I've used Ubuntu since more than a year now, as the Oneiric Ocelot has more than exceeded my expectations and provides most things out of the box. However, there is one feature that both Windows and Fedora provides - a network firewall that allows us to block specific incoming/outgoing ports such as HTTP(80), FTP(21), etc. I've seen it on Fedora17.
Since I'm going to learn some network programming, such a firewall will be very much useful for my development and testing.
Is there any such equivalent (and reliable) package in Ubuntu repository? I'm aware that I cannot fetch anything from the Fedora repo as they are in RPM formats, and also don't want to mess something with my Ubuntu deb packaging.
ufw(see Rinzwind's answer),
gufw(the gui version of UFW, needs GNOME runtime libs), or direct
iptablescommands are good ones.
firestarteris deprecated nowadays since it requires admin privileges to run, regardless of user, so that is dangerous.