Provided by: ucarp_1.1-2_i386 bug


       ucarp — Automatic IP failover


       ucarp  [-i  interface]   [-s  source  address]   [-v  virtual  id]  [-p
       password]  [-P]  [-a virt addr]  [-h]  [-b  seconds]   [-k  skew]   [-u
       script]   [-d  script]   [-r ratio]  [-z shutdown]  [-B daemonize]  [-f


       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


       ucarp 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.

       -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  argument.  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
                 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
                 Set the syslog facility, defaults to daemon.


       A host with a real IP of configured to be  the  master  in  a
       preemptive configuration with a virtual IP of

           ucarp -i eth0 -s -v 10 -p secret -a \
           --upscript=/etc/ --downscript=/etc/ -P

       The backup might be configured something like this.

           ucarp -i eth0 -s -v 10 -p secret -a \
           --upscript=/etc/ --downscript=/etc/

       A  machine with a real IP of is the preferred master for a
       virtual IP of, broadcasts are sent every 5 seconds.

           ucarp -b 5 -s -v 27 -p badpass -a \
           -u /etc/ -d /etc/ -z

       The hot standby with an IP of 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 -v 27 -p badpass -a \
           -u /etc/ -d /etc/ -z


       ucarp was written by Frank Denis, <>.

       This manual page was written by Eric  Evans  <>  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.