See what software UCarp is at [[http://www.pureftpd.org/project/ucarp | its own home page]].

Here is a patch I wrote against version 1.5.2, to:
* use the working NIC's MAC address as source of multicast or broadcast advertisement packets
* fix typo in option description string, so that "-o" argument works (from Debian)
* add a missing shutdown case (from Debian)

The patch file: [[(Attach:)ucarp-1.5.2-srcmac.patch]].