Debian includes HAVP. Please have a look at: https://packages.debian.org/de/sid/havp Additional information:
pfSense includes HAVP. Please have a look at: https://doc.pfsense.org/index.php/HAVP_Package_for_HTTP_Anti-Virus_Scanning Additional information:
There is a OpenBSD Port available. Please have a look at: http://www.openbsd.org/cgi-bin/cvsweb/ports/www/havp/
There is a FreeBSD Port available. Please have a look at: http://www.freshports.org/www/havp/