My iptables are set up exactly as that site recommended (excluding the ssh bit). That is:
# rc.firewall for
# Basic Slackware Security
# These two rules set the default policies, i.e. what to do if a
# packet doesn't match any other rule, to drop any packet coming
# into (INPUT) or routing through (FORWARD) the box.
iptables -P INPUT DROP
iptables -P FORWARD DROP
# These rules are added (-A) to the INPUT chain. They allow packets
# from any previously established connections and accept anything
# from the loopback interface.
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -s 127.0.0.1 -d 127.0.0.1 -i lo -j ACCEPT
I really don't know much at this point about security/ports/firewall/iptables, especially as related to Linux. However, it sounds like a good idea to start with everything denied and slowly open things up as I need them. My question is, after following the advice given by the site above, how can I now allow AIM direct connections, and will doing that open up anything else that I don't want to be open?