Ive recently switched over to AT&T Uverse TV/Internet service and I've noticed that when I ssh into my linux( 2.6.18-194.3.1.el5xen CentOS) server I get disconnected. When I'm using putty it gives the "network error software caused connection abort" error. When I'm at work using one of our jump servers and ssh'ing from the command line it will freeze up from time to time but never disconnects. I think the problem is either with the OS or the new AT&T modem. At first I had my CentOS server using DHCP and it would disconnect within a few minutes after I ssh'ed. I switched over to a static IP and now it goes about 10 minutes before it disconnects. It doesnt matter if I'm actively typing or not, so it's not an inactivity issue. I have the firewall turned off on my laptop, and since the issue happens on multiple devices, including my iphone I dont think thats the issue. I have iptables and selinux turned off/disabled so thats not it. In putty I have enabled Keep Alive(30 seconds) and it still disconnects. I opened the port on the modem to allow ssh for the IP of the linux server.

Ive also recently reinstalled this server with CentOS so I can't compare with the previous internet provider as I didn't reinstall until after I switched over. BUT previous installs with CentOS 5.2 worked fine with the previous ISP.


AT&T Modem is a 2wire 3800HGV-B

Ive search all over the place and cant seem to fix the issue. Any other ideas?

can you ssh locally through your home network? It may be an issue with your ISP not allowing the traffic... trying to log in through your lan will tell you if it's your server or not.

A further means to debug this would be to start a tcpdump on the home-server, writing the output to a file. You can then examine the file with etherreal (or whatever it's called these days).

^^ it disconnects if I try the local IP or the public IP or hostname.

^ hmm hadn't thought of that. I'll give it a try. Thanks.

Whoa! Routers, ISPs are of course the most likely culprits of this problem, but it seems you have something local. Check the kernel log (type dmesg, or look in the /var/log/kern.log file) if there are any hints there.

I had kind of forgotten about this because I've had other projects and hadn't needed to SSH into my server. So I SSH'ed in last night, same as before and it worked. So for shits and giggles I left the session connected overnight. When I woke up this morning the session was still open. Who knows. But for some weird reason it works. Thanks for the replies.