ssh/sshd hang after "debug2: channel 0: open confirm rwindow 0 rmax 32768"

[Bruce Allen]

Dear openssh developers,

Sorry to bother you with this, but I am stumped!

ssh client version:
OpenSSH_3.9p1 NCSA_GSSAPI_3.5 GSI, OpenSSL 0.9.7d 17 Mar 2004

sshd server version:
OpenSSH_4.6p1-hpn12v17 NCSA_GSSAPI_GPT_4.0 GSI, OpenSSL 0.9.7d 17 Mar 2004

The client/server interaction hangs just at the very end, after 
authentication is complete.  Here are a few lines of ssh -v -v -v output:

------------------------------------------------------------
...
debug3: tty_make_modes: 90 1
debug3: tty_make_modes: 91 1
debug3: tty_make_modes: 92 0
debug3: tty_make_modes: 93 0
debug2: channel 0: request shell confirm 0
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768

[HANGS HERE FOR A COUPLE OF MINUTES! Then after an agonizing wait...]

debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
   #0 client-session (t4 r0 i0/0 o0/0 fd 5/7 cfd -1)

debug3: channel 0: close_fds r 5 w 7 e 8 c -1
Read from remote host XXX.XXX.uwm.edu: Operation timed out
------------------------------------------------------------


This bug has appeared on a stable set of systems that have worked well for 
quite some time. The only thing that has changed is that I am in a hotel 
room with some new ISP (in a few hours I'll try from a different 
location). We have a number of hosts set up the same way, and I can not 
log into any of them, so it's probably not machine misconfiguration on the 
server side.  And the client works fine with a different set of hosts! 
So it's probably not machine misconfiguration on the client side either.

Only thing I have checked is that I've dropped my MTU to 576 thinking that 
there might be some packet fragmentation issues with the hotel's NAT box 
but that didn't help.

PS: Thanks for openssh.  We wouldn't be able to work without it!

Cheers,
 	Bruce Allen