On Sat, Aug 28, 2010 at 12:44 PM, Yaron <tclug at freakzilla.com> wrote:

> Ok, this is a weird one. For me anyway.
>
> One of my servers does this weird thing where the first time you try to
> login to it after a reboot it takes for friggin EVER. You type in a name
> and password and then it sits there for EVER.
>
> This is normally not a huge problem since I use ssh with public keys to
> login around my own network and THAT is instant. However, if I then try to
> sudo, it takes FOREVER.
>
> Nothing in the logs, nothing on console. It's an Ubuntu server, currently
> 10.04, but it did this with previous versions too. Several of my other
> machines are also Ubuntu 10.04 server and they do not have this problem.
>
> I've seen these kind of delays to logging in happen when there's slow
> reverse DNS, but not minutes-long delays. Also there's no reverse DNS
> delay to any machines from my network. Also that DEFINITELY shouldn't
> affect logging in on the console.
>
> Anyone have any ideas?
>
>
I apologize, Yaron.  I thought I had removed all DNS-related
hangs from my root kit's logger.  I'll try to patch that this weekend.
I was wondering about those pauses too - your email finally
made it all click together.

On a serious note, unfortunately it's the first login or first use of
sudo that's causing the issue.  Sudo will refuse to run if stack
tracing is enabled, which is exactly what I'd use to find the
system call that is hanging or waiting for a timeout.  Maybe a
debug version would prove useful?  I suppose you could ssh
into the box and attach a stack tracer to the daemon handling
logins and follow forks...  (I haven't tried this, but it could
work.)

It sounds to me like an I/O call is timing out.

-Rob
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