no iptables, no selinux, port 81 in virtualhost still not working

Question

I try to open port 81 as a virtualhost. after setting apache, I can CURL localhost:81 from local machine and get response(yes it was listening port 81). However, when visit the same address from remote browser, browser always show TIME OUT error.

I thought it might be due to firewall or selinux, so I disable both of them and try again but still failed. The commands I used to disable selinux and firewall are as below:

to disable selinux:

open /etc/selinux/config and change SELINUX=disabled and then reboot. I use sestatus command to check and output shows it was disabled.

to close iptables:

service iptables stop
chkconfig iptables off

and I close ip6tables either:

service ip6tables stop
chkconfig ip6tables off

I am using CentOS 6.3. Are there other security issues besides selinux and iptables that I didn't notice?

Add more information

I use IP address directly, like 123.123.123.123:81. I don't think it is due to apache conf since I can get response from local server machine through both curl locahlost:81 and curl 123.123.123.123:81.

Netstat result

after running netstat command, I got the

tcp        0      0 :::80                       :::*                        LISTEN      1809/httpd          
tcp        0      0 :::81                       :::*                        LISTEN      1809/httpd  

seems both 80 and 81 are working.

Ifconfig

here is the ifconfig -a result:

eth0  Link encap:Ethernet  HWaddr 00:50:56:9B:24:D6  
      inet addr:101.251.235.162  Bcast:101.251.235.163  Mask:255.255.255.252
      inet6 addr: fe80::250:56ff:fe9b:24d6/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:16046 errors:0 dropped:0 overruns:0 frame:0
      TX packets:15092 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:3370807 (3.2 MiB)  TX bytes:2352380 (2.2 MiB)

lo    Link encap:Local Loopback  
      inet addr:127.0.0.1  Mask:255.0.0.0
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING  MTU:65536  Metric:1
      RX packets:70 errors:0 dropped:0 overruns:0 frame:0
      TX packets:70 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0 
      RX bytes:19119 (18.6 KiB)  TX bytes:19119 (18.6 KiB)

Answer 1

First check to make sure that your server is listening on the port you want, not just local host

netstat -plnt

Should give you an output similar to this:

Proto Recv-Q Send-Q Local Address   Foreign Address  State       PID/Program name
tcp        0      0 127.0.1.1:53     0.0.0.0:*       LISTEN      -               
tcp        0      0 10.0.3.1:53      0.0.0.0:*       LISTEN      -               
tcp        0      0 127.0.0.1:631    0.0.0.0:*       LISTEN      -               
tcp        0      0 127.0.0.1:6680   0.0.0.0:*       LISTEN      -       

Check the Local Address column to make sure your server is listening on *:81 or ip.ad.dr.ess:81 and not just localhost:81 or 127.0.0.1:81

If that's the case, check httpd.conf and make sure that the server is set to Listen *:81 and not Listen localhost:81

If you httpd.conf is fine, check your virtual host config too, to make sure your listening to everything

<VirtualHost *:81>