Michael Rash, the author behind "Linux Firewalls" chimes in about his background, his distro of choice, the current state of Linux security and much, much more.
He covers many issues and provides a lot of insight into security and Linux:
Question: What is the most interesting fact you've become aware of while researching for this book?
Intrusion detection systems and firewalls commonly offer the ability to tear down TCP connections by forging a RST packets, but the specifics of how this is done varies quite a bit across different IDS and firewall implementations. The most interesting fact I stumbled across during my research concerns differences in the handling of the ACK control bit on RST packets. For example,
IPFire is a linux based firewall distribution with a lot of extras. The base for the stable version 1.4.9 was the IPCop that has been hardly modified. There were added: Asterisk PBX, Samba, MorningReconnect, LPR-NG and many other things.
I've always been a fan of Shorewall and Firestarter - what have you used as a good base firewall setup? Any thoughts how this will match up in an enterprise server environment?
Firewalls are often framed as a one job tool. Furthermore, when looking to set up a secure network infrastructure, this Debian Admin says that sometimes they aren't aren't even needed!
To the contrary, Firewalls can be engineered to serve a number of purposes such as fragment reassembly for instance (as the author at TuxMachines states) and are generally only as secure as they are configured to be.
It seems that Firewalls are commonly misconceived of both being the given for network security (possibly not true) and not nearly enough on their own (the given among those who know security).
(bonus points for those who know the movie being alluded to in the title)
Sometimes a rule configuration may reside in a place other than the basic rule configuration place. In such a case, it is difficult to confirm whether it is an intended configuration by the system administrators. (Is an unnecessary hole open, or is a necessary hole open?) So, we developed a tool which checks the rule of a Firewall.
In any network your first line of defense is the firewall. One new firewall checker is called Dr.Morena. It's made up of two modules one is the check engine and the other is the packet list making engine. They work on Linux so it's good at checking your iptables. Go ahead and test your firewall to see how well it protects your network.