Thursday 26 August 2010

Problems connecting to Remote Desktop over a VPN

Troubleshooting issues with Remote Desktop connections

By Strictly-Software

I have just experienced and finally resolved a problem that started suddenly last week that prevented me from connecting to my work PC from my laptop at home using Terminal Services / Remote Desktop.

The problem started suddenly and it has made little sense for the last week. The symptoms were:
  • A virgin media broadband Internet connection.
  • A windows XP laptop connected to my broadband over a wireless connection.
  • My laptop could access the VPN without any problem and it could also access the PC in question over a windows share e.g \\mycomputer\c$
  • Trying to connect using a Remote Desktop connection returned a "this computer cannot connect to the remote computer" error message.

As far as I was aware nothing had changed on my computer and I first though that maybe a virus was blocking the port or a windows update had caused a problem. However when I brought the laptop into my office and tried connecting to my PC over the office wireless connection there was no problem.

I then tried this great little tool RD Enable XP that allows you to set up remote desktop access remotely as long as you have access to the computer and the necessary admin privileges. It requires that you have PSExec installed which comes with the PSTools admin suite and allows you to carry out tasks on computers remotely such as monitoring and managing processes.

The program checks that you can access the remote PC, that the Terminal Services options are enabled correctly in the registry and that you're not being blocked by a firewall.

I had already checked that the fDenyTSConnections registry option was set correctly so when the application hung whilst trying to set firewall exceptions I thought that there was a problem with my router and firewall.

I then tried changing the port number that Terminal Service connections are carried out with from 3389 to 3390. This is another registry setting that needs to be changed on the remote computer and then after a reboot you just append the port number after the computer name or IP address when connecting e.g strmycomputer:3390.

This didn't work so I was pretty annoyed as Virgin media hadn't been much help so I was about to give up until I came across a message thread related to the same problem.

One of the suggestions was to change the Advanced Network Error Search option which is something Virgin offers it's users and is described as follows:

Our advanced network error search helps you find the website you're looking for quickly.

We all make mistakes when we type in website addresses. Perhaps we miss a few letters, or the website doesn't exist any longer. If an address you enter doesn't locate a site, this handy feature will convert the incorrect address into a web search, so instead of an error message you will get a list of our closest matches, plus some additional related links.
This option is linked to your broadband connection which explains why the problem was related to the local connection and not the PC or remote network.

Low and behold when I disabled this option I could once again access my work PC over Remote Desktop again!

I have no idea why this option was suddenly enabled as I have never come across or even heard of it before tonight so I can only imagine Virgin decided to update their settings without asking their customers first.

It also seems to be pre-selected on newly bought laptops as I found out again tonight! Lucky I wrote this blog article otherwise I would have had to hunt down the original again!

I have no idea why this Virgin config option affects remote desktop connections but it obviously can cause a total block on this type of functionality.

If you too have similar problems related to Remote Desktop connections and are also a Virgin Media customer then save yourself a whole lot of time and go to this page first and check your settings:

Friday 6 August 2010

Techies Law - Definition

The definition of Techies Law

In a similar vein to "Murphys Law" which states if something can go wrong it will I have over the last two days experienced multiple occurrences of what I call "Techies Law" which all developers should be well aware of even if they haven't heard the term described as such.

The law is pretty simple and states that
If you have spent considerable time trying to resolve a bug in your code, technical problem or other such computer related issue and you finally resort to asking for help from a colleague or support team member. You can be rest assured that when you go to show said person the problem in action it has miraculously resolved itself. You are then derided for either being a numpty and/or wasting their precious time for no reason.
Obviously Techies Law often leaves developers looking foolish in front of their colleagues but I have decided to utilise this unfathomable law of nature to my own benefit.

Every time I now have a problem with my network connection or a bug in my code I need fixing instead of spending a long time trying to fix it myself I will now only spend a quarter of the usual amount of time I do before asking for help and in doing so I usually find the issue magically resolving itself.

The knack to this tactic is to make sure the person you ask for help is not someone who is able to rip the piss out of you and is someone who won't mind being pestered for such a reason otherwise you could find yourself being the subject of many jokes.