How does SSH tunneling work and how to use local and remote port forwarding instead of a VPN?

SSH tunneling is a powerful network administration tool that allows you to redirect network traffic through an encrypted SSH connection. Instead of installing a full-fledged VPN client, you can use the standard SSH utility, which is present on most operating systems, to create secure tunnels to a remote server, performing the functions of a proxy or VPN without installing additional heavy software.

There are several main types of port forwarding via SSH that are used for various technical tasks. Local port forwarding allows you to redirect a port from your local computer to a remote server through an intermediate node, which is convenient for accessing databases or closed web panels behind a corporate firewall. Remote port forwarding does the reverse, opening access from the external network to a service running on your local computer, which is useful for debugging web applications.

To turn an SSH connection into a full-fledged analogue of a SOCKS5 proxy, the dynamic port forwarding flag is used. In this mode, the SSH client sets up a SOCKS server on the local machine, which accepts any network requests from the browser or applications and wraps them into an encrypted SSH channel to the remote server. This allows you to quickly and securely obtain an encrypted proxy on the fly without the need to administer complex VPN servers.

The main advantages of SSH tunnels are that they do not require installing third-party software on the server, since the SSH server is already running by default on almost any VPS. The connection is initially protected by robust cryptographic algorithms of SSH. However, this approach also has limitations: it is not suitable for continuous background redirection of all system traffic as effectively as specialized VPN clients, and it requires manual reconnection in case of connection drops.