Hello, I have Debian 'Stretch' pre-installed with isc-dhcp-server 4.3.5-3 to have failover mode (two computers/servers [primary/secondary]).
https://kb.isc.org/docs/aa-00502 NOTE: I found that FQDN in fields 'address' and 'peer address' does not work, IP address works fine (command 'host' resolves short and FQDN names fine what indicates that resolver works properly) DHCP servers are up and running, failover mode was configure with OMAPI secret key, failover mode works fine. https://kb.isc.org/docs/aa-01355 There is one issue: -- on secondary DHCP server in log files I see messages Can't start OMAPI protocol: address not available (5 sec interval) failover peer failover-partner: invalid argument (30 sec interval) Primary DHCP server has firewall running and ports 7911, 519 are allowed in. Secondary DHCP server has not firewall rules and all communication is permitted. For a test I use 'netcat' to verify that network ports are open. root# nc primary 7199 [Ok] root# nc primary 519 [Ok] On primary DHCP server connection looks OK. On secondary DHCP server when I connect to port 520 in reply I get only character 'd' -- what is different from what I see in reply from primary DHCP server (I am not familiar with OMAPI protocol, probably reply 'd' could be a normal response). root# nc secondary 7199 [Ok] root# nc secondary 520 [???] An attempt to use OMAPI shell to shutdown secondary DHCP server had no effect https://kb.isc.org/docs/aa-00475 I looked for a method to trouble shoot this situation and so far nothing points to the source of the log messages. Is there a methodic to troubleshoot OMAPI log messages? Thank you John
