Detailed explanation of Linux SSH version checking method

[Title] Detailed explanation of Linux SSH version checking method

SSH (Secure Shell) is a network protocol used for remote login and command execution, commonly used in Linux systems superior. With the continuous development of technology, the SSH protocol is constantly updated and upgraded, and checking the SSH version is an important part of ensuring system security. This article will introduce in detail how to check the SSH version under Linux, and attach specific code examples.

1. Check the installed SSH version number

1. Use the command to check the SSH server version number:

   ssh -V

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   Run the above command, you can In the terminal output, you can see the version number information of the SSH server, such as "OpenSSH_7.9p1".

2. Use the command to check the SSH client version number:

   ssh -V

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   Similarly, run the above command in the terminal to check the SSH client version number.

2. Check the SSH configuration file

1. Open the SSH configuration file:

   sudo nano /etc/ssh/sshd_config

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   In the configuration file, you can find the information about SSH version information. Common configuration items are as follows:

   # SSH协议版本设置
   # Protocol 2, 1

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   By default, Protocol is set to "2", indicating that only SSH protocol version 2 is supported. If you need to set up support for SSH versions 1 and 2, you can uncomment "Protocol 2, 1" and restart the SSH service to take effect.

3. Use nmap to detect SSH version

1. Install the nmap tool:

   sudo apt install nmap

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2. Use nmap Detect SSH port information, including SSH version:

   nmap -sV -p 22 服务器IP地址

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   Run the above command, nmap will scan the server's SSH port and list the relevant version information, including the SSH version number.

4. SSH Vulnerability Scanning Tool

In addition to manually checking the SSH version, you can also use some special tools to scan and detect possible vulnerabilities.

1. Use the SSH weak password scanning tool ssh_scan:

   git clone https://github.com/mozilla/ssh_scan.git
   cd ssh_scan
   bundle install
   bundle exec ruby bin/ssh_scan --timeout 30 --user admin 服务器IP地址

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   The above code example uses the ssh_scan tool to scan the SSH port of the server to detect possible weak password risks.

2. Use the SSH vulnerability scanning tool ssh-audit:

   git clone https://github.com/arthepsy/ssh-audit.git
   cd ssh-audit
   python3 ssh-audit.py 服务器IP地址

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   The ssh-audit tool can be used to comprehensively detect the SSH configuration, including version vulnerabilities, encryption algorithm strength, etc. .

Conclusion

Through the above methods and tools, you can easily check the SSH version, discover potential security risks in a timely manner and take corresponding measures to strengthen system security. When using the SSH protocol, maintaining timely updates and management is an indispensable part of ensuring system security. I hope this article will be helpful to readers, and I hope everyone will pay more attention to security issues in system management.

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