By default, FastNetMon cleans up all blackhole or flow spec announces during restart/commit operation. But you can disable this behavior and do not unblock blocked hosts during restart.

NB! This logic is known to cause issues with BGP announces when you do restarts of FastNetMon and BGP daemon in same time (what happens during server reboot). It will cause missing announces as it does not re-announces previously blocked hosts to BGP daemon.

This logic is useful only if you do not use BGP at all. I.e. if you rely only on callback scripts. In this case it will work fine.

To enable this logic you need to run following commands:

sudo fcli set main keep_blocked_hosts_during_restart true
sudo fcli set main do_not_withdraw_unicast_announces_on_restart true
sudo fcli commit

FastNetMon can do same for BGP Flow Spec announces and you can enable such logic this way:

sudo fcli set main do_not_withdraw_flow_spec_announces_on_restart true
sudo fcli set main keep_flow_spec_announces_during_restart true
sudo fcli commit

After these changes, FastNetMon will store / load blackhole list or flow spec ban list during commit / restart operation. Flags do_not_withdraw_unicast_announces_on_restart and do_not_withdraw_flow_spec_announces_on_restart disable automatic BGP clean up after restart and BGP daemon will keep announces until FastNetMon removes it.

Starting from version 2.0.357 FastNetMon can store/load blocked hostgroups to/from persistent storage too:

sudo fcli set main keep_blocked_hostgroups_during_restart true
sudo fcli commit

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