Linux Productivity Magazine - Volume 2 Issue 4 & Issue 5 [LWN.net]

Two issues of Linux Productivity Magazine are available, with a detailed look at securing your system. The April issue focuses on Tripwire. "Tripwire is an Open Source program created to monitor changes in a key subset of files identified by you, and report on any changes in any of those files. When changes are detected, you, as the sysadmin, can determine whether those changes occurred due to normal, permitted activity, or whether they where caused by a breakin. If the former, you can update the system baseline to the new files. If the latter, you can shut down and begin repair and forensic activities."

The May issue is devoted to IPTables. "IPTables is a firewall program. It can restrict access by port, by IP address, or by the properties of packets. Firewalls aren't everything you need for security, but they're an excellent first step."