ACCESS.CONF(5) Linux-PAM Manual ACCESS.CONF(5)
access.conf - the login access control table file
The /etc/security/access.conf file specifies (user/group, host), (user/group,
network/netmask) or (user/group, tty) combinations for which a login will be either
accepted or refused.
When someone logs in, the file access.conf is scanned for the first entry that matches the
(user/group, host) or (user/group, network/netmask) combination, or, in case of
non-networked logins, the first entry that matches the (user/group, tty) combination. The
permissions field of that table entry determines whether the login will be accepted or
Each line of the login access control table has three fields separated by a ":" character
The first field, the permission field, can be either a "+" character (plus) for access
granted or a "-" character (minus) for access denied.
The second field, the users/group field, should be a list of one or more login names,
group names, or ALL (which always matches). To differentiate user entries from group
entries, group entries should be written with brackets, e.g. (group).
The third field, the origins field, should be a list of one or more tty names (for
non-networked logins), host names, domain names (begin with "."), host addresses, internet
network numbers (end with "."), internet network addresses with network mask (where
network mask can be a decimal number or an internet address also), ALL (which always
matches) or LOCAL. LOCAL keyword matches if and only if the PAM_RHOST is not set and
<origin> field is thus set from PAM_TTY or PAM_SERVICE". If supported by the system you
can use @netgroupname in host or user patterns. The @@netgroupname syntax is supported in
the user pattern only and it makes the local system hostname to be passed to the netgroup
match call in addition to the user name. This might not work correctly on some libc
implementations causing the match to always fail.
The EXCEPT operator makes it possible to write very compact rules.
If the nodefgroup is not set, the group file is searched when a name does not match that
of the logged-in user. Only groups are matched in which users are explicitly listed.
However the PAM module does not look at the primary group id of a user.
The "#" character at start of line (no space at front) can be used to mark this line as a
These are some example lines which might be specified in /etc/security/access.conf.
User root should be allowed to get access via cron, X11 terminal :0, tty1, ..., tty5,
+ : root : crond :0 tty1 tty2 tty3 tty4 tty5 tty6
User root should be allowed to get access from hosts which own the IPv4 addresses. This
does not mean that the connection have to be a IPv4 one, a IPv6 connection from a host
with one of this IPv4 addresses does work, too.
+ : root : 192.168.200.1 192.168.200.4 192.168.200.9
+ : root : 127.0.0.1
User root should get access from network 192.168.201. where the term will be evaluated by
string matching. But it might be better to use network/netmask instead. The same meaning
of 192.168.201. is 192.168.201.0/24 or 192.168.201.0/255.255.255.0.
+ : root : 192.168.201.
User root should be able to have access from hosts foo1.bar.org and foo2.bar.org (uses
string matching also).
+ : root : foo1.bar.org foo2.bar.org
User root should be able to have access from domain foo.bar.org (uses string matching
+ : root : .foo.bar.org
User root should be denied to get access from all other sources.
- : root : ALL
User foo and members of netgroup admins should be allowed to get access from all sources.
This will only work if netgroup service is available.
+ : @admins foo : ALL
User john and foo should get access from IPv6 host address.
+ : john foo : 2001:db8:0:101::1
User john should get access from IPv6 net/mask.
+ : john : 2001:db8:0:101::/64
Disallow console logins to all but the shutdown, sync and all other accounts, which are a
member of the wheel group.
-:ALL EXCEPT (wheel) shutdown sync:LOCAL
All other users should be denied to get access from all sources.
- : ALL : ALL
pam_access(8), pam.d(5), pam(7)
Original login.access(5) manual was provided by Guido van Rooij which was renamed to
access.conf(5) to reflect relation to default config file.
Network address / netmask description and example text was introduced by Mike Becher
Linux-PAM Manual 06/04/2011 ACCESS.CONF(5)