smrsh - restricted shell for sendmail smrsh
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System Administration Commands smrsh(1M) NAME smrsh - restricted shell for sendmail SYNOPSIS smrsh -c command DESCRIPTION The smrsh program is intended as a replacement for the sh command in the prog mailer in sendmail(1M) configuration files. The smrsh program sharply limits commands that can be run using the |program syntax of sendmail. This improves overall system security. smrsh limits the set of programs that a programmer can execute, even if sendmail runs a pro- gram without going through an alias or forward file. Briefly, smrsh limits programs to be in the directory /var/adm/sm.bin, allowing system administrators to choose the set of acceptable com- mands. It also rejects any commands with the characters: ,, <, >, |, ;, &, $, \r (RETURN), or \n (NEWLINE) on the command line to prevent end run attacks. Initial pathnames on programs are stripped, so forwarding to /usr/ucb/vacation, /home/server/mydir/bin/vacation, and vacation all actually forward to/var/adm/sm.bin/vacation. System administrators should be conservative about populating /var/adm/sm.bin. Reasonable additions are utilities such as vacation(1) and procmail. Never include any shell or shell-like program (for exam- ple, perl) in the sm.bin directory. This does not restrict the use of shell or perl scrips in the sm.bin directory (using the #! syntax); it simply disallows the execution of arbitrary programs. OPTIONS The following options are supported: -c command Where command is a valid command, executes command. FILES /var/adm/sm.bin directory for restricted programs ATTRIBUTES See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |system/core-os | +-----------------------------+-----------------------------+ SEE ALSO sendmail(1M), , attributes(5) SunOS 5.11 6 Nov 1998 smrsh(1M)
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