ucarp allows a pair of hosts to share common IP addresses in
order to provide automatic failover of an address from one machine to
another. It is a portable userland implementation of the secure and
patent-free Common Address Redundancy Protocol, (CARP), OpenBSD's
alternative to VRRP.
ucarp supports the following command line options:
-i INTERFACE --interface=INTERFACE
The network interface to bind to.
-s IPADDRESS --srcip=IPADDRESS
The persistent source address, (real IP), associated with this
-v VHID --vhid=VHID
The id of the virtual server [1-255].
-p PASSWORD --pass=PASSWORD
The shared password, (this gets encrypted and is not sent in the
-o PASSFILE --passfile=PASSFILE
File to read the shared password from. The file specified
should contain the password on the first line of the file.
Turn on preemptive failover. This causes an instance of
ucarp to assume master status right immediately.
Do not run the downscript on startup when the
initial state is backup.
-a IPADDRESS --addr=IPADDRESS
The IP address of the virtual server.
Display a brief summary of the command line options.
-b SECONDS --advbase=SECONDS
Interval in seconds that advertisements will occur, (defaults
to 1 second).
-k SKEW --advskew=SKEW
Advertisement skew [1-255], (defaults to 0).
-u COMMAND --upscript=COMMAND
Specifies the command to run after ucarp has successfully
become master, the interface name gets passed as an argument.
Typically a script used to bring up the virtual address, log the
result, add routes, clear arp cache entries, etc.
-d COMMAND --downscript=COMMAND
Specifies the command that is run after ucarp has
transitioned to the backup state, the interface name is passed
as an argument. This is typically a script used to bring down
the virtual interface, log the action, remove routes, etc.
-r RATIO --deadratio=RATIO
Ratio used by the backup to determine how long to wait for an
unresponsive master before considering it dead.
Use of this command causes the command specified by the -d
argument to be invoked when ucarp shuts down.
Causes ucarp to detach from the terminal and run in the
background as a daemon.
Set the syslog facility, defaults to daemon.
-x PARAMETER --xparam=PARAMETER
Specify an extra parameter to be supplied to the up/down
Ignore unplugged network cables. This option is useful when
ucarp nodes are connected with a crossover cable. Without
this option the master will transition to backup when the other
node is powered down, as it no longer has a link (NO-CARRIER).
Use broadcast instead of multicast advertisements.
A host with a real IP of 10.1.1.10 configured to be the master
in a preemptive configuration with a virtual IP of 10.1.1.252.
This manual page was written by Eric Evans <firstname.lastname@example.org>
for the Debian system (but may be used by others). Permission is
granted to copy, distribute and/or modify this document under
the terms of the GNU General Public License, Version 2 or any
later version published by the Free Software Foundation.
On Debian systems, the complete text of the GNU General Public
License can be found in /usr/share/common-licenses/GPL.