What is blocking port 80?

[Longman, Bill]

> Filtered means that the port is not responding in any way, as 
> opposed to
> closed, which means that the port specifically responds that 
> it is closed.
> Unfortunately, running nmap from a remote machine outside your network
> won't tell you whether it's the router filtering the packets 
> or YDL. You
> would need to run nmap within your network to the private IP of the
> machine in question. But in your case, nmap pretty much won't tell you
> anything you don't already know because you can already 
> successfully point
> a browser within your network to the YDL machine's private 
> IP. This means
> that the Apache configuration is definitely at fault. Perhaps you have
> virtual hosts turned on? On your machine, Apache apparently 
> is set up to
> recognize the machine referred to only as 192.168.1.105 and 
> not recognize
> the same machine as 199.21.148.227.

No way, it's got to be the exact opposite, Dan. If YDL is returning pages to
the inside and nmap is showing an open port 80 on the inside, then it's got
to be the port forwarding problem at the firewall.

Apache will still handle requests it sees on its interface, despite what the
hostname might be configured in the httpd.conf file. Apache definitely won't
respond on a different port unless it's told to, so that might be your next
test, Cam, although I think it's a waste.

Why were you trying to port forward anyway? Do you have more than one web
server you want to access? If that's the case, you can proxy them through
one Apache server.

 --> ext:80 FW int:81 --> int:81 YDL

If this is what you were trying to do, you should have been able to get
pages on your internal network from the Apache server's port 81. You'd have
needed URLs like http://ydlinteral:81/foo.html. If that hadn't worked, you'd
have never gotten any pages sent out. At all.