access.conf(5) — Linux manual page


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

NAME         top

       access.conf - the login access control table file

DESCRIPTION         top

       The /etc/security/access.conf file specifies (user/group, host),
       (user/group, network/netmask), (user/group, tty), (user/group,
       X-$DISPLAY-value), or (user/group, pam-service-name) 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, or in the case of non-networked logins without a
       tty, the first entry that matches the (user/group,
       X-$DISPLAY-value) or (user/group, pam-service-name/) 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 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), X $DISPLAY values or
       PAM service names (for non-networked logins without a tty), 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. The
       LOCAL keyword matches if and only if pam_get_item(3), when called
       with an item_type of PAM_RHOST, returns NULL or an empty string
       (and therefore the origins field is compared against the return
       value of pam_get_item(3) called with an item_type of PAM_TTY or,
       absent that, 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

       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 comment line.

EXAMPLES         top

       These are some example lines which might be specified in

       User root should be allowed to get access via cron, X11 terminal
       :0, tty1, ..., tty5, tty6.

       +: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.



       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 or


       User root should be able to have access from hosts
       and (uses string matching also).

       User root should be able to have access from domain
       (uses string matching also).

       User root should be denied to get access from all other sources.


       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.


       Members of group wheel should be allowed to get access from all


       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.


NOTES         top

       The default separators of list items in a field are space, ',',
       and tabulator characters. Thus conveniently if spaces are put at
       the beginning and the end of the fields they are ignored. However
       if the list separator is changed with the listsep option, the
       spaces will become part of the actual item and the line will be
       most probably ignored. For this reason, it is not recommended to
       put spaces around the ':' characters.

SEE ALSO         top

       pam_access(8), pam.d(5), pam(8)

AUTHORS         top

       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 <>.

COLOPHON         top

       This page is part of the linux-pam (Pluggable Authentication
       Modules for Linux) project.  Information about the project can be
       found at ⟨⟩.  If you have a bug report
       for this manual page, see ⟨//⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Linux-PAM Manual               12/22/2023                 ACCESS.CONF(5)

Pages that refer to this page: access.conf(5)pam_access(8)