl(1)

AUTHORS

       Andy Armstrong <andy@hexten.net>

       Chris Tasma <pam-abl@deksai.com>

GNU
								    01/13/2010							   PAM_ABL.CONF(5)