Network Troubleshooting

Last Wednesday we had a major network issue. The story started from end-users calling our help-desk and soon there was a chaos in the department because of the increasing number of phone calls. Soon users spread the news among themselves and we confirmed the whole site is experiencing networking issues.

We spent almost 5 hours sorting out the problem, however I will only mention the steps anyone should be taking in this scenario to cut the long story short.

1. First thing first always check whether you can connect to the core switches on the site. In our case we had 2 core switches and one went down because of a faulty port on the switch (in our case it was F11). It does sound very easy however it was a nightmare for us to get to this information because we couldn't even login to the switch. We had to connect and log-in to the other core switch and find the faulty port from there.

2. Second thing to look for is the DNS. Reboot your DNS server and it fixes the problem 5 out of 10 times.

Admin changes

Last week, during our Infrastructure IT Audit, we decided that we need to change the local admin accounts on all the pc's on the company's domain. I looked around for the simplest way to achieve this. There are many forums explaining the procedure, therefore I thought of summing it all up and put it all in one simple way.

There are couple of ways we can perform this operation: -

1. WUS.

2. By installing GP CSE (client side extension) and XML Lite on every pc.

3. WMI scripts OR

4. Using the pspasswd command from pstools.

Out of the all above the best is the WUS way. However, we do not yet have this implemented therefore the second option was to install the CSE and XML Lite for running a centralised script on the network. This seems a good choice however this also needs visiting all the pc’s. The GP Client Policy is coming as an update from MS now, so you could install this patch next time on the pc visit?

OR

The simplest way to do the above is using the pstools. I have tested it now and it is working quite well without the users realising and it also uses Windows password reset APIs, so does not send passwords over the network in the clear.

This could also be done in batch for more than one or all computers through file list.

Here is what you need to script (make sure you are logged in as an admin on network) : -

usage: pspasswd [[\\computer[,computer[,..] | @file [-u user [-p psswd]]] Username [NewPassword]

Therefore go to the command prompt (I personally use Powershell on PC's) and type the following (if you are changing the local admin password for one PC): -

cd PsTools

.\pspasswd.exe \\computername localadminusername localadminnewpassword

Aaabra ka Daabra, thats done for you. You will be displayed with the following msg: -

Sysinternals - www.sysinternals.com

Password for computername\localadminusername successfulyl changed.