I can't access my server remotely at port 80. First of all, I did not set it up. Someone else did. I am not a sysadmin. But communication between both parts (me and sysadmin) takes time and deadlines await, so I decided to take matters into my own hands. After all I have root access.

It seems to me there is a Firewall issue, but how can I resolve it?

This is what I get from my side:

chris@mint-desktop ~ $ nmap -Pn remote_server -p 80

Starting Nmap 6.00 ( http://nmap.org ) at 2014-07-01 16:28 EEST
Nmap scan report for remote_server (remote_addr)
Host is up.
rDNS record for remote_addr: rDNS_record_for_remote_addr_seems_valid
80/tcp filtered http

Nmap done: 1 IP address (1 host up) scanned in 2.13 seconds

This is what I get server-side:

~# ps ax|grep "apache"
 5620 ?        Ss     0:13 /usr/sbin/apache2 -k start
 6203 pts/2    S+     0:00 grep apache
21115 ?        S      0:00 /usr/sbin/apache2 -k start
21168 ?        S      0:00 /usr/sbin/apache2 -k start


~# netstat -ntlp | grep :80
tcp6       0      0 :::80                   :::*                    LISTEN      5620/apache2


~# iptables -L -n
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination 


cat /var/log/apache2/access.log
::1 - - [29/Jun/2014:07:35:02 +0100] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Debian) (internal dummy connection)"
::1 - - [29/Jun/2014:07:35:02 +0100] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Debian) (internal dummy connection)" - - [30/Jun/2014:15:02:00 +0100] "GET / HTTP/1.1" 304 209 "-" "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko"

However, when I hit the remote name on my web browser, I get no response. Logs say that there was a hit yesterday internally, but no external access. So, I guess the sysadmin tested it and realized it was up. But I can't access it.

  • 2
    It's firewalled somewhere else. What is between you and the server? Jul 1 '14 at 14:07
  • I don't know. I will have to ask...
    – xpanta
    Jul 1 '14 at 14:14
  • What kind of external firewall do you have? This may help aid a sys admin to tell you what to add to your firewall config to open it up.
    – VirtualSA
    Jul 1 '15 at 18:17

It looks like you have a private IP on your server. So you need a DNAT / port forwarding rule on the gateway that directs to port 80 on the web server.

  • Thanks. If external request is blocked by a intermediate gateway then I guess there is nothing I can do to fix that. Can I check that myself? Or wait for a sysadmin response?
    – xpanta
    Jul 1 '14 at 14:15
  • If my assumption is true, you need admin access to the router to fix it.
    – Peter
    Jul 1 '14 at 19:24

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