ucarp - 1.5.2-2.2 main

UCARP allows a pair of hosts to share common virtual IP addresses in
order to provide automatic fail-over. It is a portable user-land
implementation of the secure and patent-free Common Address Redundancy
Protocol (CARP, OpenBSD's alternative to the VRRP).
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Strong points of the CARP protocol are: very low overhead,
cryptographically signed messages, interoperability between different
operating systems and no need for any dedicated extra network link
between redundant hosts.