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Contributor
TheJanitor
Posts: 5
Registered: ‎02-20-2012
Accepted Solution

Remote Desktop through Motorola SVB5220 cable modem fails

Hello!  Trying to set up remote desktop to one of my machines, and I'm pulling my hair out!

 

I have a home network behind a Linksys WRT110 router which is behind the Comcast-provided Motorola SVB5220 modem. Here's what I've done to date:

 

  • The Comcast-provided Norton firewall has been set allow all traffic to/from \windows\system32\mstsc.exe.
  • The router has been set to forward both TCP and UDP of external port 3389 to port 3389 on the static LAN-side IP address set up for the W7Pro machine from all.
  • I've set up RDP on the Windows 7 Professional machine and verified setup by connecting to it from another machine on the LAN side of the router.
  • ipconfig confirms the correct static IP is assigned to the W7P machine
  • netstat confirms that the machine is listening on port 3389 for all interfaces on the WP7 machine (TCP 0.0.0.0:3389 0.0.0.0:0 LISTENING)

    I cannot connect from the WAN side. Going to canyouseeme.org and scanning for port 3389 (or, as it turns out, any other port that is forwarded via the linksys router) responds with a connection timeout.

 

My question: does the Motorola SVB5220 include a firewall of its own? If so, how can I access it in order to configure it? Or do I need to have Comcast place the modem in "bridge" mode or some such to let my router do the job?

 

If no to the above, where, if you can tell from what I've provided, have I gone wrong? No document I can find concerning ports Comcast intentionally blocks lists any of the ports I've configured to forward - which, notably, all fail when I go to canyouseeme.org.

 

Thanks for any insight you can provide!

 

 

Networking Expert
Baric
Posts: 24,238
Registered: ‎07-28-2003

Re: Remote Desktop through Motorola SVB5220 cable modem fails

[ Edited ]

No, there is no firewall per se in the SBV5220.  Ports CAN be blocked by Comcast using the boot configuration file when the modem is initialized, this is how port 25 blocks are usually handled.  But it's not standard practice to block 3389 and I suspect this is NOT your problem.

 

Things to try:

 

  1. Verify your public IP address.  if you are hitting the wrong IP, nothing will work.  I assume you have already checked this but it can't hurt to be sure.
  2. Disable the Norton firewall entirely.  Personally I would remove Norton entirely, the combo of the Windows firewall and free Microsoft Security Essentials for virus protection is more than enough compared to the mess that is Norton, just my opinion.
  3. Reset the Motorola to defaults and let the modem reinitialize from scratch.  The admin site for most Motorola modems is very similar, so look for a Reset All Defaults button near the bottom of the Configuration page.  On my SB6120, it's here: http://192.168.100.1/cmConfig.htm
  4. Verify the port forwarding rule on the WRT110 is Enabled and that the IP address for the target is correct.
  5. Reset the WRT110 to factory defaults and re-configure from scratch.

 

Contributor
TheJanitor
Posts: 5
Registered: ‎02-20-2012

Re: Remote Desktop through Motorola SVB5220 cable modem fails

Oddness! At your suggestion, I turned off Norton Firewall for 15 minutes to test, and, sure enough, I can reach the box from outside. But get this: I turn Norton back on and, lo and behold - it STILL works! I can still reach the box. Lesson learned: cycle the firewall after making any changes. Thanks.
Networking Expert
Baric
Posts: 24,238
Registered: ‎07-28-2003

Re: Remote Desktop through Motorola SVB5220 cable modem fails

Gee, Norton causing a problem, imagine that... :smileydevil: