Special Environment Variables

BrowserMatch "Mozilla/2" nokeepalive

Apache provides a set of special environment variables. If one of those variables is set, Apache will modify its behavior. They are commonly used to work around buggy clients. For example, the nokeepalive variable disables keepalive support in Apache. This reduces performance on the server, since multiple requests cannot be transmitted over the same connection. Hence, it should only be set when the request is made by a client that does not correctly support this functionality, typically using a BrowserMatch or SetEnvIf directive, as shown in the example.

In the appendix you can find a list of all the special environment variables. Chapters 7 and 8 include examples of special variables used to work around issues with SSL and DAV implementations.