This document describes how to solve the Sendmail server security problem-Linux Enterprise Application-Linux server application. Sendmail is the most widely used email sending/receiving proxy in Unix environments. Because the Sendmail mail server is powerful and complex, the following work is required to ensure the security of Sendmail.
1. Set Sendmail to use "smrsh"
The smrsh program is used as an alternative shell for "/bin/sh" defined for sendmail in mailer. Smrsh is a restricted shell tool that explicitly specifies the list of executable files through the "/etc/smrsh" directory. In short, smrsh limits the Assembly that attackers can execute. When it is used with the sendmail program, smrsh effectively limits the range of programs that sendmail can execute to the smrsh directory.
Step 1:
Determines the list of commands that smrsh can allow sendmail to run. By default, the following commands should be included, but not limited:
CODE: "/bin/mail" (if it is installed in your system)
"/Usr/bin/procmail" (if installed in your system) |
