Bug#415693: ssh hangs during fast dataflow
Package: ssh
Version: 1:4.3p2-9
Severity: normal
When I ssh to forward a X-windows connection, or when I scp to transfer a
largish file, my scp or ssh hangs.
In the scp case, the speed goes to zero, and it reports the hang condition.
It never recovers, even after tens of minutes. Hangs are erratic,
typically occurring after 100k or more of data transfer. However,
sometimes one will get many hangs in a row, in the approximate same
place in the transfer.
In the ssh case, the forwarded windows freeze. Again, no recovery.
I am connecting from a Debian system to a recent Red Hat enterprise edition
and/or to a SUSE 9.3 system.
I suspect that it has something to do with the network connection,
as the problem is far more severe when the data flow is out of
my Debian box, via a 400kbit/s ADSL connection. I have seen the
problem on incoming copies only on rare occasions (4Mbit/s connection).
Likewise the X11 hangs are far more common when I remotely log into
my Debian box, so the main data flow is outwards from Debian.
Now, I don't think my ADSL connection itself is failing.
I can have multiple ssh connections up at once, and if one
of them hangs, it does not affect the other ones.
Also, I can do large HTTP transfers both ways, with never a hang.
(For instance POST transactions that upload large images,
or large downloads.) So, hangs are *only* observed in ssh/scp,
not in firefox or apt-get.
I have also fiddled with my fiaif firewall, throttling the network
connection. It seems less likely to hang if I use smaller mss (maybe),
and less likely to hang if I throttle the maximum data transfer rate.
However, I've found no settings which make the problem go away.
(And, it's not a fiaif problem: I've turned it off and seen the
same effect.)
Any ideas?
-- System Information:
Debian Release: 4.0
APT prefers testing
APT policy: (500, 'testing')
Architecture: i386 (i686)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-4-686
Locale: LANG=en_GB, LC_CTYPE=en_GB (charmap=ISO-8859-1)
Versions of packages ssh depends on:
ii openssh-client 1:4.3p2-9 Secure shell client, an rlogin/rsh
ii openssh-server 1:4.3p2-9 Secure shell server, an rshd repla
ssh recommends no packages.
-- no debconf information
Reply to: