http://ubuntu-tutorials.com/2007/09/02/network-security-with-tcpwrappers-hostsallow-and-hostsdeny/

gate# ldd /usr/sbin/sshd | grep wrap

gate# cat /etc/hosts.allow

ALL: 127.0.
sshd: 192.168.X.10

gate# cat /etc/hosts.deny

ALL:ALL

# cat /etc/hosts.allow

...
#ALL : ALL : allow
sshd: 192.168.8.10: allow
sshd: all: deny
...