How to Disable Telnet - Web Hosting Forums Web Discussions on Hosting Webmaster forums Web Hosting Forums Domain Name Forums Web Hosting

incript_services · 08-29-2005, 09:09 PM

Telnet sends clear text passwords and usernames through logins and should be disabled on all web servers and replaced with SSH.
Some hosting providers are not disabling telnet by default but you should ensure that it has been turned off as it's a great security risk to your servers. TELNET server listens for incoming messages on port 23, and sends outgoing messages to port 23.

1. Login to your server through SSH and su to root.

2. Type pico /etc/xinetd.d/telnet

3. Look for the line: disable = no and replace with disable = yes

4. Now restart the inetd service: /etc/rc.d/init.d/xinetd restart

5. Turn off it through chkconfig as well because it can still start through that.
/sbin/chkconfig telnet off

6. Scan your server to ensure port 23 is closed.
nmap -sT -O localhost
Also run ps -aux | grep telnet and if you find anything other than "grep telnet" as result kill the process.

aexx · 08-29-2005, 09:14 PM

thanks id be sure to use your method

incript_services · 08-29-2005, 09:15 PM

Oh sure And thanks for the reply.Tell Me if you have problems regarding this.

SERVEREMPIRES · 10-05-2005, 07:33 PM

well incript_services have lots of knowledge in this.keep it up dude

wilo · 10-07-2005, 12:20 AM

this is good essential basic stuff. I remember hearing a lot of bad stuff about telnet hacker attacks and their vulnerabilities. Thanks for guiding me a bit.

IndiaHost · 01-14-2008, 08:58 PM

Hello,

A very good tutorial for a newbie.
If the users uses telnet any body can sniff, data and root password over the network as it sent in plain text format. Thus you can use SSH as it sends data in encrypted form with same features and secure environment.

Thank you.