Telnet server
Install
rpm -qa | grep telnet
telnet-0.17-39.el5
telnet-server-0.17-39.el5
Setup
vim /etc/xinetd.d/telnet
service telnet
{
        flags           = REUSE
        bind            = 192.168.1.51
        only_from       = 192.168.1.0/24
        no_acess        = 192.168.1.11
        access_times    = 9:0-18:0  
        instance        = 10
        umask           = 022
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = no
}
[root@centos1 ~]# /etc/init.d/xinetd restart
Stopping xinetd:                            [  OK  ]
Starting xinetd:                            [  OK  ]
[root@centos1 ~]# netstat -tlup
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name  
tcp        0      0 centos1:2208                *:*                         LISTEN      3554/hpiod         
tcp        0      0 *:sunrpc                    *:*                         LISTEN      3246/portmap       
tcp        0      0 *:telnet                    *:*                         LISTEN      14549/xinetd       
Security
iptables -A INPUT -p tcp i $INIF -s 192.168.1.0/24   --dport 23 -j ACCEPT
iptables -A INPUT -p tcp i $EXTIF -s 119.145.111.137 --dport 23 -j ACCEPT
iptables -A INPUT -p tcp i $EXTIF -s 1               --dport 23 -j DROP
vim /etc/hosts.allow
in.telnetd:192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.4,192.168.1.5
vim /etc/hosts.deny
intelnetd:ALL