Article · Wikipedia archive · Last revised Jul 12, 2026

Pfsync

pfsync is a computer protocol used to synchronise firewall states between machines running Packet Filter (PF) for high availability. It is used along with CARP to make sure a backup firewall has the same information as the main firewall. When the main machine in the firewall cluster dies, the backup machine is able to accept current connections without loss.

Last revised
Jul 12, 2026
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Pfsync
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pfsync is a computer protocol12 used to synchronise firewall states between machines running Packet Filter (PF) for high availability. It is used along with CARP to make sure a backup firewall has the same information as the main firewall. When the main machine in the firewall cluster dies, the backup machine is able to accept current connections without loss.345

See also

See also

References

References

  1. "/etc/protocols". BSD Cross Reference. OpenBSD. pfsync 240
  2. "/sys/net/if_pfsync.h". BSD Cross Reference. OpenBSD.
  3. Federico Biancuzzi (2004-04-15). "OpenBSD PF Developer Interview". ONLamp. O'Reilly Media. Archived from the original on 2004-05-08. Retrieved 2019-03-20.
  4. Federico Biancuzzi (2004-05-06). "OpenBSD PF Developer Interview, Part 2". ONLamp. O'Reilly Media. Archived from the original on 2004-06-19. Retrieved 2019-03-20.
  5. "State Synchronization (pfsync) Overview | pfSense Documentation". docs.netgate.com. Retrieved 2026-02-16.
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