The method of setting Telnet under Linux system

The method of setting Telnet under Linux system

Configuration steps for Telnet service under Linux system:

First, install Telnet software package (usually two)

1, telnet-client (or Telnet), this package provides the Telnet client program;

2, Telnet-server, this package provides a Telnet server-side program;

Check to see if these packages are installed before installing the following methods:

[Root@echo Root] #rpm –q Telnet or [root@wljs root] #rpm –q telnet-client

[Root@echo Root] #rpm –q telnet-server

If a package is not detected and needs to be installed, Red Hat Linux 9 defaults to a Telnet package installed, typically just install the Telnet-server package.

1. Get the telnet-server-0.17-25.i386.rpm package in the Red Hat Linux 9 installation disk 3.

2. Installation package

[Root@echo Root] #rpm – I telnet-server-0.17-25.i386.rpm

Second, start Telnet service

1, open the service

Method One: Use Ntsysv, in the window that appears, will telnet front * Plus, then press OK.

Method Two: Edit/etc/xinetd.d/telnet

[Root@echo root]# Vi/etc/xinetd.d/telnet

Find Disable = Yes to change Yes to No.

2. Activate service

[Root@echo root]# Service xinetd restart

Third, testing services

[Root@echo Root] #Telnet IP (or hostname)

If configured correctly, you are prompted to enter the username and password for the remote machine

Login:

PassWord:

Note: Only normal users are allowed by default

Four, set Telnet port

#vi/etc/services

Look for Telnet after entering edit mode (vi edit mode input/telnet)

Will find the following:

Telnet 23/tcp

Elnet 23/UDP

Change 23 to unused port number (e.g. 2000), exit VI, restart Telnet service, and the Telnet default port number is modified.

V. Telnet service Restrictions

Telnet transmits passwords and data in plaintext, and if you are dissatisfied with its default settings, it is necessary to limit the scope of its services. Assuming that your host's IP is 210.45.160.17, you can set it as follows.

#vi/etc/xinetd.d/telnet

Service Telnet

{

Disable = no #激活 Telnet service, no

IND = 210.45.160.17 #your IP

Only_from = 210.45.0.0/16 #只允许 210.45.0.0 ~ 210.45.255.255 This network segment enters

Only_from =. edu.cn #只有教育网才能进入!

No_access = 210.45.160. #这两个ip不可登陆

access_times= 8:00-12:00 20:00-23:59 # Only two hours a day open the service

......

}

Telnet Root User Login

Telnet is not very secure, and the default is not to allow root to telnet into the linux/"Target=_blank>linux host." To allow root users to log in, you can use the following methods:

[Root @echo/root]# Vi/etc/pam.d/login

#auth Required pam_securetty.so #将这一行加上注释!

Or

[Root@echo root]# Mv/etc/securetty/etc/securetty.bak

This way, root can go directly to the Linux host. However, it is not recommended to do so. You can also switch to root after the average user enters and have root privileges.

Note: The Telnet server is not installed in my FC4 because there is already krb5-telnet. Go directly to step two.

Vi/etc/xinetd.d/krb5-telnet is OK.