[ Thanks to linuxconfig.org for this link.
]
“Two-way SSL authentication also known as mutual SSL
authentication allows SSL client to confirm an identity of SSL
server and SSL server can also confirm an identity of the SSL
client. This type of authentication is called client authentication
because SSL client shows its identity to SSL server with a use of
the client certificate. Client authentication with a certificate
can add yet another layer of security or even completely replace
authentication method such us user name and password.“In this document, we will discuss configuration of both types
of SSL authentication one-way SSL authentication and two-way SSL
authentication.”