December 01, 2004

rbash - RESTRICTED SHELL

If you want to restrict someone's shell access, use rbash.

chsh -s /bin/rbash username

ref. man bash

RESTRICTED SHELL

If bash is started with the name rbash, or the -r option is supplied at
invocation, the shell becomes restricted. A restricted shell is used
to set up an environment more controlled than the standard shell. It
behaves identically to bash with the exception that the following are
disallowed or not performed:

  • changing directories with cd
  • setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV
  • specifying command names containing /
  • specifying a file name containing a / as an argument to the .
    builtin command
  • Specifying a filename containing a slash as an argument to the
    -p option to the hash builtin command
  • importing function definitions from the shell environment at
    startup
  • parsing the value of SHELLOPTS from the shell environment at
    startup
  • redirecting output using the >, >|, <>, >&, &>, and >>
    redirection operators
  • using the exec builtin command to replace the shell with another
    command
  • adding or deleting builtin commands with the -f and -d options
    to the enable builtin command
  • Using the enable builtin command to enable disabled shell
    builtins
  • specifying the -p option to the command builtin command
  • turning off restricted mode with set +r or set +o restricted.

    These restrictions are enforced after any startup files are read.
    When a command that is found to be a shell script is executed (see COM-
    MAND EXECUTION above), rbash turns off any restrictions in the shell
    spawned to execute the script.

    Posted by pank at December 1, 2004 12:27 AM
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