Can't connect using Remote Desktop after changing default port in registry/router.

Can't connect using Remote Desktop after changing default port in registry/router.

I played around with RDC for the first time this weekend, and it seemed to be working fine before I changed the default RDC port (3329 or something?) in Windows and on my router. I used my wife's computer to connect to my computer remotely, and it worked whether I typed in the computer name or the IP address. However, I found some instructions on the web for changing the default RDC port in Windows to make my computer more secure against unauthorized connections. I followed the instructions word-for-word, which basically just involved changing the Windows registry default value for the RDC communications port, and applying the changes to my Linksys router (in the "Applications and Gaming" tab, I opened up the same port number that I used in the Windows registry). After I made this change, I could no longer connect remotely no matter what I typed in for computer name. My understanding is that I should be able to connect by entering the IP address and the port number preceded by a colon, e.g. 111.111.1.111:11111.

Any ideas what my problem could be? Thanks.

Hrm, perhaps you should just restore your backup of the registry. It can be a tricky and sticky mess with the registry.

You could use nmap to see if the computer is even responding on that port. If you install nmap just do a "nmap -sT 111.111.1.111" and see what port RDP is repsponding to.

If you really broke RDP you could also go and use Ultr@VNC. It might not be quite as responsive as RDP but it has a heck of a lot more features and it was way better as it has a built in FTP client/server.

But tell us how it goes with the nmap 1st.

I installed nmap and ran at the command line like you suggested, and it didn't list any open ports for the RDP service. I tried changing the registry value back to the default port (3389), but it didn't help. I'm a bit confused: If I have a port open on the router, regardless of what it's for, shouldn't it show up as an open port on this nmap listing? Or is this testing the communication between the router and my computer?

UPDATE: Okay, I'm an idiot. I was unaware that there are separate internal and external IP addresses. All this time I have been trying to connect by using the internal IP address. This actually worked within my home network before I messed with the listening port settings, but maybe it explains why it stopped working once the listening port was changed. I will try connecting using my external IP followed by the RDP port number on Thursday when I get some time.

One more question: How can I find my external IP address?

Success! When I tried to connect using my external IP address, I was still having a problem. It turned out to be Windows Firewall, which was blocking the new RDP port number even though it had been changed in the registry. The Remote Desktop port listed in the "Exceptions" tab of Windows Firewall needed to be manually changed to the new value. Thanks for your help.

Okay, sorry for the triple post, but I have a new problem. I cannot connect to my home computer from my work computer. However, my brother was able to connect to my computer from his home computer. I assume this indicates that my company's network doesn't allow this type of traffic? Is there any way to find out what's going on?

KillrBuckeye said:

Okay, sorry for the triple post, but I have a new problem. I cannot connect to my home computer from my work computer. However, my brother was able to connect to my computer from his home computer. I assume this indicates that my company's network doesn't allow this type of traffic? Is there any way to find out what's going on?

Click to expand...

It's because your administrators at your work are smart and configured your work's firewall to be secure and block any outgoing/incoming ports that didn't need to be opened. Try talking to one of them and telling him you configured RDP at home so you can connect remotely from work to home and you modified your registry to change your RDP port for increased security and you'd appreciate it if they'd open that specific outgoing port. He might say no, he might say yes. Good chance he'll say no because it's not vital to the business and decreases security (depending on how concious he is regarding to security.

I'm pretty new to networking, firewalls, etc., so I'm not sure I understand how this works. I thought the RDP port number on my home computer was independent of the port number on my work's firewall or whatever. So you are saying that if I am using port number XXXX on my home computer/router, then my work computer/firewall must be able to receive information through that same port number? If so, then why was my brother able to connect to my computer if his Remote Desktop is still using the default port? Thanks for your help.

A firewall is a device which protects network resources by filtering incoming and/or outgoing (depends on firewall) packets based upon the port that packet will be using. Windows XP has a built-in firewall but it does not filter packets on the outgoing level, only the incoming level. Windows Vista will filter both directions. Some home routers also have firewall mechanisms. The thing is, routers aren't really setup in a secure nature right out of the box. They leave it up to the administrators to start closing ports and securing their network resources by themselves.

So in short, your brother hasn't closed the outgoing port (can't really do on cheap home routers). If he's only using the Windows XP firewall, outgoing ports can't be closed. If he's using a 3d party software firewall, he can close outgoing ports for his workstation only. Business firewalls are expensive and more robust allowing them to be heavily configured. These business firewalls allowed your administrator at work to close outgoing ports that are not needed.

Hope this helps.