SSL/TLS Strong Encryption: Compatibility

All PCs are compatible. But some of them are more compatible than others.

-- Unknown

Here we talk about backward compatibility to other SSL solutions. As you perhaps know, mod_ssl is not the only existing SSL solution for Apache. Actually there are four additional major products available on the market: Ben Laurie's freely available Apache-SSL (from where mod_ssl were originally derived in 1998), Red Hat's commercial Secure Web Server (which is based on mod_ssl), Covalent's commercial Raven SSL Module (also based on mod_ssl) and finally C2Net's commercial product Stronghold (based on a different evolution branch named Sioux up to Stronghold 2.x and based on mod_ssl since Stronghold 3.x).

The idea in mod_ssl is mainly the following: because mod_ssl provides mostly a superset of the functionality of all other solutions we can easily provide backward compatibility for most of the cases. Actually there are three compatibility areas we currently address: configuration directives, environment variables and custom log functions.