Linux Open Telnet Service (summary)

Linux Open Telnet Service
1. Basic knowledge
The Linux delivery service is performed by a daemon running in the background (daemon).
The daemon's job is to open 1 ports (port) and wait for (listen) incoming connections. In C/S mode, if the customer draws 1 connections, the daemon creates (fork) the child process to respond to the connection, and the parent process continues to listen for requests for other services.
However, for every 1 services provided by the system, it is often a waste of system resources if you must run 1 daemons that monitor the occurrence of a port connection. To do this, introduce the Extended Network Daemon service xinetd (xinetd Internet daemon). The Telnet service is also guarded by xinetd.

2. Detect if Telnet, telnet-server RPM packages are installed
Os:redhat9

[root@localhost Root] #rpm-qa telnet
telnet-0.17-25
TELNET*.RPM is installed by default//
[root@localhost Root] #rpm-qa telnet-server
Empty
TELNET*.RPM is not installed by default//

3. Install Telnet-server
There's a telnet-server-0.17-25.i386.rpm on the 3rd plate.
[root@localhost Root] #rpm-IVH telnet-server*.i386.rpm

4. Modifying the Telnet service configuration file
Vi/etc/xinetd.d/telnet
Service Telnet
{
Disable = yes
Flags = Reuse
Socket_type = Stream
wait = no
user = root
Server =/usr/sbin/in.telnetd
Log_on_failure + + USERID
}

Add the Disable=yes line before the #, or change to Disable=no
Ps:
After installing Telnet-server, the system has files/usr/sbin/in.telnetd

5. Restarting the xinetd daemon
Because the Telnet service is also guarded by xinetd, the telnet-server must be restarted to start the Telnet service when the installation is complete xinetd
[root@localhost Root] #service xinetd restart
Or
[Root@localhost root]#/etc/init.d/xinetd Restart

6. Shut down the system's firewall
Linux system default firewall is "high"

Command-line Interface CLI:
[Root@localhost root]# Setup
Choice: "Firewall Configuration"
Option: Security level--"no firewall"

7. Test
Telnet IP

QUOTE:
Red Hat Linux Release 9 (shrike)
Kernel 2.4.20-8 on a i686
Login
appear, it's OK.

8. Telnet default boot up
1). Command NTSYSV
Find Telnet, activate (*) service with the space key
2). Command Chkconfig
Chkconfig--add Telnet
Chkconfig Telnet on
3). GUI for graphical user interface
Redhat-conhat-config-services
Or
"Main Menu"--"system settings"--"Server Settings"--"services"

Ps:
It is not safe to use the SSH (Secure shell) alternative because Telnet is a plaintext transfer password.
Windows General f-secure ssh, putty ssh