Unix/inetd

/etc/xinetd.d & /etc/xinetd.conf

service telnet
{
        socket_type     = stream
        protocol        = tcp
        wait            = no
        user            = telnetd
        group           = telnetd
        server          = /usr/sbin/in.telnetd
    only_from       = localhost 163.1.183.163 163.1.183.14 163.1.124.142
    only_from       = 10.0.0.0/8
}

/etc/inetd.conf
telnet stream tcp nowait root /usr/sbin/tcpd in.telnetd

With both version of inetd you can disable things by commenting the line or section (prefex each line with a # character).

/usr/sbin/tcpd is a wrapper program that allows us to control access to the service using /etc/hosts.deny and /etc/hosts/allow.

• Access will be granted when a (daemon,client) pair matches an entry in the /etc/hosts.allow file.

• Otherwise, access will be denied when a (daemon,client) pair matches an entry in the /etc/hosts.deny file.

• Otherwise, access will be granted.

E.g. I have in my /etc/hosts.deny
leafnode: ALL EXCEPT LOCAL