topic Re: ssh hang on pseudo terminal initialization in Operating System - HP-UX

ssh hang on pseudo terminal initialization

Brian Malone — Mon, 19 Mar 2007 08:57:00 GMT

Good day to all. Has anyone had any issues with OpenSSH on HP-UX B.11.11 and pseudo terminals? I have a box with 'OpenSSH_4.2p1-hpn' and 'OpenSSL 0.9.7i'. When I connect in using ssh, there is a long delay (5-20 seconds) before I actually get a pseudo terminal allocated (times depend on system activity). If I ssh from another box to run a command not using a pseudo terminal, there is no delay. I also have 2 other HP-UX servers with the same software version, but with fewer processors and less memory and I don't have the same issue on those. Any help on this is greatly appreciated. Thanks for your time.

Brian

Re: ssh hang on pseudo terminal initialization

Wouter Jagers — Mon, 19 Mar 2007 09:00:24 GMT

In my experience, such delays are usually caused by name resolution issues.

You could either make sure the server you're connecting to can resolve your client's address, or you can disable the use of dns by sshd through the config file.

Hope that helps,
Cheers,
Wout

Re: ssh hang on pseudo terminal initialization

Brian Malone — Mon, 19 Mar 2007 09:09:21 GMT

Thanks for the fast response. I'm connecting just fine with no delay. It's just after successful authentication, it takes on average 15 seconds to actually get a working shell. It doesn't seem to matter if I use PubKey authentication or password. Once successfully authenticated, it's just a delay to get a prompt. Here's some verbose output from ssh:

Re: ssh hang on pseudo terminal initialization

Wouter Jagers — Mon, 19 Mar 2007 09:16:00 GMT

Yes, that's what I usually get when resolution is not ok: login, delay, shell.

If possible, could you try placing your client's name + IP address in /etc/hosts on the server and retry ? (that's usually how I check, minimal hassle)

Cheers,
Wout

Re: ssh hang on pseudo terminal initialization

Brian Malone — Mon, 19 Mar 2007 09:27:22 GMT

Thanks. I added the IP and hostname to /etc/hosts and it's set to check hosts first then dns. I still have the same behavior.

Thanks for the help. Appreciate your time.

Re: ssh hang on pseudo terminal initialization

Wouter Jagers — Mon, 19 Mar 2007 13:11:25 GMT

myes, and sorry. thought about it on the way home, the delay I was talking about did occur between username and pass prompt.

No more 'from experience' ideas, though.. does running ssh very verbose show anything ? Or perhaps you could fire up glance on the server end meanwhile, if it seems performance related.

Sorry again about the previous :)

Cheers

Re: ssh hang on pseudo terminal initialization

Dave Hutton — Mon, 19 Mar 2007 13:16:58 GMT

Which version of hpux version? 11.00 or older?

Two things I found.
If /var/adm/wtmp is huge it can take a while. You may try to zero it out.

Also from what I read 11.00 or older doesn't come with a random number generator?
If you do a search there are some suggestions on how to fix this.

Re: ssh hang on pseudo terminal initialization

Dave Hutton — Mon, 19 Mar 2007 13:22:51 GMT

Not sure how many times I re-read your message. I see you said 11.11.

Ignore my suggestions.

Re: ssh hang on pseudo terminal initialization

Court Campbell — Mon, 19 Mar 2007 13:26:15 GMT

You can try disabling the revere lookup by uncommenting the following line in sshd_config:

#UseDNS yes

and changing it to:

UseDNS no

Then restart the ssh daemon. Hope that helps. If not then at least you have eliminated that as the problem.

Re: ssh hang on pseudo terminal initialization

Court Campbell — Mon, 19 Mar 2007 13:28:18 GMT

Also, tail -f the syslog.log file and try and connect. You should see the login attempts in that file. Maybe you'll find something interesting.

Re: ssh hang on pseudo terminal initialization

Brian Malone — Mon, 19 Mar 2007 13:30:24 GMT

Thanks for all the suggestions. Dave nailed it with the excessively large wtmp. I've put a rotate script in to copy wtmp and compress it and blank out the orig. That cleared up the slowness completely.

Thanks again, Dave!

Brian

Re: ssh hang on pseudo terminal initialization

Brian Malone — Mon, 19 Mar 2007 13:33:56 GMT