Checking your network connectivity, open ports

At your server console:

root@yourserver:/web/ehcp# nmap localhost

Starting Nmap 4.53 ( http://insecure.org ) at 2009-04-06 03:44 EDT
Interesting ports on localhost (127.0.0.1):
Not shown: 1702 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
53/tcp open domain
80/tcp open http
110/tcp open pop3
143/tcp open imap
953/tcp open rndc
993/tcp open imaps
995/tcp open pop3s
3306/tcp open mysql
8080/tcp open http-proxy

Nmap done: 1 IP address (1 host up) scanned in 0.284 seconds
root@yourserver:/web/ehcp#

From outside of your server, from a different location:

root@yourserver:/web/ehcp# nmap localhost

Starting Nmap 4.53 ( http://insecure.org ) at 2009-04-06 03:44 EDT
Interesting ports on localhost (127.0.0.1):
Not shown: 1702 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
110/tcp open pop3
143/tcp open imap
953/tcp open rndc
993/tcp open imaps
995/tcp open pop3s
3306/tcp open mysql
8080/tcp open http-proxy

Nmap done: 1 IP address (1 host up) scanned in 0.284 seconds
root@yourserver:/web/ehcp#

These should be same, outside and local... Otherwise, some ports are blocked in your network... Consult your network or server provider...
In this example, ports 20,21, 25,53 are blocked from outside, not blocked from inside your server,
That means, necessary services, ftp, smtp, dns working on your server, but not reachable from outside...

You may also check your port status from outside: http://www.ehcp.net/other/portstatus.php

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