KEEPALIVED.CONF(5)

NAME
keepalived.conf - configuration file for Keepalived

DESCRIPTION
keepalived.conf is the configuration file which describes all the Keepalived keywords. Keywords are placed in hierarchies of blocks and subblocks, each layer being delimited by '{' and '}' pairs.

Comments start with '#' or '!' to the end of the line and can start anywhere in a line.

The keyword 'include' allows inclusion of other configuration files from within the main configuration file.

PARAMETER SYNTAX
<BOOL> is one of on|off|true|false|yes|no

Conditional configuration and configuration id
Any configuration line starts with '@' is a conditional configuration line. The word immediately following (i.e. without any space) the '@' character is compared against the string specified with the -i command line option, and if they don't match, the configuration line is ignored.

The purpose of this is to allow a single configuration file to be used for multiple systems, where the only differences are likely to be the router_id, vrrp instance priorities, and possibly interface names.

For example:

 global_defs
 {
 @main router_id main_router
 @backup router_id backup_router
 }

If keepalived is invoked with -i main, then the router_id will be set to main_router, if invoked with -i backup, then backup_router, if not invoked with -i, or with -i anything else, then the router_id will not be set.

TOP HIERACHY

GLOBAL CONFIGURATION

VRRPD CONFIGURATION

LVS CONFIGURATION

GLOBAL CONFIGURATION
contains subblocks of Global definitions, Static routes, and Static rules

Global definitions

 global_defs # Block id
 {
 notification_email # To:
        {
        admin@example1.com
        ...
        }
 # From: from address that will be in the header (default keepalived@<local host name>)
 notification_email_from admin@example.com
 smtp_server 127.0.0.1 [<PORT>]
                        # IP address or domain name
                        # with optional port number (default 25)
 smtp_helo_name <HOST_NAME> # name to use in HELO messages
                        # defaults to local host name
 smtp_connect_timeout 30 # integer, seconds
 router_id my_hostname # string identifying the machine,
                        # (doesn't have to be hostname).
                        # default: local host name
 vrrp_mcast_group4 224.0.0.18 # optional, default 224.0.0.18
 vrrp_mcast_group6 ff02::12 # optional, default ff02::12
 default_interface p33p1.3 # sets the default interface for static addresses, default eth0
 lvs_sync_daemon <INTERFACE> <VRRP_INSTANCE> [id <SYNC_ID>] [maxlen <LEN>] [port <PORT>] [ttl <TTL>] [group <IP ADDR>]
                        # Binding interface, vrrp instance and optional
                        # syncid for lvs syncd
                        # syncid (0 to 255) for lvs syncd
                        # maxlen (1..65507) maximum packet length
                        # port (1..65535) UDP port number to use
                        # ttl (1..255)
                        # group - multicast group address (IPv4 or IPv6)
                        # NOTE: maxlen, port, ttl and group are only available on Linux 4.3 or later.
 lvs_flush # flush any existing LVS configuration at startup
 # delay for second set of gratuitous ARPs after transition to MASTER
 vrrp_garp_master_delay 10 # seconds, default 5, 0 for no second set
 # number of gratuitous ARP messages to send at a time after transition to MASTER
 vrrp_garp_master_repeat 1 # default 5
 # delay for second set of gratuitous ARPs after lower priority advert received when MASTER
 vrrp_garp_lower_prio_delay 10
 # number of gratuitous ARP messages to send at a time after lower priority advert received when MASTER
 vrrp_garp_lower_prio_repeat 1
 # minimum time interval for refreshing gratuitous ARPs while MASTER
 vrrp_garp_master_refresh 60 # secs, default 0 (no refreshing)
 # number of gratuitous ARP messages to send at a time while MASTER
 vrrp_garp_master_refresh_repeat 2 # default 1
 # Delay in ms between gratuitous ARP messages sent on an interface
 vrrp_garp_interval 0.001 # decimal, seconds (resolution usecs). Default 0.
 # Delay in ms between unsolicited NA messages sent on an interface
 vrrp_gna_interval 0.000001 # decimal, seconds (resolution usecs). Default 0.
 # If a lower priority advert is received, don't send another advert. This causes
 # adherence to the RFCs. Defaults to false, unless strict_mode is set.
 vrrp_lower_prio_no_advert [<BOOL>]
 # Set the default VRRP version to use
 vrrp_version <2 or 3> # default version 2
 # Specify the iptables chain for ensuring a version 3 instance
 # doesn't respond on addresses that it doesn't own.
 # Note: it is necessary for the specified chain to exist in
 # the iptables and/or ip6tables configuration, and for the chain
 # to be called from an appropriate point in the iptables configuration.
 # It will probably be necessary to have this filtering after accepting
 # any ESTABLISHED,RELATED packets, because IPv4 might select the VIP as
 # the source address for outgoing connections.
 vrrp_iptables keepalived # default INPUT
 # or for outbound filtering as well
 # Note, outbound filtering won't work with IPv4, since the VIP can be selected as the source address
 # for an outgoing connection. With IPv6 this is unlikely since the addresses are deprecated.
 vrrp_iptables keepalived_in keepalived_out
 # or to not add any iptables rules:
 vrrp_iptables
 # Keepalived may have the option to use ipsets in conjunction with iptables.
 # If so, then the ipset names can be specified, defaults as below.
 # If no names are specified, ipsets will not be used, otherwise any omitted
 # names will be constructed by adding "_if" and/or "6" to previously specified
 # names.
 vrrp_ipset [keepalived [keepalived6 [keepalived_if6]]]
 # The following enables checking that when in unicast mode, the source
 # address of a VRRP packet is one of our unicast peers.
 vrrp_check_unicast_src
 # Checking all the addresses in a received VRRP advert can be time consuming.
 # Setting this flag means the check won't be carried out if the advert is
 # from the same master router as the previous advert received.
 vrrp_skip_check_adv_addr # Default - don't skip
 # Enforce strict VRRP protocol compliance. This will prohibit:
 # 0 VIPs
 # unicast peers
 # IPv6 addresses in VRRP version 2
 vrrp_strict
 # The following 4 options can be used if vrrp or checker processes
 # are timing out. This can be seen by a backup vrrp instance becoming
 # master even when the master is still running because the master or
 # backup system is too busy to process vrrp packets.
 vrrp_priority <-20 to 19> # Set the vrrp child process priority
                        # Negative values increase priority.
 checker_priority <-20 to 19> # Set the checker child process priority
 vrrp_no_swap # Set the vrrp child process non swappable
 checker_no_swap # Set the checker child process non swappable
 # If Keepalived has been build with SNMP support, the following keywords are available
 # Note: Keepalived, checker and RFC support can be individually enabled/disabled
 snmp_socket udp:1.2.3.4:705 # specify socket to use for connecting to SNMP master agent (default unix:/var/agentx/master)
                        # unless using a network namespace, when the default is udp:localhost:705
 enable_snmp_keepalived # enable SNMP handling of vrrp element of KEEPALIVED MIB
 enable_snmp_checker # enable SNMP handling of checker element of KEEPALIVED MIB
 enable_snmp_rfc # enable SNMP handling of RFC2787 and RFC6527 VRRP MIBs
 enable_snmp_rfcv2 # enable SNMP handling of RFC2787 VRRP MIB
 enable_snmp_rfcv3 # enable SNMP handling of RFC6527 VRRP MIB
 enable_traps # enable SNMP traps
 # If Keepalived has been build with DBus support, the following keyword is available
 enable_dbus # enable the DBus interface
 # Specify the default username/groupname to run scripts under.
 # If this option is not specified, the user defaults to keepalived_script
 # if that user exists, otherwise root.
 script_user username [groupname] # If groupname is not specified, it defaults to the user's group
 enable_script_security # Don't run scripts configured to be run as root if any part of the path
                        # is writable by a non-root user.
 }
 # For running keepalived in a separate network namespace
 net_namespace NAME # Set the network namespace to run in
                        # The directory /var/run/keepalived will be created as an unshared mount point,
                        # for example for pid files.
                        # syslog entries will have _NAME appended to the ident.
                        # Note: the namespace cannot be changed on a configuration reload
 namespace_with_ipsets # ipsets wasn't network namespace aware until Linux 3.13, and so if running with
                        # an earlier version of the kernel, by default use of ipsets is disabled if using
                        # a namespace and vrrp_ipsets has not been specified. This options overrides the
                        # default and allows ipsets to be used with a namespace on kernels prior to 3.13.
 instance NAME # If multiple instances of keepalived are run in the same namespace, this will
                        # create pid files with NAME as part of the file names, in /var/run/keepalived.
                        # Note: the instance name cannot be changed on a configuration reload
 use_pid_dir          # Create pid files in /var/run/keepalived
 linkbeat_use_polling # Poll to detect media link failure otherwise attempt to use ETHTOOL or MII interface

Static routes/addresses/rules

Keepalived can configure static addresses, routes, and rules. These addresses are NOT moved by vrrpd, they stay on the machine. If you already have IPs and routes on your machines and your machines can ping each other, you don't need this section. The syntax for rules and routes is that same as for ip rule add/ip route add.

The syntax is the same for virtual addresses and virtual routes. If no dev element is specified, it defaults to default_interface (default eth0).

 static_ipaddress
 {
 192.168.1.1/24 dev eth0 scope global
 ...
 }

 static_routes
 {
 192.168.2.0/24 via 192.168.1.100 dev eth0
 192.168.100.0/24 table 6909 nexthop via 192.168.101.1 dev wlan0 onlink weight 1 nexthop via 192.168.101.2 dev wlan0 onlink weight 2
 192.168.200.0/24 dev p33p1.2 table 6909 tos 0x04 protocol bird scope link priority 12 mtu 1000 hoplimit 100 advmss 101 rtt 102 rttvar 103 reordering 104 window 105 cwnd 106 ssthresh lock 107 realms PQA/0x14 rto_min 108 initcwnd 109 initrwnd 110 features ecn
 2001:470:69e9:1:2::4 dev p33p1.2 table 6909 tos 0x04 protocol bird scope link priority 12 mtu 1000 hoplimit 100 advmss 101 rtt 102 rttvar 103 reordering 104 window 105 cwnd 106 ssthresh lock 107 rto_min 108 initcwnd 109 initrwnd 110 features ecn
 ...
 }

 static_rules
 {
 from 192.168.2.0/24 table 1
 to 192.168.2.0/24 table 1
 from 192.168.28.0/24 to 192.168.29.0/26 table small iif p33p1 oif wlan0 tos 22 fwmark 24/12 preference 39 realms 30/20 goto 40
 to 1:2:3:4:5:6:7:0/112 from 7:6:5:4:3:2::/96 table 6908
 ...
 }

VRRPD CONFIGURATION
contains subblocks of VRRP script(s), VRRP synchronization group(s), VRRP gratuitous ARP and unsolicited neighbour advert delay group(s) and VRRP instance(s)

VRRP script(s)

 # Adds a script to be executed periodically. Its exit code will be
 # recorded for all VRRP instances which are monitoring it.
 vrrp_script <SCRIPT_NAME> {
    script <STRING>|<QUOTED-STRING> # path of the script to execute
    interval <INTEGER> # seconds between script invocations, default 1 second
    timeout <INTEGER> # seconds after which script is considered to have failed
    weight <INTEGER:-254..254> # adjust priority by this weight, default 0
    rise <INTEGER> # required number of successes for OK transition
    fall <INTEGER> # required number of successes for KO transition
    user USERNAME [GROUPNAME] # user/group names to run script under
                        # group default to group of user
    init_fail # assume script initially is in failed state
 }

VRRP synchronization group(s)

 #string, name of group of IPs that failover together
 vrrp_sync_group VG_1 {
    group {
      inside_network # name of the vrrp_instance (see below)
      outside_network # One for each movable IP
      ...
    }
    # notify scripts and alerts are optional
    #
    # filenames of scripts to run on transitions
    # can be unquoted (if just filename)
    # or quoted (if it has parameters)
    # The username and groupname specify the user and group
    # under which the scripts should be run. If username is
    # specified, the group defaults to the group of the user.
    # If username is not specified, they default to the
    # global script_user and script_group
    # to MASTER transition
    notify_master /path/to_master.sh [username [groupname]]
    # to BACKUP transition
    notify_backup /path/to_backup.sh [username [groupname]]
    # FAULT transition
    notify_fault "/path/fault.sh VG_1" [username [groupname]]
    # for ANY state transition.
    # "notify" script is called AFTER the
    # notify_* script(s) and is executed
    # with 4 arguments provided by Keepalived
    # (so don't include parameters in the notify line).
    # arguments
    # $1 = "GROUP"|"INSTANCE"
    # $2 = name of the group or instance
    # $3 = target state of transition
    # ("MASTER"|"BACKUP"|"FAULT")
    # $4 = priority value
    notify /path/notify.sh [username [groupname]]
    # Send email notification during state transition,
    # using addresses in global_defs above.
    smtp_alert
    global_tracking # All VRRP share the same tracking config
 }

VRRP gratuitous ARP and unsolicited neighbour advert delay group(s)

specifies the setting of delays between sending gratuitous ARPs and unsolicited neighbour advertisements. This is intended for when an upstream switch is unable to handle being flooded with ARPs/NAs. Use interface when the limits apply on the single physical interface. Use interfaces when a group of interfaces are linked to the same switch and the limits apply to the switch as a whole. If the global vrrp_garp_interval and/or vrrp_gna_interval are set, any interfaces that aren't specified in a garp_group will inherit the global settings.

garp_group {
    # Sets the interval between Gratuitous ARP (in seconds, resolution microseconds)
    garp_interval <DECIMAL>
    # Sets the default interval between unsolicited NA (in seconds, resolution microseconds)
    gna_interval <DECIMAL>
    # The physical interface to which the intervals apply
    interface <STRING>
    # A list of interfaces accross which the delays are aggregated.
    interfaces {
        <STRING>
        <STRING>
        ...
        }
    }

VRRP instance(s)

describes the movable IP for each instance of a group in vrrp_sync_group. Here are described two IPs (on inside_network and on outside_network), on machine "my_hostname", which belong to the group VG_1 and which will transition together on any state change.

 #You will need to write another block for outside_network.
 vrrp_instance inside_network {
    # Initial state, MASTER|BACKUP
    # As soon as the other machine(s) come up,
    # an election will be held and the machine
    # with the highest priority will become MASTER.
    # So the entry here doesn't matter a whole lot.
    state MASTER
    # interface for inside_network, bound by vrrp
    interface eth0
    # Use VRRP Virtual MAC.
    use_vmac [<VMAC_INTERFACE>]
    # Send/Recv VRRP messages from base interface instead of
    # VMAC interface
    vmac_xmit_base
    native_ipv6 # force instance to use IPv6 (when mixed IPv4 and IPv6 config).
    # Ignore VRRP interface faults (default unset)
    dont_track_primary
    # optional, monitor these as well.
    # go to FAULT state if any of these go down.
    track_interface {
      eth0
      eth1
      eth2 weight <-254..254>
      ...
    }
    # add a tracking script to the interface (<SCRIPT_NAME> is the name of the vrrp_script entry)
    track_script {
        <SCRIPT_NAME>
        <SCRIPT_NAME> weight <-254..254>
    }
    # default IP for binding vrrpd is the primary IP
    # on interface. If you want to hide the location of vrrpd,
    # use this IP as src_addr for multicast or unicast vrrp
    # packets. (since it's multicast, vrrpd will get the reply
    # packet no matter what src_addr is used).
    # optional
    mcast_src_ip <IPADDR>
    unicast_src_ip <IPADDR>
    version <2 or 3> # VRRP version to run on interface
                        # default is global parameter vrrp_version.
    # Do not send VRRP adverts over a VRRP multicast group.
    # Instead it sends adverts to the following list of
    # ip addresses using unicast. It can be cool to use
    # the VRRP FSM and features in a networking
    # environment where multicast is not supported!
    # IP addresses specified can be IPv4 as well as IPv6.
    unicast_peer {
      <IPADDR>
      ...
    }
    # interface specific settings, same as global parameters; default to global parameters
    garp_master_delay 10
    garp_master_repeat 1
    garp_lower_prio_delay 10
    garp_lower_prio_repeat 1
    garp_master_refresh 60
    garp_master_refresh_repeat 2
    garp_interval 100
    gna_interval 100
    lower_prio_no_advert [<BOOL>]
    # arbitrary unique number from 0 to 255
    # used to differentiate multiple instances of vrrpd
    # running on the same NIC (and hence same socket).
    virtual_router_id 51
    # for electing MASTER, highest priority wins.
    # to be MASTER, make this 50 more than on other machines.
    priority 100
    # VRRP Advert interval in seconds (e.g. 0.92) (use default)
    advert_int 1
    # Note: authentication was removed from the VRRPv2 specification by RFC3768 in 2004.
    # Use of this option is non-compliant and can cause problems; avoid using if possible,
    # except when using unicast, where it can be helpful.
    authentication { # Authentication block
        # PASS||AH
        # PASS - Simple password (suggested)
        # AH - IPSEC (not recommended))
        auth_type PASS
        # Password for accessing vrrpd.
        # should be the same on all machines.
        # Only the first eight (8) characters are used.
        auth_pass 1234
    }
    #addresses add|del on change to MASTER, to BACKUP.
    #With the same entries on other machines,
    #the opposite transition will be occurring.
    virtual_ipaddress {
        <IPADDR>/<MASK> brd <IPADDR> dev <STRING> scope <SCOPE> label <LABEL>
        192.168.200.17/24 dev eth1
        192.168.200.18/24 dev eth2 label eth2:1
    }
    #VRRP IP excluded from VRRP
    #optional.
    #For cases with large numbers (eg 200) of IPs
    #on the same interface. To decrease the number
    #of packets sent in adverts, you can exclude
    #most IPs from adverts.
    #The IPs are add|del as for virtual_ipaddress.
    # Can also be used if you want to be able to add
    # a mixture of IPv4 and IPv6 addresses, since all
    # addresses in virtual_ipaddress must be of the
    # same family.
    virtual_ipaddress_excluded {
     <IPADDR>/<MASK> brd <IPADDR> dev <STRING> scope <SCOPE>
     <IPADDR>/<MASK> brd <IPADDR> dev <STRING> scope <SCOPE>
        ...
    }
    # Set the promote_secondaries flag on the interface to stop other
    # addresses in the same CIDR being removed when 1 of them is removed
    # For example if 10.1.1.2/24 and 10.1.1.3/24 are both configured on an
    # interface, and one is removed, unless promote_secondaries is set on
    # the interface the other address will also be removed.
    prompte_secondaries
    # routes add|del when changing to MASTER, to BACKUP.
    # See static_routes for more details
    virtual_routes {
        # src <IPADDR> [to] <IPADDR>/<MASK> via|gw <IPADDR> [or <IPADDR>] dev <STRING> scope <SCOPE> table <TABLE>
        src 192.168.100.1 to 192.168.109.0/24 via 192.168.200.254 dev eth1
        192.168.110.0/24 via 192.168.200.254 dev eth1
        192.168.111.0/24 dev eth2
        192.168.112.0/24 via 192.168.100.254
        192.168.113.0/24 via 192.168.200.254 or 192.168.100.254 dev eth1
        blackhole 192.168.114.0/24
        0.0.0.0/0 gw 192.168.0.1 table 100 # To set a default gateway into table 100.
    }
    # rules add|del when changing to MASTER, to BACKUP
    # See static_rules for more details
    virtual_rules {
        from 192.168.2.0/24 table 1
        to 192.168.2.0/24 table 1
    }
    # VRRPv3 has an Accept Mode to allow the virtual router when not the address owner to
    # receive packets addressed to a VIP. This is the default setting unless strict mode is set.
    # As an extension, this also works for VRRPv2 (RFC 3768 doesn't define an accept mode).
    accept    # Accept packets to non address-owner
    no_accept    # Drop packets to non address-owner.
    # VRRP will normally preempt a lower priority
    # machine when a higher priority machine comes
    # online. "nopreempt" allows the lower priority
    # machine to maintain the master role, even when
    # a higher priority machine comes back online.
    # NOTE: For this to work, the initial state of this
    # entry must be BACKUP.
    nopreempt
    preempt # for backwards compatibility
    # See description of global vrrp_skip_check_adv_addr, which
    # sets the default value. Defaults to vrrp_skip_check_adv_addr
    skip_check_adv_addr [on|off|true|false|yes|no] # Default on if no word specified
    # See description of global vrrp_strict
    # If vrrp_strict is not specified, it takes the value of vrrp_strict
    # If strict_mode without a parameter is specified, it defaults to on
    strict_mode [on|off|true|false|yes|no]
    # Seconds after startup or seeing a lower priority master until preemption
    # (if not disabled by "nopreempt").
    # Range: 0 (default) to 1000
    # NOTE: For this to work, the initial state of this
    # entry must be BACKUP.
    preempt_delay 300 # waits 5 minutes
    # Debug level, not implemented yet.
    debug <LEVEL> # LEVEL is a number in the range 0 to 4
    # notify scripts, alert as above
    notify_master <STRING>|<QUOTED-STRING> [username [groupname]]
    notify_backup <STRING>|<QUOTED-STRING> [username [groupname]]
    notify_fault <STRING>|<QUOTED-STRING> [username [groupname]]
    notify_stop <STRING>|<QUOTED-STRING> [username [groupname]] # executed when stopping vrrp
    notify <STRING>|<QUOTED-STRING> [username [groupname]]
    smtp_alert
 }
 # Parameters used for SSL_GET check.
 # If none of the parameters are specified, the SSL context will be auto generated.
 SSL {
    password <STRING> # password
    ca <STRING> # ca file
    certificate <STRING> # certificate file
    key <STRING> # key file
 }

LVS CONFIGURATION
contains subblocks of Virtual server group(s) and Virtual server(s)

The subblocks contain arguments for ipvsadm(8). Knowledge of ipvsadm(8) will be helpful here.

Virtual server group(s)

 # optional
 # this groups allows a service on a real_server
 # to belong to multiple virtual services
 # and to only be health checked once.
 # Only for very large LVSs.
 virtual_server_group <STRING> {
        #VIP port
        <IPADDR> <PORT>
        <IPADDR> <PORT>
        ...
        #
        # <IPADDR RANGE> has the form
        # XXX.YYY.ZZZ.WWW-VVV eg 192.168.200.1-10
        # range includes both .1 and .10 address
        <IPADDR RANGE> <PORT># VIP range VPORT
        <IPADDR RANGE> <PORT>
        ...
        fwmark <INT> # fwmark
        fwmark <INT>
        ... }

Virtual server(s)

A virtual_server can be a declaration of one of

vip vport (IPADDR PORT pair)

fwmark <INT>

(virtual server) group <STRING>
        #setup service
        virtual_server IP port |
        virtual_server fwmark int |
        virtual_server group string
        {
        # delay timer for service polling
        delay_loop <INT>
        # LVS scheduler
        lb_algo rr|wrr|lc|wlc|lblc|sh|dh

        # Enable hashed entry
        hashed
        # Enable flag-1 for scheduler (-b flag-1 in ipvsadm)
        flag-1
        # Enable flag-2 for scheduler (-b flag-2 in ipvsadm)
        flag-2
        # Enable flag-3 for scheduler (-b flag-3 in ipvsadm)
        flag-3
        # Enable sh-port for sh scheduler (-b sh-port in ipvsadm)
        sh-port
        # Enable sh-fallback for sh scheduler (-b sh-fallback in ipvsadm)
        sh-fallback
        # Enable One-Packet-Scheduling for UDP (-O in ipvsadm)
        ops
        # LVS forwarding method
        lb_kind NAT|DR|TUN
        # LVS persistence engine name
        persistence_engine <STRING>
        # LVS persistence timeout in seconds, default 6 minutes
        persistence_timeout [<INT>]
        # LVS granularity mask (-M in ipvsadm)
        persistence_granularity <NETMASK>
        # L4 protocol
        protocol TCP|UDP|SCTP
        # If VS IP address is not set,
        # suspend healthchecker's activity
        ha_suspend
        lvs_sched # synonym for lb_algo
        lvs_method # synonym for lb_kind
        # VirtualHost string for HTTP_GET or SSL_GET
        # eg virtualhost www.firewall.loc
        virtualhost <STRING>
        # On daemon startup assume that all RSs are down
        # and healthchecks failed. This helps to prevent
        # false positives on startup. Alpha mode is
        # disabled by default.
        alpha
        # On daemon shutdown consider quorum and RS
        # down notifiers for execution, where appropriate.
        # Omega mode is disabled by default.
        omega
        # Minimum total weight of all live servers in
        # the pool necessary to operate VS with no
        # quality regression. Defaults to 1.
        quorum <INT>
        # Tolerate this much weight units compared to the
        # nominal quorum, when considering quorum gain
        # or loss. A flap dampener. Defaults to 0.
        hysteresis <INT>
        # Script to execute when quorum is gained.
        quorum_up <STRING>|<QUOTED-STRING>
        # Script to execute when quorum is lost.
        quorum_down <STRING>|<QUOTED-STRING>
        # IP family for a fwmark service (optional)
        ip_family inet|inet6
        # setup realserver(s)
        # RS to add when all realservers are down
        sorry_server <IPADDR> <PORT>
        # applies inhibit_on_failure behaviour to the
        # preceding sorry_server directive
        sorry_server_inhibit
        # one entry for each realserver
        real_server <IPADDR> <PORT>
           {
               # relative weight to use, default: 1
               weight <INT>
               # Set weight to 0 when healthchecker detects failure
               inhibit_on_failure
               # Script to execute when healthchecker
               # considers service as up.
               notify_up <STRING>|<QUOTED-STRING>
               # Script to execute when healthchecker
               # considers service as down.
               notify_down <STRING>|<QUOTED-STRING>
               uthreshold <INTEGER> # maximum number of connections to server
               lthreshold <INTEGER> # minimum number of connections to server
               # pick one healthchecker
               # HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|DNS_CHECK|MISC_CHECK
               # HTTP and SSL healthcheckers
               HTTP_GET|SSL_GET
               {
                   # An url to test
                   # can have multiple entries here
                   url {
                     #eg path / , or path /mrtg2/
                     path <STRING>
                     # healthcheck needs status_code
                     # or status_code and digest
                     # Digest computed with genhash
                     # eg digest 9b3a0c85a887a256d6939da88aabd8cd
                     digest <STRING>
                     # status code returned in the HTTP header
                     # eg status_code 200. Default is any 2xx value
                     status_code <INT>
                   }
                   # number of get retries
                   nb_get_retry <INT>
                   # delay before retry
                   delay_before_retry <INT>
                   # ======== generic connection options
                   # Optional IP address to connect to.
                   # The default is the realserver IP
                   connect_ip <IP ADDRESS>
                   # Optional port to connect to
                   # The default is the realserver port
                   connect_port <PORT>
                   # Optional interface to use to
                   # originate the connection
                   bindto <IP ADDRESS>
                   # Optional source port to
                   # originate the connection from
                   bind_port <PORT>
                   # Optional connection timeout in seconds.
                   # The default is 5 seconds
                   connect_timeout <INTEGER>
                   # Optional fwmark to mark all outgoing
                   # checker packets with
                   fwmark <INTEGER>
                   # Optional random delay to start the initial check
                   # for maximum N seconds.
                   # Useful to scatter multiple simultaneous
                   # checks to the same RS. Enabled by default, with
                   # the maximum at delay_loop. Specify 0 to disable
                   warmup <INT>
               } #HTTP_GET|SSL_GET
               # TCP healthchecker
               TCP_CHECK
               {
                   # ======== generic connection options
                   # Optional IP address to connect to.
                   # The default is the realserver IP
                   connect_ip <IP ADDRESS>
                   # Optional port to connect to
                   # The default is the realserver port
                   connect_port <PORT>
                   # Optional interface to use to
                   # originate the connection
                   bindto <IP ADDRESS>
                   # Optional source port to
                   # originate the connection from
                   bind_port <PORT>
                   # Optional connection timeout in seconds.
                   # The default is 5 seconds
                   connect_timeout <INTEGER>
                   # Optional fwmark to mark all outgoing
                   # checker packets with
                   fwmark <INTEGER>
                   # Optional random delay to start the initial check
                   # for maximum N seconds.
                   # Useful to scatter multiple simultaneous
                   # checks to the same RS. Enabled by default, with
                   # the maximum at delay_loop. Specify 0 to disable
                   warmup <INT>
                   # Retry count to make additional checks if check
                   # of an alive server fails. Default: 1
                   retry <INT>
                   # Delay in seconds before retrying. Default: 1
                   delay_before_retry <INT>
               } #TCP_CHECK
               # SMTP healthchecker
               SMTP_CHECK
               {
                   # ======== generic connection options
                   # Optional IP address to connect to.
                   # The default is the realserver IP
                   connect_ip <IP ADDRESS>
                   # Optional port to connect to
                   # the default is port 25
                   connect_port <PORT>
                   # Optional interface to use to
                   # originate the connection
                   bindto <IP ADDRESS>
                   # Optional source port to
                   # originate the connection from
                   bind_port <PORT>
                   # Optional per-host connection timeout.
                   # Default is outer-scope connect_timeout
                   connect_timeout <INTEGER>
                   # Optional fwmark to mark all outgoing
                   # checker packets with
                   fwmark <INTEGER>
                   # An optional host interface to check.
                   # If no host directives are present, only
                   # the IP address of the realserver will
                   # be checked.
                   host {
                     # ======== generic connection options
                     # Optional IP address to connect to.
                     # The default is the realserver IP
                     connect_ip <IP ADDRESS>
                     # Optional port to connect to
                     # the default is port 25
                     connect_port <PORT>
                     # Optional interface to use to
                     # originate the connection
                     bindto <IP ADDRESS>
                     # Optional source port to
                     # originate the connection from
                     bind_port <PORT>
                     # Optional per-host connection timeout.
                     # Default is outer-scope connect_timeout
                     connect_timeout <INTEGER>
                     # Optional fwmark to mark all outgoing
                     # checker packets with
                     fwmark <INTEGER>
                  }
                  # Number of times to retry a failed check
                  retry <INTEGER>
                  # Delay in seconds before retrying
                  delay_before_retry <INTEGER>
                  # Optional string to use for the SMTP HELO request
                  helo_name <STRING>|<QUOTED-STRING>
                  # Optional random delay to start the initial check
                  # for maximum N seconds.
                  # Useful to scatter multiple simultaneous
                  # checks to the same RS. Enabled by default, with
                  # the maximum at delay_loop. Specify 0 to disable
                  warmup <INT>
               } #SMTP_CHECK
               # DNS healthchecker
               DNS_CHECK
               {
                   # ======== generic connection options
                   # Optional IP address to connect to.
                   # The default is the realserver IP
                   connect_ip <IP ADDRESS>
                   # Optional port to connect to
                   # The default is the realserver port
                   connect_port <PORT>
                   # Optional interface to use to
                   # originate the connection
                   bindto <IP ADDRESS>
                   # Optional source port to
                   # originate the connection from
                   bind_port <PORT>
                   # Optional connection timeout in seconds.
                   # The default is 5 seconds
                   connect_timeout <INTEGER>
                   # Optional fwmark to mark all outgoing
                   # checker packets with
                   fwmark <INTEGER>
                   # Number of times to retry a failed check
                   # The default is 3 times.
                   retry <INTEGER>
                   # DNS query type
                   # A|NS|CNAME|SOA|MX|TXT|AAAA
                   # The default is SOA
                   type <STRING>
                   # Domain name to use for the DNS query
                   # The default is . (dot)
                   name <STRING>
               }
               # MISC healthchecker, run a program
               MISC_CHECK
               {
                   # External script or program
                   misc_path <STRING>|<QUOTED-STRING>
                   # Script execution timeout
                   misc_timeout <INT>
                   # Optional random delay to start the initial check
                   # for maximum N seconds.
                   # Useful to scatter multiple simultaneous
                   # checks to the same RS. Enabled by default, with
                   # the maximum at delay_loop. Specify 0 to disable
                   warmup <INT>
                   # If set, the exit code from healthchecker is used
                   # to dynamically adjust the weight as follows:
                   # exit status 0: svc check success, weight
                   # unchanged.
                   # exit status 1: svc check failed.
                   # exit status 2-255: svc check success, weight
                   # changed to 2 less than exit status.
                   # (for example: exit status of 255 would set
                   # weight to 253)
                   misc_dynamic
                   # Specify the username/groupname that the script should
                   # be run under.
                   # If GROUPNAME is not specified, the group of the user
                   # is used
                   user USERNAME [GROUPNAME]
               }
           } # realserver defn
        } # virtual service

AUTHOR
Joseph Mack.
Information derived from doc/keepalived.conf.SYNOPSIS, doc/samples/keepalived.conf.* and Changelog by Alexandre Cassen for keepalived-1.1.4, and from HOWTOs by Adam Fletcher and Vince Worthington.

SEE ALSO
ipvsadm(8), ip --help.