UCARP(8)UCARP(8)NAMEucarp - Automatic IP failover
SYNOPSISucarp [ -i interface ] [ -s source address ] [ -v virtual id ] [ -p
password ] [ -P ] [ -n ] [ -a virt addr ] [ -h ] [ -b seconds ] [
-k skew ] [ -u script ] [ -d script ] [ -r ratio ] [ -z shutdown ]
[ -B daemonize ] [ -f facility ]
DESCRIPTIONucarp 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.
OPTIONSucarp supports the following command line options:
-i iface --interface=iface
The network interface to bind to.
-s srcip --srcip=srcip
The persistent source address, (real IP), associated with this
interface.
-v id --vhid=vhid
The id of the virtual server [1-255].
-p pass --pass=pass
The shared password, (this gets encrypted and is not sent in the
clear).
-P --preempt
Turn on preemptive failover. This causes an instance of ucarp to
take over master status right away.
-n --neutral
Do not run the downscript on startup when the initial state is
backup.
-a virtip --addr=virtip
The IP address of the virtual server.
-h --help
Display a brief summary of the command line options.
-b SECS --advbase=SECS
Interval in seconds that advertisements will occur, (defaults to
1 second).
-k NUM --advskew=NUM
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 argu‐
ment. This is typically a script used to bring down the virtual
interface, log the action, remove routes, etc.
-r NUM --deadratio=NUM
Ratio used by the backup to determine how long to wait for an
unresponsive master before considering it dead.
-z--shutdown
Use of this command causes the command specified by the -d argu‐
ment to be invoked when ucarp shuts down.
-B--daemonize
Causes ucarp to detach from the terminal and run in the back‐
ground as a daemon.
-f--facility
Set the syslog facility, defaults to daemon.
EXAMPLES
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.
ucarp-i eth0 -s 10.1.1.10 -v 10 -p secret -a 10.1.1.252 \\
--upscript=/etc/vip-up.sh --downscript=/etc/vip-down.sh -P
The backup might be configured something like this.
ucarp-i eth0 -s 10.1.1.11 -v 10 -p secret -a 10.1.1.252 \\
--upscript=/etc/vip-up.sh --downscript=/etc/vip-down.sh
A machine with a real IP of 192.168.1.19 is the preferred master for a
virtual IP of 10.1.12.7, broadcasts are sent every 5 seconds.
ucarp-b 5 -s 192.168.1.19 -v 27 -p badpass -a 10.1.12.7 \\
-u /etc/vip-up.sh -d /etc/vip-down.sh -z
The hot standby with an IP of 192.168.1.20 uses the following command,
(note the advskew of 50 putting it at a disadvantage and making the
first machine preferred).
ucarp-b 5 -k 50 -s 192.168.1.20 -v 27 -p badpass -a 10.1.12.7 \\
-u /etc/vip-up.sh -d /etc/vip-down.sh -z
AUTHORucarp was written by Frank Denis, <j@ucarp.org>.
This manual page was written by Eric Evans <<eevans@sym-link.com>> 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 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.
April 30, 2004 UCARP(8)
