====== Протокол CARP ======

  * [[https://ru.wikipedia.org/wiki/VRRP|VRRP]]
  * [[https://ru.wikipedia.org/wiki/CARP|CARP]]
  * [[Сервис NTP]]

===== Debian/Ubuntu =====

  * [[https://serverfault.com/questions/298776/ucarp-promote-slave-to-master|ucarp: promote slave to master]]
  * [[https://askubuntu.com/questions/1149275/using-netplan-with-ucarp|Using netplan with ucarp]] + systemd
==== Установка ====
<code>
root@nodeN:~# apt install ucarp
</code>

==== Настройка ====
<code>
root@nodeN:~# less /usr/share/doc/ucarp/README.Debian

root@nodeN:~# less /etc/network/if-up.d/ucarp

root@nodeN:~# cat /etc/network/interfaces
</code><code>
...
auto eth0
iface eth0 inet static
        address 192.168.X.N
        netmask 255.255.255.0

        ucarp-vid 1
        ucarp-vip 192.168.X.254
        ucarp-password secret

iface eth0:ucarp inet static
        address 192.168.X.254
        netmask 255.255.255.255
...
</code><code>
root@nodeN:~# less /usr/share/ucarp/vip-up
</code><code>
#!/bin/sh

/sbin/ifup $1:ucarp
</code><code>
root@nodeN:~# less /usr/share/ucarp/vip-down
</code><code>
#!/bin/sh

/sbin/ifdown $1:ucarp
</code>

==== Запуск ====
<code>
root@nodeN:~# ifdown --force eth0

root@nodeN:~# ifup eth0
</code>

==== Проверка ====

  * [[Сигналы#Отправка сигнала]]

<code>
root@nodeN:~# ps ax | grep carp

root@nodeN:~# ifconfig eth0:ucarp

root@nodeN:~# pkill -USR1 ucarp

root@nodeN:~# killall -USR1 ucarp

root@nodeN:~# grep carp /var/log/syslog
</code>

==== Смена ролей узлов ====
<code>
wincmd:\> arp -a

masternode# pkill -USR2 ucarp

masternode# killall -USR2 ucarp

wincmd:\> arp -a
</code>


===== FreeBSD (user land) =====

==== Установка ====
<code>
[nodeN:~] # pkg install ucarp
</code>

==== Настройка ====
<code>
[nodeN:~] # less /usr/local/etc/rc.d/ucarp

[nodeN:~] # cat /etc/rc.conf
</code><code>
...
ucarp_src="192.168.X.N"
ucarp_enable="YES"
ucarp_vhid="1"
ucarp_if="em0"
ucarp_addr="192.168.X.254"
ucarp_pass="secret"
ucarp_upscript="/usr/local/sbin/ucarp-up"
ucarp_downscript="/usr/local/sbin/ucarp-down"
</code><code>
[nodeN:~] # cat /usr/local/sbin/ucarp-up
</code><code>
#!/bin/sh
...
/sbin/ifconfig "$1" alias "$2" netmask 255.255.255.255
</code><code>
[nodeN:~] # cat /usr/local/sbin/ucarp-down
</code><code>
#!/bin/sh
...
/sbin/ifconfig "$1" -alias "$2"
...
</code><code>
[nodeN:~] # service ucarp start
</code>

===== Дополнительные материалы =====

  * [[http://serverfault.com/questions/179263/multiple-ucarp-vips-on-single-interface-with-debian-ubuntu|Multiple UCARP VIPs on single Interface with Debian/Ubuntu]]

==== Ubuntu вариант запуска процесса вручную ====

=== Установка ===
<code>
root@nodeN:~# apt-get install ucarp
</code>

=== Настройка ===
<code>
root@nodeN:~# cat /etc/vip-up.sh
</code><code>
#!/bin/sh
/sbin/ip addr add 192.168.X.254/32 dev "$1"
</code><code>
root@nodeN:~# cat /etc/vip-down.sh
</code><code>
#!/bin/sh
/sbin/ip addr del 192.168.X.254/32 dev "$1"
</code><code>
root@nodeN:~# chmod +x /etc/vip-up.sh /etc/vip-down.sh
</code>

=== Запуск (можно прописать в /etc/rc.local) ===
<code>
root@node1:~# ucarp -i eth0 -s 192.168.X.1 -v 1 -p secret -a 192.168.X.254 -u /etc/vip-up.sh -d /etc/vip-down.sh -z -B

root@node2:~# ucarp -i eth0 -s 192.168.X.2 -v 1 -p secret -a 192.168.X.254 -u /etc/vip-up.sh -d /etc/vip-down.sh -z -B
</code>
Примечания:

  * Не смотря на ОБЯЗАТЕЛЬНОЕ наличие ключа -a 192.168.X.254 адрес повторно приходится присваивать/удалять в скриптах
  * If you want a "preferred" master to immediately become a master even if another host is already the master: a) add the --preempt (or -P) switch to *all* hosts b)use a lower skew (-k) or a lower base for the "preferred" one.

=== Проверка ===
<code>
root@nodeN:~# ip addr show dev eth0
</code>

=== Остановка ===
<code>
root@nodeN:~# killall ucarp
</code>

==== FreeBSD (kernel land) ====

  * [[http://www.freebsd.org/doc/en/books/handbook/carp.html|Common Address Redundancy Protocol (CARP) (freebsd handbook)]]

# man carp

[[Управление ядром и модулями в FreeBSD]]

=== Настройка ===

<code>
node1# ifconfig carp0 create
node1# ifconfig carp0 vhid 1 pass testpass321 192.168.X.254/24

node2# ifconfig carp0 create
node2# ifconfig carp0 vhid 1 advskew 100 pass testpass321 192.168.X.254/24

node1# cat /etc/rc.conf
</code><code>
...
cloned_interfaces="carp0"
ifconfig_carp0="vhid 1 pass testpass321 192.168.X.254/24"
...
</code><code>
node2# cat /etc/rc.conf
</code><code>
...
cloned_interfaces="carp0"
ifconfig_carp0="vhid 1 advskew 100 pass testpass321 192.168.X.254/24"
...
</code>

=== Проверка ===
<code>
nodeN# ifconfig carp0
</code>