In-depth introduction to SSH protocol Forwarding (1)

The use of networks is inseparable from the deployment of security measures. There are also related security protocols in the network itself. Today we will introduce the SSH protocol. So how can we reflect the role of the SSH protocol in specific settings? Let's introduce the relevant content today. In this article, you can learn how to apply the SSH port forwarding mechanism to solve some problems in daily work/life. You can also use port forwarding to encrypt network applications in a non-secure environment, protect personal privacy and important business information. At the same time, this technology can be used to solve some common problems in the work, such as the restrictions imposed by firewalls and network applications ｡

Overview

When you enjoy free WiFi in a cafe, do you think someone may be stealing your password and privacy information? When you find that the lab firewall has blocked your network application port, is it difficult? Let's see what benefits the SSH port forwarding function can bring to us!

Port forwarding Overview

Let's take a look at the concept of port forwarding. We know that the SSH protocol automatically encrypts and decrypts network data between all SSH clients and the server. However, SSH also provides a very useful function, namely port forwarding. It can forward network data of other TCP ports through SSH links, and automatically provides the corresponding encryption and decryption services. This process is also called tunneling ), this is because SSH provides a secure channel for transmission for other TCP links. For example, TCP applications such as Telnet, SMTP, and LDAP can benefit from this and avoid user names, transmission of passwords and private information in plain text. At the same time, if the firewall in your work environment limits the use of some network ports, but allows SSH connections, the TCP port forwarding can also be used for SSH communication. In general, SSH port forwarding can provide two main functions:

Encrypts the communication data between the SSH Client and the SSH Server ｡

Figure 1. SSH port forwarding

As shown in, after port forwarding is used, TCP port A and port B do not communicate directly, but are forwarded to the SSH client and server for communication, in this way, data encryption is automatically implemented and firewall restrictions are bypassed at the same time ｡