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124 lines
4.3 KiB
ReStructuredText
124 lines
4.3 KiB
ReStructuredText
=====================================
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High Availability
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=====================================
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OPNsense utilizes the Common Address Redundancy Protocol or CARP for hardware
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failover. Two or more firewalls can be configured as a failover group. If one
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interface fails on the primary or the primary goes offline entirely, the
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secondary becomes active.
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Utilizing this powerful feature of OPNsense creates a fully redundant firewall
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with automatic and seamless fail-over. While switching to the backup network
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connections will stay active with minimal interruption for the users.
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.. image:: images/light_bulbs.png
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:width: 100%
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-----------------------------
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Workflow
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-----------------------------
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Although its not required to synchronize the configuration from the master machine to the backup, a lot of people
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would like to keep both systems (partially) the same.
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To prevent issues spreading over both machines at the same time, we choose to only update on command (see the status page).
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Our workflow looks like this:
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.. blockdiag::
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:desctable:
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blockdiag {
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update1 [label="Master\nUpdate 1"];
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update2 [label="Master\nUpdate 2"];
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updaten [label="Master\nUpdate N"];
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sync [label="Synchronize\nBackup"];
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update1 -> update2 ;
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update2 -> updaten [label=".."];
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updaten -> sync;
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}
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First commit all changes to the master, then update the backup while knowing the master is still properly configured.
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.. Note::
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In case of an emergency, you should still be able to switch to the backup node when changes cause issues, since
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the backup machine is left in a known good state during the whole process.
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-----------------------------
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Automatic replication
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-----------------------------
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Although we advise to make sure to keep the backup machine intact during maintenance, some people prefer to keep
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the backup in sync on periodic intervals. For this reason we added a cron action which you can schedule yourself
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in :menuselection:`System -> Settings -> Cron` on the primary node.
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To use this feature, add a new cron job containing the :code:`HA update and reconfigure backup` command and a
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proper schedule, once a day outside office hours is usually a safe option.
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.. Note::
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To prevent a non functional primary machine updating the active master, the :code:`HA update and reconfigure backup`
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will only execute if all carp interfaces are in :code:`MASTER` mode.
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-----------------------------
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Settings
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-----------------------------
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............................
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Automatic failover
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............................
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Although not really a setting on the high availability setup page, it's a crucial part of high available setups.
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Using CARP type virtual addresses, the secondary firewall will take over without user intervention and minimal
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interruption when the primary becomes unavailable.
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Virtual IPs of the type CARP (:doc:`/manual/firewall_vip`) are required for this feature.
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............................
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Synchronized state tables
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............................
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The firewall’s state table is replicated to all failover configured firewalls.
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This means the existing connections will be maintained in case of a failure,
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which is important to prevent network disruptions.
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............................
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Disable preempt
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............................
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By default this option is deselected, which is the advised scenario for most common HA setups.
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The preempt option make sure that multiple carp interfaces will act as a group (all :code:`backup` or :code:`master`)
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at the same time, assuming no technical issues exist between both.
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.................................
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Configuration synchronization
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.................................
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OPNsense includes configuration synchronization capabilities. Configuration
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changes made on the primary system are synchronized on demand to the secondary firewall.
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............................
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Configure HA CARP
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............................
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For detailed setup guide see: :doc:`/manual/how-tos/carp`
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-----------------------------
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Status
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-----------------------------
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The status page connects to the backup host configured earlier and show all services running on the backup server.
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With this page you can update the backup machine and restart services if needed.
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.. Tip::
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.. raw:: html
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Use the refresh <i class="fa fa-refresh fa-fw"></i> button to update the backup node and restart all services at once.
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