I have two desktops and a laptop running Arch Linux. I have not setup any iptable rules on any of the machines, and I am curious if I should.
One desktop is only used in my home network and is "protected" by a cheap cable modem/router/firewall that is essentially unconfigured and unmaintained (I changed the default password when I got it and haven't looked at it since in 3 years). The desktop runs standard home user applications (e.g., web browsing and Skype) as well as an SSH server. As far as I can tell the firewall default configuration blocks all incoming connections since I can only connect to the SSH server from within my home network.
The other desktop is behind my University's firewall. It is more permissive (I can SSH into the machine from off campus) and hopefully better maintained. Apart from the SSH server the machine doesn't do anything network related other than web browsing and Skype.
The laptop is used behind the home firewall, the University firewall and sometime on unsecured public wireless and wired networks (e.g., hotels and coffee shops).
Is it worth configuring IP tables and if so should the configuration vary across the machines? Potentially related, is it worth setting up a separate independent firewall to protect my home network?