Search code examples
network-programmingsmb

SMB - Server never responds to Session Setup Request

I am having very strange network problems. I am on a domain where a few servers are located on a different subnet. I can ping these servers, dns look them up and remote desktop to them by IP-address. I however cannot find them when using:

net view \server or Try to access them via windows explorer.

The person next to me who has an identical machine and is on the same subnet has no problems, as a matter of fact, I am the only one in a 50 person company having this problem!

This wouldn't be so much of a problem except for the fact that my machine cannot use web services located on these servers, neither via HTTP or NET.TCP.

After trying everything I can find on the internet and some more (added a new network card, reset policies, etc.) I finally got WireShark to see what is going on. When doing net view \server I notice that the server never responds to "Session Setup Request" but it did respond to "Negotiate Protocol Request". So what could possibly cause the server never to responde to the Session Setup Request?

WireShark Capture

Here is the server side capture (Not same session)

enter image description here

Solution

  • OK I found out what this was by comparing my tcpip registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters) with a machine that worked. What I noticed is that I had the following 2 entries

    EnablePMTUBHDetect  0
EnablePMTUDiscovery 1

    but the other machine didn't. By deleting these entries, everything started working!

    This however is very strange because these happen to be the default values for there registry keys so I do not understand why having these entries cause such a problem.