I was getting some to me inexplicable behavior from apt-get/aptitude on an admittedly crusty old webserver. While it was otherwise running fine, as soon as I tried a package upgrade, after a downloading a few updates it would stall completely, then my SSH session hung (and I was unable to reconnect), thus requiring a hard restart.

First, I switched to a different package source in /etc/apt/sources.list, but still got the same behavior. At this point I was assuming the NIC was dying in some weird way... but as soon as I changed the package source to use FTP instead of HTTP, everything worked fine, and I was able to upgrade.

For now I'm not too concerned since I have an easy work around, but it implies that there's something very weird with my network setup, since it seems to be protocol (or port?) specific. I didn't think any of my NAT setup would affect outbound traffic, but I could be crazy. Any ideas what I should try to look for?