Hi The path to the system-wide known_hosts file is /etc/ssh/ssh_known_hosts and not /etc/ssh/known_hosts. See auth2-hostbased.c line 221-223.
Best, Martin Index: sshd_config.5 =================================================================== RCS file: /cvs/src/usr.bin/ssh/sshd_config.5,v retrieving revision 1.340 diff -u -p -r1.340 sshd_config.5 --- sshd_config.5 31 Mar 2022 17:58:44 -0000 1.340 +++ sshd_config.5 10 Apr 2022 20:35:39 -0000 @@ -818,7 +818,7 @@ should ignore the user's during .Cm HostbasedAuthentication and use only the system-wide known hosts file -.Pa /etc/ssh/known_hosts . +.Pa /etc/ssh/ssh_known_hosts . The default is .Dq no . .It Cm Include
