Network troubleshooting, any experts?

[david]

At 05:27 PM 4/28/2004, you wrote:
>Jeff Vian wrote:
>
>>\My thoughts are that they probably know this is a server, and as such 
>>may have blocked TCP from that particular host IP address.
>>
>>It appears UDP and ICMP are getting through.
>They do know it's a web server, as they host our website.  If TCP is being 
>blocked though, how is it possible that can people visit the
>website?  I realize that http connections come in through port 80, but the 
>responses from the webserver don't.  They leave from the
>webserver through any port that apache deems neccessary, correct?
>Elam Daly
>Whiteware Inc.

Elam

As far as I know (and that is very little), most blockings occur on inbound 
connections.  Thus, if your web-site is listening to port 80, and port 80 
is blocked either by you or by your ISP or by your corporation, your out of 
luck.  Unless, of course, you can convince the blocking agency to unblock 
that port to your server.

On the other hand, being behind one of those port-80 blocking ISPs myself 
(compounded by having a dynamic IP address and running behind a NAT), I've 
simply directed my web server to listen on a high-numbered port. (like 
12345), and made sure that the links that point to my server include the 
port number.  If you need further advice on how to accomplish this act of 
black-magic, even with a dynamic address, please ask.

David