How to remove Server: header from the HTTP response with Apache?
If you set ServerTokens to "Prod", you can reduce the header to "Server: Apache". See documentation for full list of options:
Documentation for Apache 2.2
Documentation for Apache 2.4
Note: The settings are the same in both versions however the 2.4 documentation adds this note:
Setting ServerTokens to less than minimal is not recommended because it makes it more difficult to debug interoperational problems. Also note that disabling the Server: header does nothing at all to make your server more secure. The idea of "security through obscurity" is a myth and leads to a false sense of safety.
If you want to remove the word "Apache" entirely, you'll have to modify the source.
You can remove or mask the server identification from the Http-Header by using the ModSecurity open source web application firewall.
Server identity masking
One technique that often helps slow down and confuse attackers is the web server identity change. Web servers typically send their identity with every HTTP response in the Server header. Apache is particularly helpful here, not only sending its name and full version by default, but it also allows server modules to append their versions too.
To change the identity of the Apache web server you would have to go into the source code, find where the name "Apache" is hard-coded, change it, and recompile the server. The same effect can be achieved using the
SecServerSignature directive:
SecServerSignature "Microsoft-IIS/5.0"It should be noted that although this works quite well, skilled attackers (and tools) may use other techniques to "fingerprint" the web server. For example, default files, error message, ordering of the outgoing headers, the way the server responds to certain requests and similar - can all give away the true identity. I will look into further enhancing the support for identity masking in the future releases of mod_security.
If you change Apache signature but you are annoyed by the strange message in the error log (some modules are still visible - this only affects the error log, from the outside it still works as expected):
[Fri Jun 11 04:02:28 2004] [notice] Microsoft-IIS/5.0 mod_ssl/2.8.12 OpenSSL/0.9.6b \ configured -- resuming normal operationsThen you should re-arrange the modules loading order to allow mod_security to run last, exactly as explained for chrooting.
Note
In order for this directive to work you must leave/set ServerTokens to Full.
When the SecServerSignature directive is used to change the public server signature, ModSecurity will start writing the real signature to the error log, to allow you to identify the web server and the modules used.