I run a system that has a Pound reverse proxy in front of a squid accelerator, in turn in front of Apache2 powering a few PHP-based webapps.
The Pound daemon is configured to send X-Forwarded-For headers to Apache so the aforementioned applications can determine the true source of a message (squid is configured to transparently pass on the X-Forwarded-For headers without modification). However, Pound notates IPv4 addresses in XFF headers like
::ffff:18.104.22.168 instead of simply as
22.214.171.124, and this throws off the applications.
Aside from modifying each application to correctly handle the
::ffff:126.96.36.199 case, is there a way to either stop Pound from using the IPv6 notation or in Apache to preemptively convert the IPv6 notation back to IPv4 notation?