apache server not listening on port 80

Question

Both my workstation and server are on the same lan segment and can ping each other (and I can ssh into the server from my workstation without issues).

Did a default install of apache on centos 7.

Started the service, but I cannot browse to my webserver from my workstation.

nmap report port 80 is filtered.

I disabled SELinux on the server but the port is still filtered.

Here is what netstat -l gives me:

Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN
tcp        0      0 localhost:smtp          0.0.0.0:*               LISTEN
tcp6       0      0 [::]:http               [::]:*                  LISTEN
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN
tcp6       0      0 localhost:smtp          [::]:*                  LISTEN
raw6       0      0 [::]:ipv6-icmp          [::]:*                  7

Weirdly netstat -na shows port 80 as listening, but for ipv6 (though I read somewhere this doesn't necessarily mean its not listening on ipv4 either)

Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN
tcp        0     64 10.1.1.1:22             10.2.2.2:44939        ESTABLISHED
tcp6       0      0 :::80                   :::*                    LISTEN
tcp6       0      0 :::22                   :::*                    LISTEN
tcp6       0      0 ::1:25                  :::*                    LISTEN
raw6       0      0 :::58                   :::*                    7

Here are relevant part of my /etc/httpd/conf/httpd.conf (which I have not modified)

<Directory />
    AllowOverride none
    Require all denied
</Directory>

<Directory "/var/www">
    AllowOverride None
    # Allow open access:
    Require all granted
</Directory>

<Directory "/var/www/html">

    Options Indexes FollowSymLinks
    AllowOverride None
    Require all granted
</Directory>

<Files ".ht*">
    Require all denied
</Files>

The service seems to be running ok:

httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
   Active: active (running) since Fri 2015-10-02 08:36:40 EDT; 1h 27min ago
  Process: 23294 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)
 Main PID: 23302 (httpd)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"
   CGroup: /system.slice/httpd.service
           ├─23302 /usr/sbin/httpd -DFOREGROUND
           ├─23303 /usr/sbin/httpd -DFOREGROUND
           ├─23304 /usr/sbin/httpd -DFOREGROUND
           ├─23305 /usr/sbin/httpd -DFOREGROUND
           ├─23306 /usr/sbin/httpd -DFOREGROUND
           └─23307 /usr/sbin/httpd -DFOREGROUND

Why isn't it listening on port 80?

Answer 1

As Michael Hampton has commented on your post, I'd bet that your firewall (iptables) is blocking your traffic.

Either disable it (systemctl disable firewalld), or tell it to allow traffic on port 80 (firewall-cmd --zone=public --add-port=80/tcp --permanent).

Answer 2

The fact that port 80 is filtered or not is not relevant for the netstat output. Even if iptables is configured to block (DROP or REJECT) connection to that port you should see that Apache is listening to the 80 port.

The point is that httpd is configured to listen to BOTH IPv4 and IPv6 ANY addresses (0.0.0.0 and ::) and, in that case, netstat shows only the IPv6 one. The explanation is here:

https://bugs.launchpad.net/ubuntu/+source/net-tools/+bug/657270

In short: in that case the IPv6 connection is capable of serving BOTH protocols and so only one socket is opened. And since only one socket is opened, only one socket is showed in the netstat output.

Answer 3

Check iptables rules (iptables-save) and see if port 80 is allowed.

For testing purposes you can do service iptables stop or iptables -F.