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smrsh(1M) 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 program 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: ,, <, >, |, ;, &, $, (<RETURN>), or (<NEWLINE>) on the command line to pre- vent end run attacks. Initial pathnames on programs are stripped, so forwarding to /usr/ucb/vacation, /usr/bin/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 example, 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 |SUNWcsr, SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
sendmail(1M), , attributes(5) SunOS 5.10 6 Nov 1998 smrsh(1M)