ucarp - automatic IP failover

       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).

ucarp-1.5.2+git20192404.1a9aaf7                    08 Jan 2023                                          ucarp(8)

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.

       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

ucarp - automatic IP failover

-iINTERFACE,--interface=INTERFACE
              The network interface to bind to.

       -sIPADDRESS,--srcip=IPADDRESS
              The persistent source address, (real IP), associated with this interface.

       -mIPADDRESS,--mcast=IPADDRESS
              Multicast group IP address (default 224.0.0.18).

       -vVHID,--vhid=VHID
              The id of the virtual server [1-255].

       -pPASSWORD,--pass=PASSWORD
              The shared password, (this gets encrypted and is not sent in the clear).

       -oPASSFILE,--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.

       -aIPADDRESS,--addr=IPADDRESS
              The IP address of the virtual server.

       -h,--help
              Display a brief summary of the command line options.

       -bSECONDS,--advbase=SECONDS
              Interval in seconds that advertisements will occur, (defaults to 1 second).

       -kSKEW,--advskew=SKEW
              Advertisement skew [1-255], (defaults to 0).

       -uCOMMAND--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.

       -dCOMMAND,--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.

       -rRATIO,--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.

       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.

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, --xparamPARAM] [-S, --ignoreifstate]
             [-M, --nomcast]