NAME
  ucarp - automatic IP failover

SYNOPSIS
  ucarp [-i, --interface=INTERFACE]  [-s, --srcip=IPADDRESS]
        [-m, --mcast=<ip>] [-v, --vhid=VHID]  [-p, --pass=PASSWORD]
        [-o, --passfile=PASSFILE] [-P, --preempt] [-n, --neutral]
        [-a, --addr=IPADDR] [-h, --help] [-b, --advbase=SECS]
        [-k, --advskew=SKEW]  [-u, --upscript=SCRIPT] [-d, --downscript=SCRIPT]
        [-r, --deadratio=RATIO] [-D, --debug] [-z, --shutdown] [-B, --daemonize]
        [-f, --facility=FACILITY] [-x, --xparam PARAM] [-S, --ignoreifstate]
        [-M, --nomcast]

DESCRIPTION
  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.

  Warning: Maximum length of the password used must be 20 characters.

OPTIONS
   -i INTERFACE, --interface=INTERFACE                 The network interface to bind to.
   -s IPADDRESS, --srcip=IPADDRESS                     The persistent source address, (real IP), associated with this interface.
   -m IPADDRESS, --mcast=IPADDRESS                     Multicast group IP address (default 224.0.0.18).
   -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 clear).
   -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.
   -P, --preempt                                       Turn on preemptive failover. This causes an instance of ucarp to assume master status right immediately.
   -n, --neutral                                       Do not run the downscript on startup when the initial state is backup.
   -a IPADDRESS, --addr=IPADDRESS                      The IP address of the virtual server.
   -h, --help                                          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 upthe 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.
   -D, --debug                                         Enable debug output.
   -z, --shutdown                                      Use of this command causes the command specified by the -d argument to be invoked when ucarp shuts down.
   -B, --daemonize                                     Causes ucarp to detach from the terminal and run in the background as a daemon.
   -f, --facility=FACILITY                             Set the syslog facility, defaults to daemon.
   -x, --xparam=PARAMETER                    Specify an extra parameter to be supplied to the up/down scripts.
   -S, --ignoreifstate                                 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).
   -M, --nomcast                                       Use broadcast instead of multicast advertisements.

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

SIGNALS
 Sending the ucarp process a SIGUSR1 will have it log a status line to syslog, eg "Sep 13 12:59:56 localhost ucarp[2654]: [INFO] MASTER on eth0 id 1" or "Sep 13 13:00:25 localhost ucarp[2644]: [INFO] BACKUP on eth0 id 1"

 Sending the ucarp process a SIGUSR2 will cause it to demote itself from master to backup, pause 3 seconds, then proceed as usual to listen for other masters, and promote itself if necessary. This could be useful if you wish another node to take over master.

AUTHOR
  Written by Frank Denis <j@pureftpd.org>.

  This manual page was written by Guilherme de Paula Xavier Segundo
 <guilherme.lnx@gmail.com> and Eric Evans <eevans@debian.org> for the Debian project (but may be used by others).
