Ubuntu Hardy - Apache configuration #2

Continuing from the first Ubuntu Hardy Apache configuration article, we'll now look at some of the other settings in the main apache2.conf file and what they can do.

Concentrating on efficiency and security, this will end our apache2.conf journey (for now).

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ServerName

Default: Not Set

The ServerName is usually a hostname or a FQDN (Fully Qualified Domain Name).

If you followed the Ubuntu Hardy installing Apache and PHP5 article, you will have already set the ServerName configuration.

If you fail to set the ServerName then on an Apache restart you will see the following warning:

apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName

To stop the warning and set the ServerName, add the following to the apache2.conf:

ServerName demo

Remember the test slice has a hostname of 'demo' - set this to your hostname or FQDN.

HostnameLookups

Default:

HostnameLookups Off

If you want happy users and to save traffic, keep this at Off.

Setting this to 'On' will enable DNS lookups so host names can be logged (it performs a reverse DNS check), setting it to 'Double' will not only perform the reverse DNS check it will then check the resulting hostname.

All a bit much and if you desperately need hostname information from your visitors it is advised to use logresolve (located in /usr/sbin/logresolve) for this purpose. A small explanation can be found here.

ServerTokens

Default:

ServerTokens Full

The ServerTokens setting will dictate how much information is sent in the Headers with regard to Apache version and modules in use.

The default (Full) would send something like this:

Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5 with Suhosin-Patch Server

Does this make a difference? Well, yes. If we can suppress that information it will make it harder for someone to find an exploit.

It does not make the actual install any more secure but all someone has to do right now is look for an exploit in Ubuntu Apache 2.2.8 and so on. Why make it easy for them?

The options are (with example outputs):

Full

Apache/2.2.8 (Ubuntu) PHP/5.2.4-2ubuntu5 with Suhosin-Patch Server

OS

Apache/2.2.8 (Ubuntu) Server

Minimal

Apache/2.2.8 Server

Minor

Apache/2.2 Server

Major

Apache/2 Server

Prod

Apache Server

It's up to you what level of info you want to give out. I prefer setting ServerTokens to Prod.

ServerSignature

Default:

ServerSignature On

Server generated pages, such as 404 pages or directory listings, can contain a footer line which includes server information and can include the ServerAdmin email address.

If you navigate to your Slice IP address and a non-existent page:

http://123.45.67.890/blahblah

You will see a 404 Page not found page with the footer information:

The options are:

Off: Produces no footer

On: Produces footer information (at a level defined by the ServerTokens setting)

Email: Adds an email link to the information (email address is defined in the vhosts file with the ServerAdmin setting)

It doesn't work!

If you are experimenting with the settings in the main apache2.conf file and find that changing the ServerSignature setting does nothing then keep in mind that many settings can be overridden by the virtual host file.

In this case, the default virtual host file has:

ServerSignature On

So open the file:

sudo nano /etc/apache2/sites-available/default

Change the ServerSignature to On, Off or Email. You can even delete the ServerSignature setting from the vhost file so it takes it from the apache2.conf.

Reload Apache after any changes to the virtual host file and voilà! All is good.

Summary

Some simple steps in this article but ones which I believe are very useful and aid in increasing the efficiency of your Slice and assist in the overall security effort on your Slice.

PickledOnion.