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Introduction to 1.SSH

SSH is an acronym for Secure Shell and was developed by bai IETF's network team (Network Working Group). SSH is a security association that builds du on the application layer. SSH is currently a reliable protocol designed to provide security for remote login sessions and other network services. The use of SSH protocol can effectively prevent information leakage in the process of remote management. SSH was originally a program on the UNIX system, and then rapidly expanded to other operating platforms. When used correctly, SSH can make up for loopholes in the network. The SSH client is suitable for a variety of platforms. Almost all UNIX platforms-including HP-UX, Linux, AIX, Solaris, Digital UNIX, Irix, and others-can run SSH.

two。 Function

Traditional network service programs, such as ftp, pop and telnet, are inherently insecure because they transmit passwords and data in clear text on the network, which can be easily intercepted by people with ulterior motives. Moreover, the security verification method of these service programs also has its weakness, that is, it is vulnerable to the attack of "man-in-the-middle". The so-called "man in the middle" attack is that the "man in the middle" pretends to be a real server to receive the data you send to the server, and then passes the data to the real server by pretending to be you. After the data transfer between the server and you is tampered with by the "middleman", there will be serious problems. By using SSH, you can encrypt all transmitted data so that man-in-the-middle attacks are not possible, and can prevent DNS spoofing and IP spoofing. An added benefit of using SSH is that the data transferred is compressed, so the transfer can be accelerated. SSH has many functions. It can not only replace Telnet, but also provide a secure "channel" for FTP, PoP, and even PPP.

Command to restart the ssh service:

Service sshd restartsystemctl restart sshd.service

Use of the ssh command

1. Check to see if ssh is installed

Type "rpm-qa | grep ssh" on the command line. In general, the linux system has been installed by default when installing the system. If the ssh is uninstalled in the system, you can use the command "yum-y install ssh" to install it.

Start and stop of 2.ssh service

As with the operations of other services, the ssh service starts and stops using the commands "systemctl start sshd" and "systemctl stop sshd".

3. Connect to a remote server

Type "ssh-l root server IP" on the command line to connect to the server or use "ssh root@ server IP" to connect to the server.

Modification of 4.ssh configuration

Enter the "vi / etc/ssh/sshd_config" command on the command line to go to the configuration page of ssh, where you can modify the parameters.

These are the details of what the command to restart the ssh service is. For more information, please follow other related articles!

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