# apt install tcpd # cat /etc/hosts.allow sshd: 127.0.0.1 [::1] sshd: 192.168. sshd: .jp # cat /etc/hosts.deny sshd: ALL # tcpdchk -v Using network configuration file: (null) >>> Rule /etc/hosts.allow line 10: daemons: sshd clients: 127.0.…