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This article introduces the relevant knowledge of "the basic use of telnet services under the Linux system". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

one。 Enable the telnet service

For security reasons, linux does not allow telnet by default. If you need to use the telnet service, first you need to turn on the service.

The methods are as follows:

1.

The code is as follows:

Cp / etc/xinetd.d/telnet / etc/xinetd.d/telnet.bak

(first of all, make a backup in case there is a problem in the future. Get into this habit.)

two。

The code is as follows:

Vi / etc/xinetd.d/telnet

Change the ending disable=yes to no. Save exit

3. Restart the xinetd service

The code is as follows:

Service xinetd restart

OK, now you can use the telnet service (of course your firewall settings are allowed)

4. Allow telnet service to be started automatically when powered on

Because telnet is integrated into xinetd, you can just start xinetd when you turn it on.

The code is as follows:

Ntsysv

Choice

The code is as follows:

Xinetd

Or

The code is as follows:

Chkconfig xinetd-level 345 on

Ok as soon as you enter.

Second, allow root to log in.

Method 1:

Edit / etc/pam.d/login, remove

The code is as follows:

Auth required / lib/security/pam_securetty.so

This sentence

Method 2:

Edit / etc/securetty

Add at the end:

The code is as follows:

Pts/0,pts/1...

(adding a pts/0 will allow a root login, and adding to pts/n will allow a root login. )

Matters needing attention in using telnet

1. For security purposes, it is good not to allow login as root.

2. If you need root permission to perform tasks, you can do this:

The code is as follows:

Telnet 192.168.0.7 (your host IP)

Type your login name, such as bill, after login:

Enter your password after password:

You can log in successfully.

Then at the prompt, enter: su-root

Enter the password for root. You can perform the duties of root. Note: if you enter su directly, and then enter the root password, you may be prompted: "comman is not find"

4. Set the telnet port

The code is as follows:

# vi / etc/services

Find telnet after entering edit mode (enter / telnet in vi editing mode)

You will find the following:

The code is as follows:

Telnet 23/tcp

Telnet 23/udp

Change 23 to an unused port number (such as 2000), exit vi, restart the telnet service, and the default port number of Telnet is changed.

V. restrictions on Telnet services

Telnet sends passwords and data in clear text, and if you are not satisfied with its default settings, it is necessary to limit its scope of service. Assuming that the ip of your host is 210.45.160.17, you can set it as follows, ^ _ ^!

The code is as follows:

# vi / etc/xinetd.d/telnet

Service telnet

{

Disable = no # activate the telnet service, no

Bind = 210.45.160.17 # your ip

Only_from = 210.45.0.0amp 16 # only allows access to the network segment 210.45.0.0 ~ 210.45.255.255

Only_from = .edu.cn # only Education Network can enter!

No_access = 210.45.160. {115116} # these two ip are not logged in

Access_times = 8:00-12:00 20:00-23:59 # Service is open only during these two hours of the day

.

}

This is the end of the content of "basic usage of telnet Services under the Linux system". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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