Network troubleshooting, any experts?

[Jeff Vian]

Elam Daly 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.

IPTABLES does stateful filtering and related connection can be 
established while new connections can be blocked.  I use this on both 
ftp (allowing only port 20) and http (allowing only port 80).
A connection estqablished as a reply to a web browser request is related 
and can be allowed without being explicitly allowed by port number..
Any TCP connection that originates from the server is new and easily 
blocked.

It may be that they are using a similar firewall rule on this particular 
host.
Check how your ISP has the router/firewall configured and make sure they 
allow this host outbound connections. (As they apparently do for other 
hosts.)