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I ran across an issue with ssh after fresh Ubuntu 13.10 installation on Lenovo T420. I tried git pull (which failed) and this led me to more general ssh failing.

After spending some 2-3 hrs of beautiful Sunday morning I have established:

  1. ssh is able to authenticate. see the log below. Also telnet google.com 80 hangs on connecting.
  2. I can connect using putty - it shows motd and prompt
  3. It doesn't work on both wired and wireless connections, also I tried cellular network.
  4. I can successfully login to localhost

here be the log:

debug1: Authentication succeeded (keyboard-interactive).
Authenticated to web1.mydevil.net (via proxy).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LC_PAPER = pl_PL.UTF-8

and then just keeps sending

debug1: client_input_channel_req: channel 0 rtype keepalive@openssh.com reply 1

without showing me the prompt and eventually disconnects.

I found out that telnet google.com 80 hangs on Connecting <IP-addr>... as well.

share|improve this question
Have you checked /var/log/auth.log on the server for possible error messages? – Martin von Wittich Jan 27 '14 at 19:47
Permission denied. as expected. this is not my machine. – Maciej Jankowski Jan 27 '14 at 21:49
Hmm... is it possible that the server is somehow misconfigured? I'm not really sure how to debug this further. You could check the output of ssh -vvv if there's anything more interesting in the debug messages, but the client side log was rarely helpful for me when debugging issues like these. – Martin von Wittich Jan 27 '14 at 22:35

Okay, this on turned out to be WTF LOL squared...

I got a hint that it was most likely ICMP packets being filtered by the firewall. So when you stumble upon this issue check it out.

In the article I found on Hacker News one reads:

ssh did not work. It would connect, flip some data back and forth (as shown with -v) and then would hang.

Certain websites would become inaccessible.

Which were my symptomps that appeared after switching my wireless router to another device. Device in question was Linksys WRT-54G running dd-wrt.

share|improve this answer
"Filter all ICMP and watch the world burn", indeed. I take it DD-WRT was the failing device, right? – sourcejedi Feb 2 at 15:09
yup, that seemed to be the problem. Maybe I messed something with its configuration. It worked on another device running dd-wrt. – Maciej Jankowski Feb 2 at 15:19

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