Limit Apache to a single IP

Question

I've got a server with a bunch of IP addresses, and I only want Apache listening on one of them. It doesn't sound like a hard thing to do, and I've done it once before a while ago, but I'm having some trouble this time around. First off, here's where I'm at now, to my understanding:

Every place Apache is listening to port 80, it's listening only on the correct IP.

/etc/apache2$ grep -R ":80" .
./sites-available/default:<VirtualHost 192.168.0.82:80>
./httpd.conf:<VirtualHost 192.168.0.82:80>
./ports.conf:NameVirtualHost 192.168.0.82:80
./sites-enabled/000-default:<VirtualHost 192.168.0.82:80>

There's no mention of listening on 0.0.0.0.

/etc/apache2$ grep -R "0\.0\.0\.0" .

And yet... Apache refuses to start.

/etc/apache2$ sudo /etc/init.d/apache2 start
 * Starting web server apache2
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
Action 'start' failed.
The Apache error log may have more information.
                                                                         [fail]

In case someone asks, I'm not bound to that address:

/etc/apache2$ sudo netstat -nap | grep :80
tcp        0      0 192.168.0.83:80       0.0.0.0:*        LISTEN      2822/node

The error log at /var/log/apache2/error.log just says:

[Wed Aug 08 03:30:18 2012] [notice] caught SIGTERM, shutting down

Have I missed a spot in Apache's config? Is there something I'm not remembering to look for? Why is this not as simple as I remembered it being?

Answer 1

Apache binds to everything by default, even if you specify certain IP('s) to run NameVirtualHost on.

Add this in your ports.conf:

Listen 192.168.0.82:80

Reference: http://httpd.apache.org/docs/2.2/bind.html

Answer 2

Look in the /etc/apache2/ports.conf file.

You'll find a directive like:

Listen 80

The comment on CentOS boxes describes this option:

#
# Listen: Allows you to bind Apache to specific IP addresses and/or
# ports, in addition to the default. See also the <VirtualHost>
# directive.
#
# Change this to Listen on specific IP addresses as shown below to
# prevent Apache from glomming onto all bound IP addresses (0.0.0.0)
#
#Listen 12.34.56.78:80

For what you want, change the Listen 80 line to Listen 192.168.0.82:80.

You are not able to start Apache right now because it is attempting to bind to port 80 on all interfaces (the 0.0.0.0 designation), and you have node listening on 192.168.0.83:80.

The IP in the virtual host blocks means that that particular virtual host will respond on requests coming in on that IP address. It doesn't specify how Apache will bind to the interfaces it sees.

Answer 3

Listen directive is what you're looking for:

Listen 192.168.0.82:80

More info in documentation.

Answer 4

Use the following as per the Apache docs:

Listen 192.168.0.82:80

In some circumstances (not all), one could go a bit further and do this:

Listen some_name_in_my_localhost:80

That way you make your apache configs portable in situations when you have an Apache server farm. There are pros and cons to this (just like with everything else.)