I am using skype 1.4.0.99 on Ubuntu Fiesty and Gentoo. I have an iptables firewall (shorewall) that allows any outbound traffic and only ssh and https for inbound.
I don't know very much about analyzing network traffic. Using ntop, I notice under 'Host Contacts' for my machine in just one day of using skype is 60,000. When I don't run skype, it is around 500. There is also a lot more UDP traffic. I've looked at it with tcpdump. It occurs in bursts where I receive 4 UDP packets from about 100 hosts at one time. Is this how 1 phone conversation is transmitted? Does this mean I am a supernode?
We are already not allowed to use Skype in our lab (all machines behind a firewall) because of the network problems it causes (and my administrator is fairly lax). I suspect we will also be told not to use it in my dorm pretty soon after speaking to the network administrator. Something about it filling up the host table on the router.
Is there any way to restrict it's behavior through some iptables settings so it doesn't cause these problems?