Case of an FQDN Issue

The phrase, "I can't access my shared drive" was intermittent, but becoming common for a remote location connected via an MPLS circuit. Without hesitation the finger was pointed at the network and my phone rang. People connect to shared drives everyday, but it is one of those things they take for granted. Behind the scenes there are many layers of technology, protocols, and devices working together to make those connections happen. I can’t count the number of ways to hinder performance of a network share or prevent it from working altogether. *SPOILER* If you’re like me and you like to know the big picture first, the problem in this case was DNS. Read on for the details, or just know a great test is to place a ‘.’ at the end of your DNS path. To kick things off I asked for a screen shot of the error. This is what I received: Obviously, this was not very helpful (are error messages ever?)....
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Case Study: Capture at Both Ends

While the general rule of thumb is to capture at the client, or at least start there, sometimes it's necessary to take captures at both ends of a connection. The client perspective will allow you to view the problem as it is seen from the client. The server perspective might show the same thing. Or, in some cases like this one, it will provide the reason for the problem. The problem was that a webpage wouldn't load. There were various errors and no real indication of the problem. While SSL was suspected, there was no proof. So, we started with a capture at the client. From the client, the capture reveals it sent a TLSv1.2 Client Hello as expected. However, it then abruptly ends with a FIN with no server hello. Versions and ciphers were compared in the settings, but everything matched. More data was required. Another capture point was setup on the server. Immediately, the problem was revealed. The server received a...
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