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  1. 1. TELNET A network protocol that allows a user on one computer to log into another computer that is part of the same network. What is Telnet? Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers. Through Telnet, an administrator or another user can access someone else's computer remotely. On the Web, HTTP and FTP protocols allow you to request specific files from remote computers, but not to actually be logged on as a user of that computer. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer. A Telnet command request looks like this (the computer name is made-up): telnet The result of this request would be an invitation to log on with a userid and a prompt for a password. If accepted, you would be logged on like any user who used this computer every day. Telnet is most likely to be used by program developers and anyone who has a need to use specific applications or data located at a particular host computer. How Telnet Works Telnet uses software, installed on your computer, to create a connection with the remote host. The Telnet client (software), at your command, will send a request to the Telnet server (remote host). The server will reply asking for a user name and password. If accepted, the Telnet client will establish a connection to the host, thus making your computer a virtual terminal and allowing you complete access to the host's computer.
  2. 2. Telnet requires the use of a user name and password, which means you need to have previously set up an account on the remote computer. In some cases, however, computers with Telnet will allow guests to log on with restricted access. How to configure telnet server in Linux You invoke the Telnet utility with the keyword telnet. If you know the name of the site you want to connect with, you can enter telnet and the name of the site on the Linux command line. CAUTION The original version of Telnet is noted for being very insecure. For secure connections over a network or the Internet, you should use the Secure Shell (SSH). SSH operate in the same way as the original but use authentication and encryption to secure the Telnet connection. Even so, it is advisable never to use Telnet to log in to your root account. That why by defaults root account is disable for root login. Configure telnet server In this example we will configure a telnet server and will invoke connection from client side. For this example we are using three systems one linux server one linux clients and one window clients. A linux server with ip address and hostname Server A linux client with ip address and hostname Client1 A windows xp system with ip address and hostname Client2 Updated /etc/hosts file on both linux system Running portmap and xinetd services Firewall should be off on server We suggest you to review that article before start configuration of telnet server. Once you have completed the necessary steps follow this guide. Four rpm are required to configure telnet server. telnet, telnet-server, portmap, xinetd check them if not found then install Now check telnet, portmap, xinetd service in system service it should be on #setup Select System service from list [*]portmap [*]xinetd [*]telnet
  3. 3. Now restart xinetd and portmap service To keep on these services after reboot on then via chkconfig command After reboot verify their status. It must be in running condition Create a normal user named vinita On Linux client ping from telnet server and run telnet command and give user name and password On Window client ping from telnet server and run telnet command Give user name and password
  4. 4. How to enable root login from telnet server On linux server open file securetty In the end of file add pts/0 to enable one telnet session for root. if you need to open more telnet session for root and add more pts/1 pts/2 and so on. Now restart xinetd and portmap service Verfiy from window by login from root