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jk_check(8) jk_check jk_check(8)


jk_check - a utility that will check a jail for security problems


jk_check jail

jk_check -v -c configfile jail


jk_check will run several tests on all files and directories in a jail. The tests are:

-test for setuid (set user id) or setgid (set group id) files

-test for file modifications, using an MD5 checksum on the file in the jail and the same file in the real root

-test for group writable or world writable directories

-test for matching user information in the jail and on the real system

It will test directories based on the config file /etc/jailkit/jk_check.ini but also based on jail patterns (dir/./dir) found in the home directories in /etc/passwd


Minimal configfile

The most minimal configuration looks like:


This will include all the files and directories in /home/testchroot for testing.

More extended configfile

Often you want to ignore some tests on some directories, the following configfile shows some examples:

ignorepatheverywhere =
ignorepathoncompare = /home/testchroot/home, /home/testchroot/etc
ignorewritableforgroup = /home/testchroot/home
ignorewritableforothers = /home/testchroot/home/tmp
ignoresetuidexecuteforuser = /home/testchroot/usr/bin/smbmnt
ignoresetuidexecuteforgroup = /home/testchroot/usr/bin/smbmnt
ignoresetuidexecuteforothers =


no single test is performed in these directories. You should not use this option unless you what you are doing.
files in listed directories are not compared with their non-jail counterparts. Useful for directories like /etc/ and /home/ where you know you'll have different files inside the jail and outside the jail
listed directories that are writable for the group are not reported
listed directories that are writable for others are not reported
ignore the setuid bit on a file that is executable for a user, a file with -rws------ permissions that is. Use with care! Remember that user root can break out of a jail, therefore any program running with root privileges is theoretically capable of breaking out of the jail!
ignore the setuid bit for a file that is executable for the group, a file with -rws--x--- permissions that is.
ignore the setuid bit for a file that is executable for others, a file with -rws--x--x permissions that is


Will give verbose output
Use alternative configfile
The help screen




jailkit(8) jk_chrootlaunch(8) jk_chrootsh(8) jk_cp(8) jk_init(8) jk_jailuser(8) jk_list(8) jk_lsh(8) jk_procmailwrapper(8) jk_socketd(8) jk_uchroot(8) jk_update(8) chroot(2)


Copyright (C) 2003, 2004, 2005, 2006, 2007, Olivier Sessink

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

07-02-2010 JAILKIT