sshd:192.168.0.1:allow #Allow SSH login from the IP address 192.168.0.1
sshd:192.168.0.:allow #Allow users with the IP address of 192.168.0.1/24 to log in. Multiple network segments can be separated by commas, such as 192.168.0.,192.168.1.:allow
sshd:ALL #Reject all IP
When the two files hosts.allow and hosts.deny set rules at the same time, the priority of the rules in the hosts.allow file is higher. After this method is set, the server only allows SSH login from the IP address 192.168.0.1, and all other IPs will be rejected .