Can't listen on port 80 with my server

Question

Very new on this kind of issue, i am trying to launch a server on the port 80 (it's important to me to use this specific port).

It's fails, but it works on other ports (even < 1024 when i am root, but still fail on the port 80).

I probably have something running on the port 80, i would like to identify it in order to change its listening port.

I saw this cmd can help to see the state of a specific port: netstat -ano|grep 80|grep LISTEN but i am not sure tu understand well the result.

Here is what i get:

tcp        0      0 127.0.0.1:28017         0.0.0.0:*               LISTEN      off (0.00/0/0)
tcp6       0      0 :::80                   :::*                    LISTEN      off (0.00/0/0)
unix  2      [ ACC ]     STREAM     LISTENING     8805     /tmp/mongodb-27017.sock
unix  2      [ ACC ]     STREAM     LISTENING     13112    /home/me/.pulse/04d802bb34ddb9da49b1f9060000000b-runtime/native

I read on the line 2 that the port 80 seems to be not listening, but don't understand further.

UPDATE:

sudo lsof -i :80

COMMAND    PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
apache2   1107     root    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
apache2   1131 www-data    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
apache2   1132 www-data    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
apache2   1133 www-data    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
apache2   1134 www-data    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
apache2   1136 www-data    4u  IPv6   7630      0t0  TCP *:http (LISTEN)
ubuntu-ge 2095     me    7u  IPv4  82145      0t0  TCP me-Ubuntu.local:43345->mulberry.canonical.com:http (CLOSE_WAIT)

Thanks (i am using ubuntu) !

Solution 1

If this is Linux (and perhaps some other UNIXes as well, though not MacOS), try running the following:

sudo netstat -lnp

You'll get output similar to the following:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
...
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     26156/apache2       
...

I'll list the interesting parts:

• Local Address: 0.0.0.0:80 - The address in question is port 80 on all interfaces.
• State: LISTEN - It's listening
• PID/Program name - 26156/apache2 - The ID and name of the process that's listening to the port.

You basically want to to make sure the program mentioned above isn't running (e.g., in my case, I'd have to shutdown the apache2 daemon, and configure the OS to not automatically start it up on next boot).

On the other hand, if you just want to get this fixed quickly, you can kill the process:

kill -9 <pid>

In my example:

kill -9 26156

The problem will of course return the next time you reboot, or someone starts up that service.

Solution 2

You can use lsof to find out:

sudo lsof -i :80

If you don't have lsof, install it with

sudo apt-get install lsof

lsof is like swiss army knife tool to tell who is holding files and sockets open.

Comments

[Jack Leow]

Is this Linux? Or some other flavor of UNIX?

[Devin Stewart]

the :::80 is telling you something is listening of port 80 via ipv6, :: is the equivalent of 0.0.0.0 in ipv4. mvp's answer below should give you what process is running on port 80 currently.

[Kien Truong]

Shouldn't this be on Serverfault ?

[Eliah Kagan]

This will likely be considered off-topic for Stack Overflow. You might want to ask about this on Ask Ubuntu, Unix.SE, or Super User (but search for it there first!).

[Ludo]

I updated the main post with the result, Apache seems to be listening on this port, but i guess it have to in order to match the HTTP requests...? (Sorry i am lost^^)

[Ludo]

Ok thanks for the explanations, yes apache is the program running on port 80 in my case too. Is it a good id to change its port ? I guess apache has to match the http requests so i don't want to do some wrong opearations on it...

[mvp]

You must have another apache instance started and bound to port 80. You should stop it first: sudo service apache2 stop. In other words, lsof should not show any process listening on 80, otherwise you will not be able to start another one.

[Ludo]

Yes i understood this point but is there a way to make apache working on another port ? Because i need it to make my domain match with a specific path (where there is my webapp), then i need a nodejs server listening on port 80.

[mvp]

yes, you can make apache work on any port. But remember that any other port most likely will be firewalled for most users of your site. Better option would be to use ProxyPass from Apache into nodejs working on some internal port

[Jacek Pietal]

works in my case showed apache2 which i stopped as a daemon >;-O