I am having an issue where one host on my network cannot FTP or ping external sites but the rest can. My setup is with a single router with wireless and ethernet. With my host on the wireless I can FTP and ping fine but with my host on ethernet I can't ping or FTP external sites.
What makes this a bit strange to me is that I can wget from the ethernet host fine and it is resolving names correctly. Also I CAN ping the internet gateway immediately beyond my router so it doesn't seem like it's the routers doing. At this stage I'm at a bit of a loss as to how to diagnose the problem further.
Both hosts described are linux. The ethernet host that can't connect is a server with no GUI and it is the only wired host so I can't wireshark capture what is going on. Also router has no firewall enabled.
Anyone have any ideas as to what could be happening here?
This sounds, as if it might be related to MTU issues! http://en.wikipedia.org/wiki/Maximum_transmission_unit
Well this turns out to be a pretty lame solution, but turning the host in question off and on again has fixed the problem. I am still a bit bamboozled as to how it got into a bad state or what exactly was wrong.
I have opened another question here asking about the output of tracert for the machine in question if anyone is interested.
EDIT:
Turns out that I had peerguardian for linux running on the machine and it was assassinating all incoming packets :P