Last night the Helpline caught me on IM and let me know that the res-hall network was not exactly running smoothly. According to the reports, users plugged in in many dorms as well as via wireless were having trouble raching email, the internet, or the Gustavus home page. However the lab computers in the dorms were working well. The main thing that all of those networks that were having problems have in common is our linux based firewall that keeps nasty network traffic from spreading across campus.
So, with a bit of luck, I discovered that our res-hall firewall a.k.a Fluffy, was having a bit of trouble keeping track of all the network traffic. Most likely due to a high usage of P2P programs such as Bittorrent. Anyway one of the configuration settings was set too low for the size of our network. I ran the following command and everything started working again:
echo 440000 > /proc/sys/net/ipv4/ip_conntrack_max
We had that value set at 220,000 and apparently our res-hall firewall needs to keep track of more connections than that.
Leave a Reply