access.conf - the login access control table file
file specifies (user,
network/netmask) or (user,
tty) combinations for which a login will be either accepted or refused.
When someone logs in, the file
is scanned for the first entry that matches the (user,
host) or (user,
network/netmask) combination, or, in case of non-networked logins, the first entry that matches the (user,
tty) combination. The permissions field of that table entry determines whether the login will be accepted or refused.
Each line of the login access control table has three fields separated by a ":" character (colon):
The first field, the
field, can be either a "+" character (plus) for access granted or a "-" character (minus) for access denied.
The second field, the
field, should be a list of one or more login names, group names, or
(which always matches).
The third field, the
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),
(which always matches) or
(which matches any string that does not contain a "." character). If supported by the system you can use
in host or user patterns.
operator makes it possible to write very compact rules.
The group file is searched only 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 comment line.
These are some example lines which might be specified in
should be allowed to get access via
cron, X11 terminal
+ : root : crond :0 tty1 tty2 tty3 tty4 tty5 tty6
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
should get access from network
where the term will be evaluated by string matching. But it might be better to use network/netmask instead. The same meaning of
+ : root : 192.168.201.
should be able to have access from hosts
(uses string matching also).
+ : root : foo1.bar.org foo2.bar.org
should be able to have access from domain
(uses string matching also).
+ : root : .foo.bar.org
should be denied to get access from all other sources.
- : root : ALL
and members of netgroup
should be allowed to get access from all sources. This will only work if netgroup service is available.
+ : @admins foo : ALL
should get access from IPv6 host address.
+ : john foo : 2001:4ca0:0:101::1
should get access from IPv6 net/mask.
+ : john : 2001:4ca0:0:101::/64
All other users should be denied to get access from all sources.
- : ALL : ALL
manual was provided by Guido van Rooij which was renamed to
to reflect relation to default config file.
Network address / netmask description and example text was introduced by Mike Becher <email@example.com>.