Limiting Network Risks
Although it might seem like there is nothing you can do to protect your machine, there are certain measures you can take to limit network risks. We will look at limiting per-service access with TCP Wrappers and using the built-in firewall, ipfw.
Limiting Per-Service Access with TCP Wrappers
A common way to restrict access to some TCP services is to use the TCP Wrappers program. TCP Wrappers is a package that monitors and filters requests for TCP (Transmission Control Protocol) services. We don't look at the protocol in any detail here—that's a book subject in itself. Suffice it to say that the protocol has enough control information in it that we can use a package like TCP Wrappers to filter some of that traffic. TCP Wrappers ...