Application and implementation of SSH port forwarding in Linux SysOps

Application and implementation of SSH port forwarding in Linux SysOps

Abstract:
SSH (Secure Shell) is a secure remote login protocol designed to Protect the security of data transmission. In addition to regular remote login, SSH also has an important function - port forwarding. This article will introduce the application and implementation of SSH port forwarding in Linux SysOps and provide specific code examples.

1. What is SSH port forwarding
   SSH port forwarding is a network technology that forwards local ports to remote hosts. It allows users to map a certain port on the local host to a specified port on the remote host through an SSH channel to access local services on the remote host, or access remote services on the local host. Port forwarding can be divided into local port forwarding and remote port forwarding.
2. Application and implementation of local port forwarding
   Local port forwarding is usually used to map services on the local host to remote hosts for access. For example, let's say your localhost is running a web server, but for some reason you can't expose it directly to the internet. Through the local port forwarding function of SSH, the web server on the local host can be mapped to a specified port on the remote host (usually port 22), so that the web server on the local host can be accessed through the remote host.

The specific implementation steps are as follows:
1) Run the following command on the local host to establish an SSH connection, and map the 8888 port of the local host to the 80 port of the localhost of the remote host:

ssh -L 8888:localhost:80 user@remote_host

2) Run the following command on the remote host to start the web server:

sudo systemctl start apache2

3) Now, you can access the web on the local host by entering localhost:8888 in the browser on the remote host The server is gone.

3. Application and implementation of remote port forwarding
   Remote port forwarding is usually used to access services on the remote host on the local host. For example, suppose there is a database service running on a remote host, but for some reason it is not directly accessible. Through the remote port forwarding function of SSH, the database service on the remote host can be mapped to the specified port on the local host, so that the database service on the remote host can be accessed on the local host.

The specific implementation steps are as follows:
1) Run the following command on the local host to establish an SSH connection, and map the 3306 port of the remote host to the 8888 port of the localhost of the local host:

ssh -R 8888:localhost:3306 user@remote_host

2) Now, the database service on the remote host can be accessed through localhost:8888 on the local host.

4. Security Considerations
   When using SSH port forwarding, there are some security considerations to pay attention to:
5. To ensure the security of SSH connections, use key authentication instead of password authentication.
6. Avoid exposing the SSH service port to the public network, and only allow specific IP addresses to access the SSH service as much as possible.
7. For open port forwarding, careful authorization is required and only necessary users are allowed to access.

Conclusion:
SSH port forwarding is a very useful feature in Linux SysOps. It provides users with a safe and convenient way to access services on remote hosts. Through the introduction and specific code examples of this article, readers can further understand the application and implementation of SSH port forwarding, and use it flexibly in actual work. At the same time, in order to ensure security, we should also set up the SSH service carefully and follow relevant security best practices.

The above is the detailed content of Application and implementation of SSH port forwarding in Linux SysOps. For more information, please follow other related articles on the PHP Chinese website!