This is by far the weirdest problem I've experienced. I have a FC 2 machine that lives in a network behind a firewall (router runs some form of linux). My machine and the rest in the network all have publicly accessible IP addresses and all machines can be pinged. We took the necessary steps to open traffic in the router to my machine.
Now for the weird part. The machine refuses connections to ANY service from the internet until a connection is first made from within the network. At first I thought it was because I had 2 nics in the box and only one was opened through the firewall so I disabled the second interface entirely.A friend of mine VPNs into the network and ssh's into the box, once he connects then I can access the webserver on the box, ssh in, whatever else i want. After several hours it reverts to refusing connections until the process is repeated.
Anyone have any creative ideas on this? I read somewhere about ECN and I disabled that. I have iptables disabled and I'm all out of ideas.