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Joel on Software

ASP .Net application through a Linksys firewall

I have an ASP .Net program that uses the URL

going through port 81

I do this cause I have a dynamic IP from COMCAST and a program called DIRECTUPDATE update the proxy server for me to get to my program.

If I open port 81 in Windows XP Firewall I can get through and all is well.

But new PCs require me to use a Linksys router and even though I set up port triggering on port 81 I or noone else can get through the router.

Anyone else successfully using DIRECTUPDATE with ASP.Net or have any ideas as to what I need to set?

Gary Miller
Friday, November 26, 2004

My first try would be to try using port forwarding instead of port triggering. I have a D-Link router at home, and never have a problem with port forwarding. I can SSH, access my web server, etc, all on different forwarded ports. I think we tried to set up port triggering one time for an AIM app my wife wanted to run on her machine and had a dickens of a time trying to set it up.

My second thing would be to see what ports are actually open at your IP address. For example, I can see what Comcast IP address you are using at that DNS entry. I ran a quick scan on it:

foyc@dilbert foyc $ nmap -sT -p 80-81 -P0 -T Polite

Starting nmap 3.50 ( ) at 2004-11-27 10:11 EST
Interesting ports on (
80/tcp filtered http
81/tcp closed  hosts2-ns

Nmap run completed -- 1 IP address (1 host up) scanned in 19.797 seconds

Which shows to me that 81 is not showing as open from your router. Until it does no one will be able to access you.

Feel free to email me privately if you want me to check changes for you.


Cory Foy (
Saturday, November 27, 2004

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