TCP Port 80 is filtered on Ubuntu 8.04

janeLHX · 06-05-2009, 06:25 PM

Dear friends,

I have this problem from the beginning, when I have just started using my new dedicated server with Ubuntu 8.04 LTS - Plesk 8.6 - 64bit.

From time to time, all of the sudden, day or nigh, once a week, or 4 times a day my site stops working, and all of my users get the error "unable to connect" in their browsers. I just know that when this happens I can only access Plesk panel on port 8443, and restart the server, and after that everything woks fine. I have noticed that when my site works fine and I type the command nmap -sT -O localhost I get the message that the port 80 is open, but when the site is down I get that the port is filtered, "80/tcp filtered http".

Can you please tell me what could be the problem ?

Matir · 06-05-2009, 08:20 PM

Is apache running successfully? Are there any firewalls in place? What does nmap show for other ports?

janeLHX · 06-06-2009, 04:16 AM

Code:

Not shown: 1696 closed ports
PORT     STATE    SERVICE
21/tcp   open     ftp
22/tcp   open     ssh
25/tcp   open     smtp
53/tcp   open     domain
80/tcp   filtered http
106/tcp  open     pop3pw
110/tcp  open     pop3
143/tcp  open     imap
443/tcp  open     https
465/tcp  open     smtps
953/tcp  open     rndc
993/tcp  open     imaps
995/tcp  open     pop3s
3000/tcp open     ppp
3306/tcp open     mysql
5432/tcp open     postgres
8009/tcp open     ajp13
8443/tcp open     https-alt

Port 443 is open so I presume that the Apache is working, all other ports are unchanged except this one.

And here is my firewall configuration in Plesk panel.

http://www.dodaj.rs/f/2L/k0/1ME8IBOJ/firewall.jpg