We’re having problems with one of our HPUX boxes dropping users at random for no reason. The person that administers the HPUX system has turned up additional monitoring, but hasn’t found anything. The situation shows itself as one or more users getting disconnected from the HPUX system when using SSH as the client method to attach (which is the only thing we allow). What else can we look at to help find the problem?
– Via the Internet
SSH can be a little tough on connection issues sometimes, so there are several things to look at. Keep in mind that the solution to this type of problem may require changes in more than one area. Have your HPUX admin verify that the latest patches are applied and the newest network card driver is installed on the system. See if there are any updates to the SSH service on the HPUX box that should be installed to help eliminate that as the problem.
Look at your network switches to see if you can turn syslog functionality on them and set up a system using something like Kiwi Syslog to allow you to see the messages at a central location. Look for any errors on the ports on which the SSH/HPUX traffic will be going through. If no errors are being reported via syslog, look at the port configuration of all switches that are connecting the HPUX box to the network to where it comes back into the core of your network. If the ports are set to auto detect on speed and/or duplex, hard code those settings to where they are all the same (e.g., 100 MB full duplex). I have seen problems where a mismatch in just duplex can cause problems.
Another area to look at is the SSH client. You didn’t mention the vendor or version of the client you have in your message, but upgrading to the latest version could help. You can also try a SSH client from another source. Make sure that the client workstations having this problem have the latest network card drivers installed. See if you can find out what has changed recently on the network to help detect where the problem might be.
