Transmitting data openly over the internet carries the risk of unauthorized interception of information, passwords and so on. To avoid such risks and ensure secure connections, file copying and downloading, as well as remote control of another computer, a special tunnel technology called SSH was created.
SSH is most widely used to provide interaction between users' computers and hosting servers. This connection algorithm, which ensures secure file transfer, has successfully taken over the functions of previously existing protocols such as rsh, rlogin, rcp and others. Here are just some of the capabilities provided by an ssh tunnel built on this technology:
- Remote work with a server;
- Use of encryption algorithms when exchanging information;
- Secure connection using any network protocols;
- Encrypted transfer of text, video and audio files;
- Preliminary data compression;
- Elimination of any possibility of interception of or interference with the communication session.
The legendary ssh client – putty
SSH technology requires certain software. To establish a secure connection you will need the appropriate software on the Linux server, as well as user-side software, the so-called «client».
Webmasters usually choose a client application for connecting based on the tasks at hand. However, the ssh client putty, with its intuitive graphical interface, is rightfully considered the most popular among Windows OS users in terms of convenience and functionality.
The PuTTY client includes all the possible tools that may be needed to set up a secure tunnel, and to copy, modify and transfer files.
What an ssh key is used for
The use of an ssh tunnel for a secure connection is algorithmically based on the RSA mathematical mechanism. This cryptographic principle involves the use of two types of keys (ssh keys) – public and private. The «public» key is used to encrypt information and is not secret. The «private» key is intended for decryption. It is held only by the owner of the files and is inaccessible to third parties.
Step-by-step guide on how to connect via SSH
To set up an SSH client and use a secure connection to a Linux server, you can follow this step-by-step guide using the popular PuTTY software as an example:
- Install and launch the PuTTY client application.
- Enter the required connection settings – the server's IP address or hostname.
- Specify the port the server listens on (22 by default).
- If needed, save the specified options.
- Activate the terminal panel, where you will be asked to enter your password and login (account credentials).
To set up an SSH tunnel, use the following guide:
- Using the additional utility puttygen.exe under Windows, generate the «public» and «private» keys for the tunnel.
- Add the «public» key to the server you plan to connect to.
- Add the «private» key to the client application.
- Authenticate when connecting by entering your login and password.
The intuitive graphical interface of the PuTTY client will make setting up the connection and the tunnel much easier for you.
What an ssh tunnel is in a nutshell
The expression ssh tunnel, frequently used in connection with this topic, refers precisely to the secure tunnel that is established for encrypted information transfer between the server and the client, as well as for remote control using SSH technology.
This protective shell, or tunnel, rules out unauthorized interference with the communication session and leaks of passwords and other information.