AIX

Server, running AIX 6.1 developed strange problem when logging in via SSH -- ssh client hangs without any error.
It is possible to run commands on server, using ssh ("ssh servername ls -l" is OK)
It is possible to log in normally, using serial console connected to server.
It was possible to access server, using pconsole web interface but it does not work any longer (Error 500: com.ibm.ws.portletcontainer.pcinvoker.PortletContainerAccess)

I noticed, that "getty" process is not running, maybe this is somehow related to this problem.

Any ideas or suggestions where to start digging, considering that server itself is located in another city?

A typical problem is a removed access to the random-device. This is how it comes to this:

Some security-idiots without any semblance of UNIX-knowhow prescribe a UMASK of 277 (instead of the system default of 022). This causes new files, directories, etc. to be created without any access for users per default (which is a "great" idea in itself, because root is supposed not to work for the users anyway, is he?). If such a root-account now touches /dev/random somehow no user can use it any more and ssh (that is: the underlying OpenSSL-library) will hang, because this exception is not foreseen and hence not taken care of.

I have seen this sort of idiocy with the UMASK now at least 3 times in different places so i presume there is some "security"-primer out written by some malevolent computer-hater with a hidden agenda to render all UNIX-systems useless.

I hope this helps.

bakunin

Thanks for interesting suggestion. Unfortunately this seems not to be cause of my problems:
ls -l /dev | grep random
crw-r--r-- 1 root system 37, 0 Apr 09 10:14 random

Ssh sort of works -- i can run commands remotely, but i can not get interactive shell. Maybe it is somehow related to pseudo-terminal devices?