Pound and Pen - Simple Load Balancing

Pound and Pen - Simple Load Balancing: "Pound and Pen are simple web server load balancers licensed under the GPL that run mainly on Unix based operating systems. Pound is a web (port 80) load balancer only, unlike Pen which is designed to balance any simple TCP/IP protocol, including http, smtp, ftp, and others. Before you decide to load balance your website with one of these software programs there are several other considerations you may want to understand."
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Pen Load Balancer - http://siag.nu/pen/
Pound Load Balancer - http://www.apsis.ch/pound/
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Extracting remote_ip is easily done with mod_extract_forwarded
Pound mailing list has this information.
Or this one is good, with mod_rpaf.