ssh client hang for prolonged connections
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| openssh (Ubuntu) |
Expired
|
Undecided
|
Unassigned | ||
Bug Description
I'm not sure if this is actually an ssh bug or if it is a bug elsewhere that only appears when I use ssh. Some suggestions for diagnosing the problem would be helpful.
ssh client connections initiated from my laptop to almost every serve I connect to will hang after 30-60 minutes. This includes both interactive sessions and scp of large files. I attached a debugger to a hung instance of the ssh client and it appears to be stuck in a syscall:
0x00399422 in __kernel_vsyscall ()
(gdb) where
#0 0x00399422 in __kernel_vsyscall ()
#1 0x0078c93d in ___newselect_
at ../sysdeps/
#2 0x00ef07ab in ?? ()
#3 0x00ef2d6d in ?? ()
#4 0x00eebd40 in main ()
ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: ssh (not installed)
ProcVersionSign
Uname: Linux 2.6.32-24-generic i686
Architecture: i386
Date: Thu Aug 26 13:38:00 2010
ProcEnviron:
PATH=(custom, user)
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: openssh
| Clint Byrum (clint-fewbar) wrote | #1 |
| Changed in openssh (Ubuntu): | |
| status: | New → Incomplete |
| Launchpad Janitor (janitor) wrote | #2 |
| Changed in openssh (Ubuntu): | |
| status: | Incomplete → Expired |
Hi Jason, thanks for filing this bug report and working with us to make Ubuntu better!
The syscall appears to be "select()", which means that ssh is waiting for data from the other side of some connection. This could be from the DNS server or the server you have connected to.
What might be more interesting is the output of the debugging mode of ssh. However, this may not be suitable for public consumption as it could contain details about the security of not only your local machine, but that of the remote machine.
If you are going to post that, you should either edit the file to remove portions that reveal the hostnames/
To generate the debugging output, simply add
-vvv
To your ssh command line, and you will get a ton of output that looks something like this:
debug1: Requesting <email address hidden>
debug1: Entering interactive session.
debug2: callback start
debug2: client_
debug2: channel 0: request pty-req confirm 1
When you post the output, Note the sections that take longer than you would expect them to (and, if you can, exactly how long).
Marking Incomplete pending Jason's response.