UFW (Uncomplicated Firewall) is the default firewall (iptables) configuration tool for Ubuntu and while it's a great tool, it might scare those not very familiar with the command line.
Vuurmuur is graphical front end for famous firewall software iptables. You can make complex firewall rules in simple steps. Vuurmuur supports traffic shaping, has powerful monitoring features, which allow the administrator to look at the logs, connections and bandwidth usage in real-time.
Everybody, who tried to configure an iptables firewall knows, that it can be quite a PITA. firehol is a tool that helps us to configure iptables according to our needs. In this How-To, I will discribe how to set up an iptables firewal using firehol that only allows SSH and ICMP (the protocol responsible for ping and traceroute). Also, only incoming connections are filtered, and outgoing connections are allowed.
In some countries, or better said some ISP have started to block port 25 to avoid PC viruses to send copies of themselves by email to all the contacts on you address book.