Query: smrsh
OS: centos
Section: 8
Format: Original Unix Latex Style Formatted with HTML and a Horizontal Scroll Bar
SMRSH(8) System Manager's Manual SMRSH(8)NAMEsmrsh - restricted shell for sendmailSYNOPSISsmrsh -c commandDESCRIPTIONThe smrsh program is intended as a replacement for sh for use in the ``prog'' mailer in sendmail(8) configuration files. It sharply limits the commands that can be run using the ``|program'' syntax of sendmail in order to improve the over all security of your system. Briefly, even if a ``bad guy'' can get sendmail to run a program without going through an alias or forward file, smrsh limits the set of programs that he or she can execute. Briefly, smrsh limits programs to be in a single directory, by default /etc/smrsh, allowing the system administrator to choose the set of acceptable commands, and to the shell builtin commands ``exec'', ``exit'', and ``echo''. It also rejects any commands with the characters ``', `<', `>', `;', `$', `(', `)', ` ' (carriage return), or ` ' (newline) on the command line to prevent ``end run'' attacks. It allows ``||'' and ``&&'' to enable commands like: ``"|exec /usr/local/bin/filter || exit 75"'' Initial pathnames on programs are stripped, so forwarding to ``/usr/ucb/vacation'', ``/usr/bin/vacation'', ``/home/server/mydir/bin/vaca- tion'', and ``vacation'' all actually forward to ``/etc/smrsh/vacation''. System administrators should be conservative about populating the /etc/smrsh directory. For example, a reasonable additions is vaca- tion(1), and the like. No matter how brow-beaten you may be, never include any shell or shell-like program (such as perl(1)) in the /etc/smrsh directory. Note that this does not restrict the use of shell or perl scripts in the sm.bin directory (using the ``#!'' syntax); it simply disallows execution of arbitrary programs. Also, including mail filtering programs such as procmail(1) is a very bad idea. procmail(1) allows users to run arbitrary programs in their procmailrc(5).FILES/etc/smrsh - directory for restricted programsSEE ALSOsendmail(8) $Date: 2004/08/06 03:55:35 $ SMRSH(8)
Related Man Pages |
---|
smrsh(8) - centos |
vacation(1) - suse |
vacation(1) - netbsd |
vacation(1) - freebsd |
mailer.conf(5) - freebsd |
Similar Topics in the Unix Linux Community |
---|
Printing in Bold |
perl linux file name validation |
Split email message with procmail |
Sequence generation in shell |
Need help on how to execute several programs |