Routing / Web Server Issue

Hey guys,

I have the following scenario:

I have a FreeBSD server just behind the router which I intend to use as a web server. I have set up apache and it works from inside my LAN just fine. From the outside though the connection on port 80 times out (i.e. nobody else can access my server). The router is configured to do port forwarding on port 80 to my server yet something is fishy. netstat on the server during the connection attempt from outside the network shows a SYN_RCVD..

So just to try it out I set up apache to listen on port 81 and did the port forwarding on the router.. Interestingly enough the http connection to :81 works just fine from the outside.

The router is a Linksys WRT54G, has its Firewall turned on with all options enabled, and has just a web interface which works both on port 80 and 443. I turned 80 off to see if that would do the trick (if the router was hogging port 80 just for itself) but no.. :\

This is the first time I have a problem like this, I hope some of you networking gurus would have more insights on it.
The problem is amost caused by your firewall configuration. It may disable :80 for some reasons. You should check the firewall's log file to see what happened.
After searching on the internet I think the problem is in my ISP blocking port 80 for non-commercial users. I have Cablevision. Anyone else who can confirm this?
You got a SYN on the outside interface from an external IP address? Then CV is probably not blocking it, unless they have a weird policy not allowing a SYN-ACK back out ...

"Port 80 is the primary port used by web servers to "listen" for incoming connections from web browsers. Activation of Port 80 is currently only available with Optimum Online® Boost. Please continue reading for more information, including activation instructions.

Port 80 Blocking
Because Port 80 is often used by malicious software, including viruses and worms, Optimum Online, like many ISPs, blocks this port for all standard Optimum Online customers."