Machine not locked-up but can't log on either

[Ryan Golhar]

Yes, I do use LDAP authentication (but the root user is a local user). 

I'm also limiting who is allow to connect through ssh via
/etc/hosts.allow.  I'm restricting it to the ISPs of our users.  I
suppose its possible someone is trying to gain access from one of those
ISPs, but the logs of the other machines only show an occassional failed
login attempt.  Would the ssh login attempts also prevent me from
logging in from the console?

Ryan

-----Original Message-----
From: Ray Van Dolson [mailto:rayvd at digitalpath.net] 
Sent: Thursday, May 04, 2006 1:07 PM
To: golharam at umdnj.edu; General Red Hat Linux discussion list
Subject: Re: Machine not locked-up but can't log on either


On Thu, May 04, 2006 at 01:02:12PM -0400, Ryan Golhar wrote:
> I have a machine configured just like 20 other machines (kickstart). 
> Every once in a while the machine just hangs.  The X terminal is dead,

> but you can toggle to the other console terminals.  After you type in 
> your name and password, it hangs.
> 
> I'm able to ssh to the machine, and type a name/password but it hangs.

> I can't even log in as root from the console - root is set up as a 
> local account in case the network goes out we can still get access to
it.
> 
> The only thing I can do is hit the power button but I'd like to find 
> out why this is happening.  Any suggestions on what I can try?

Do you have LDAP authentication enabled on this box?

I have a box behaving similarly.  It'll happen at times if one of those
remote attackers trying many different ssh login attempts continues
failing. Seems like nss_ldap eventually either eats up all the memory
(memory leak) or uses up all file descriptors.

I've purposely avoided changing the SSH port or taking other
preventative measures on this machine as I wanted to try and track down
the problem. Just haven't had time yet. :)

Ray