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NAME | DESCRIPTION | EXAMPLES | NOTES | SEE ALSO | AUTHORS | COLOPHON |
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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), (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):
permission:users/groups:origins
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
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 comment line.
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, 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.
+: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 also).
+: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
Members of group wheel should be allowed to get access from all
sources.
+:(wheel):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.
-:ALL:ALL
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.
pam_access(8), pam.d(5), pam(8)
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 <[email protected]>.
This page is part of the linux-pam (Pluggable Authentication
Modules for Linux) project. Information about the project can be
found at ⟨http://www.linux-pam.org/⟩. If you have a bug report
for this manual page, see ⟨//www.linux-pam.org/⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/linux-pam/linux-pam.git⟩ 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
[email protected]
Linux-PAM Manual 12/22/2023 ACCESS.CONF(5)
Pages that refer to this page: access.conf(5), pam_access(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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