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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | MODULE TYPES PROVIDED | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHOR | COLOPHON |
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PAM_LISTFILE(8) Linux-PAM Manual PAM_LISTFILE(8)
pam_listfile - deny or allow services based on an arbitrary file
pam_listfile.so item=[tty|user|rhost|ruser|group|shell]
sense=[allow|deny] file=/path/filename
onerr=[succeed|fail] [apply=[user|@group]]
[quiet]
pam_listfile is a PAM module which provides a way to deny or
allow services based on an arbitrary file.
The module gets the item of the type specified -- user specifies
the username, PAM_USER; tty specifies the name of the terminal
over which the request has been made, PAM_TTY; rhost specifies
the name of the remote host (if any) from which the request was
made, PAM_RHOST; and ruser specifies the name of the remote user
(if available) who made the request, PAM_RUSER -- and looks for
an instance of that item in the file=filename. filename contains
one line per item listed. If the item is found, then if
sense=allow, PAM_SUCCESS is returned, causing the authorization
request to succeed; else if sense=deny, PAM_AUTH_ERR is returned,
causing the authorization request to fail.
If an error is encountered (for instance, if filename does not
exist, or a poorly-constructed argument is encountered), then if
onerr=succeed, PAM_SUCCESS is returned, otherwise if onerr=fail,
PAM_AUTH_ERR or PAM_SERVICE_ERR (as appropriate) will be
returned.
An additional argument, apply=, can be used to restrict the
application of the above to a specific user (apply=username) or a
given group (apply=@groupname). This added restriction is only
meaningful when used with the tty, rhost and shell items.
Besides this last one, all arguments should be specified; do not
count on any default behavior.
No credentials are awarded by this module.
item=[tty|user|rhost|ruser|group|shell]
What is listed in the file and should be checked for.
sense=[allow|deny]
Action to take if found in file, if the item is NOT found in
the file, then the opposite action is requested.
file=/path/filename
File containing one item per line. The file needs to be a
plain file and not world writable.
onerr=[succeed|fail]
What to do if something weird happens like being unable to
open the file.
apply=[user|@group]
Restrict the user class for which the restriction apply. Note
that with item=[user|ruser|group] this does not make sense,
but for item=[tty|rhost|shell] it have a meaning.
quiet
Do not treat service refusals or missing list files as errors
that need to be logged.
All module types (auth, account, password and session) are
provided.
PAM_AUTH_ERR
Authentication failure.
PAM_BUF_ERR
Memory buffer error.
PAM_IGNORE
The rule does not apply to the apply option.
PAM_SERVICE_ERR
Error in service module.
PAM_SUCCESS
Success.
Classic 'ftpusers' authentication can be implemented with this
entry in /etc/pam.d/ftpd:
#
# deny ftp-access to users listed in the /etc/ftpusers file
#
auth required pam_listfile.so \
onerr=succeed item=user sense=deny file=/etc/ftpusers
Note, users listed in /etc/ftpusers file are (counterintuitively)
not allowed access to the ftp service.
To allow login access only for certain users, you can use a
/etc/pam.d/login entry like this:
#
# permit login to users listed in /etc/loginusers
#
auth required pam_listfile.so \
onerr=fail item=user sense=allow file=/etc/loginusers
For this example to work, all users who are allowed to use the
login service should be listed in the file /etc/loginusers.
Unless you are explicitly trying to lock out root, make sure that
when you do this, you leave a way for root to log in, either by
listing root in /etc/loginusers, or by listing a user who is able
to su to the root account.
pam.conf(5), pam.d(5), pam(8)
pam_listfile was written by Michael K. Johnson
<johnsonm@redhat.com> and Elliot Lee <sopwith@cuc.edu>.
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
man-pages@man7.org
Linux-PAM Manual 12/22/2023 PAM_LISTFILE(8)
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HTML rendering created 2023-12-22 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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