source: mod_gnutls/README @ df34f08

mod_gnutls 

This module started back in September of 2004 because I was tired of trying to
fix bugs in mod_ssl.  mod_ssl is a giant beast of a module -- no offense to it's 
authors is intended -- but I believe it has fallen prey to massive feature bloat.

When I started hacking on httpd, mod_ssl remained a great mystery to me, and 
when I actually looked at it, I ran away.  The shear ammount code is huge, and it 
does not conform to the style guidelines.  It was painful to read, and even harder
to debug.  I wanted to understand how it worked, and I had recently heard about 
GnuTLS, so long story short, I decided to implement a mod_gnutls.

Lines of Code in mod_ssl: 15,324
Lines of Code in mod_gnutls: 3,594

Because of writing mod_gnutls, I now understand how input and output filters work, 
better than I ever thought possible.  It was a little painful at times, and some parts
lift code and ideas directly from mod_ssl. Kudos to the original authors of mod_ssl.

----------------------------

Author: Paul Querna <chip force-elite.com>

Heavily modified by Nikos Mavrogiannopoulos <nmav gnutls.org>

License: Apache Software License v2.0. (see the LICENSE file for details)

Current Status:
- SSL and TLS connections with all popular browsers work!
- Sets enviromental vars for scripts (compatible with mod_ssl vars)
- Supports Memcached as a distributed SSL Session Cache
- Supports DBM as a local SSL Session Cache
- Support for Server Name Indication
- Support for Client Certificates
- Support for TLS-SRP

Basic Configuration:

LoadModule gnutls_module  modules/mod_gnutls.so

# mod_gnutls can optionaly use a memcached server to store it's SSL Sessions.
# This is useful in a cluster enviroment, where you want all of your servers 
# to share a single SSL Session Cache.
#GnuTLSCache memcache "127.0.0.1 server2.example.com server3.example.com"

# The Default method is to use a DBM backed Cache.  It isn't super fast, but 
# it is portable and does not require another server to be running like memcached.
GnuTLSCache dbm conf/gnutls_cache

<VirtualHost 1.2.3.4:443>
    # insert other directives ... here ...

    # This enables the mod_gnutls Handlers for this Virtual Host
    GnuTLSEnable On

    # This is the Private key for your server.
    GnuTLSX509KeyFile conf/server.key

    # This is the Server Certificate.  
    GnuTLSX509CertificateFile conf/server.cert
</VirtualHost>

# a more advanced configuration
GnuTLSCache dbm "/var/cache/www-tls-cache/cache"
GnuTLSCacheTimeout 600
NameVirtualHost 1.2.3.4:443

<VirtualHost 1.2.3.4:443>
        Servername server.com:443
        GnuTLSEnable on
        GnuTLSPriority NORMAL
# To export exactly the same environment variables as mod_ssl to CGI scripts.
        GNUTLSExportCertificates on

        GnuTLSX509CertificateFile /etc/apache2/server-cert.pem
        GnuTLSX509KeyFile /etc/apache2/server-key.pem

# To enable SRP you must have these files installed. Check the gnutls srptool.
        GnuTLSSRPPasswdFile /etc/apache2/tpasswd
        GnuTLSSRPPasswdConfFile /etc/apache2/tpasswd.conf

# In order to verify client certificates. Other options to
# GnuTLSClientVerify could be ignore or require. The GnuTLSClientCAFile
# contains the CAs to verify client certificates.
        GnuTLSClientVerify request
        GnuTLSX509CAFile ca.pem
        ...
</VirtualHost>

# A setup for OpenPGP and X.509 authentication
<VirtualHost 1.2.3.4:443>
        Servername crystal.lan:443
        GnuTLSEnable on
        GnuTLSPriorities NORMAL:+COMP-NULL

# setup the openpgp keys
        GnuTLSPGPCertificateFile /etc/apache2/test.pub.asc
        GnuTLSPGPKeyFile /etc/apache2/test.sec.asc

# and the X.509 keys
        GnuTLSCertificateFile /etc/apache2/server-cert.pem
        GnuTLSKeyFile /etc/apache2/server-key.pem
        GnuTLSClientVerify ignore

# To avoid using the default DH params
        GnuTLSDHFile /etc/apache2/dh.pem

# these are only needed if GnuTLSClientVerify != ignore
        GnuTLSClientCAFile ca.pem
        GnuTLSPGPKeyringFile /etc/apache2/ring.asc
</VirtualHost>