NAME

       jk_lsh - a shell that limits the binaries it will execute

SYNOPSIS

       jk_lsh -c command

DESCRIPTION

       The  jailkit  limited  shell  jk_lsh is not an interactive shell. jk_lsh will only execute
       commands that are passed during startup (e.g. /bin/sh -c command) and will deny  to  start
       all  but  explicitly  allowed  commands.  All  other commands, or regular shell access are
       denied. This can be used to restrict an account to a specific use. For example, jk_lsh can
       be  used  to  make  rsync-,  cvs-, sftp- or scp-only accounts, or even an account that can
       start firefox or opera but nothing else.

       The allowed actions are read from /etc/jailkit/jk_lsh.ini  If  you  run  jk_lsh  inside  a
       changed root jail, make sure jk_lsh.ini is present inside that chroot jail.

LIMITATIONS

       Some  shells  can  process complex commandlines, such as command1 && command2, or kill `ps
       |grep foo`. The limited shell jk_lsh cannot do anything like that, another shell should be
       used  if  you  want  enable such features. It is not planned to include this in any future
       version.

OPTIONS

       jk_lsh can do word expansion such as *.txt expanding to each file  that  ends  with  .txt.
       This  is  very  useful  when running rsync or scp with jk_lsh. Option allow_word_expansion
       should be set to 1 in order to allow this.

       jk_lsh can also set environment variables. This is a comma separated list  with  key=value
       pairs.

       Options  can be set for a specific user, for the primary group of a user, or for all users
       in section DEFAULT.

EXAMPLE

       An example config file for user test or group test is shown below

       [DEFAULT]
       executables = /usr/bin/scp, /usr/lib/sftp-server, /usr/bin/rsync
       paths = /usr/bin/, /usr/lib
       allow_word_expansion = 1

       [test]
       executables = /usr/bin/scp, /usr/lib/sftp-server
       paths = /usr/bin/, /usr/lib
       allow_word_expansion = 0
       umask = 002

       [group test]
       executables = /usr/bin/rsync
       paths = /usr/bin/
       allow_word_expansion = 1
       environment=TERM=linux,FOO=bar

       If user test has primary group test, however, he  can  not  execute  rsync  in  the  above
       example.  First  the  user  section  is  checked, and only if no user section is found the
       primary group section is looked for, and only if no group section is  found,  the  DEFAULT
       section is looked for. If no section is found, jk_lsh aborts.

       The  executables entry specifies all executables that jk_lsh will execute. The paths entry
       specifies in which directories jk_lsh will look  for  these  executables  if  no  path  is
       specified. The PATH environment variable is ignored by jk_lsh. The allow_word_expansion if
       set to 1, will make jk_lsh do word expansion (*, ?, ~, $) using wordexp(3) which  is  very
       useful for remote commands like rsync server:./* .  or scp server:somedir/* /tmp/ umask if
       you want a specific umask

       The common way to use jk_lsh is to use it as default shell for those restricted  accounts.
       It is recommended to run these accounts inside a changed root using jk_chrootsh(8)

FILES

       /etc/jailkit/jk_lsh.ini /etc/passwd JAIL/etc/jailkit/jk_lsh.ini JAIL/etc/passwd

DIAGNOSTICS

       jk_lsh  logs errors to syslog, so check your log files. If you run jk_lsh inside a changed
       root, you have to have a /dev/log  in  that  changed  root.  See  jk_socketd(8)  for  more
       information how to do this.

SEE ALSO

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

COPYRIGHT

       Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 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.