Re: Putty/OpenSSH on Windows - Crash Port Forwarding

From: Jacob Nevins (jacobn_at_chiark.greenend.org.uk)
Date: 12/22/04 

Date: 22 Dec 2004 13:32:03 +0000 (GMT)

Your post is a bit thin on detail -- useful would be the version of
PuTTY, the direction of the tunnel (I'm assuming local-to-remote), and
the exact text of the "world famous time out message", for starters.

Didier Wenger <didier.wenger@lodh.com> writes:
>I've got a Windows OpenSSH server behind a NAT DSL router and I'd like to
>use Putty's port forwarding feature on an XP client trough the Internet to
>reach a mail server that sits behind the NAT. The SSH connection is OK, the
>port forwarding is working fine as I can telnet to the desired port (POP3)
>but I can't retrieve my mails because the connection always crashes. Even
>when I try to FTP to a server behind the NAT, I can successfully login but
>then when I try to list a directory, the FTP connection freezes and a couple
>of minutes later I receive the world famous time out message

Note that tunnelling FTP is difficult because it opens multiple
connections. PuTTY has no special support for tunnelling it; you might
be able to point a SOCKSified FTP client in passive mode at PuTTY's
dynamic SOCKS tunnelling (haven't tried it), but normal port forwarding
certainly won't do the right thing.

>Putty is then in a strange state and I can't exit the terminal Window,
>I have to kill it.

How exactly are you trying to "exit" the terminal window? What happens
when you try?

Are other aspects of PuTTY's UI (e.g., the Event Log) still accessible
(i.e., is it still running)? If so, PuTTY hasn't crashed; in this case,
does the Event Log tell us anything useful?

Note that PuTTY won't close the session if it thinks there are still
tunnelled connections open.

There is a known crash in remote-to-local port forwarding in PuTTY
0.56, which is fixed in the development snapshots, but this seems
unlikely to be what you're running into.
<http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/ssh-remote-tunnel-crash.html>

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