Server Administration

Sunday, July 24

How to disable TELNET Service in Linux

Note: This exercise is performed on two Linux VMs (Linux1 and Linux2).

Verify TELNET rpm installed?

[root@linux1 ~]# rpm -qa telnet

telnet-0.17-39.el5

[root@linux1 ~]#

Verify that TELNET service is running

[root@linux1 ~]# telnet linux2

Trying 192.168.2.102...

Connected to linux2 (192.168.2.102).

Escape character is '^]'.

linux2 (Linux release 2.6.18-238.el5 #1 SMP Sun Dec 19 14:24:47 EST 2010) (2)

Password:

Edit and disable to yes on all the servers

[root@linux1 ~]# vi /etc/xinetd.d/krb5-telnet

[root@linux1 ~]# cat /etc/xinetd.d/krb5-telnet

# default: off

# description: The kerberized telnet server accepts normal telnet sessions, \

# but can also use Kerberos 5 authentication.

service telnet

{

flags = REUSE

socket_type = stream

wait = no

user = root

server = /usr/kerberos/sbin/telnetd

log_on_failure += USERID

disable = yes

}

[root@linux1 ~]#

Restart the service

[root@linux1 ~]# /etc/rc.d/init.d/xinetd restart

Stopping xinetd: [ OK ]

Starting xinetd: [ OK ]

[root@linux1 ~]#

[root@linux1 ~]# service xinetd status

Try now

[root@linux1 ~]# telnet linux2

Trying 192.168.2.102...

telnet: connect to address 192.168.2.102: Connection refused

telnet: Unable to connect to remote host: Connection refused

[root@linux1 ~]#