SSH Proxy Tunnels

Instructor: Lyna Griffin

Lyna has tutored undergraduate Information Management Systems and Database Development. She has a Bachelor's degree in Electrical Engineering and a Masters degree in Information Technology.

In this lesson, we will examine what proxy tunneling is all about and understand what SSH proxy tunneling is. We will examine the three main uses of SSH proxy tunnels.

What Is SSH Proxy Tunneling?

Imagine you are in a group of people sitting at a round table. Everyone speaks the same language - English (open connections). Simultaneous conversations are going on across the table (data transmissions). Anything that is said could be overheard, listened to, repeated or stolen (vulnerable data) from and by anyone present or in close proximity to the round table. Your conversation is not secure! You can decide to speak in another language hoping others do not understand (encryption). It is somewhat secure, but definitely not guaranteed. You go a step further and use a private telephone line (secure tunnel ) and have a better secured private conversation across the table. With the telephone, even though you may be speaking in English (unencrypted data), no one can have access to or hear or eavesdrop on your conversation. Your conversation is much more secure.

Today, technology has taken over almost everything and digital communications are employed in every facet of our lives. As much as the internet has become the giant that it is, for our communications, it is also a source of great peril because of its security risks. Communication transmissions are therefore done within various secure environments. One such environment is the SSH tunnel. SSH (Secure shell) Proxy tunneling is an encrypted tunnel that is created to allow data transmissions through a secure SSH protocol between devices over a network. This means that traffic which are unencrypted (like the English conversation) are given safe and secure passages (telephone connection) to their respective destinations.

SSH Tunneling Illustrated

Let us consider a daily activity like checking our emails. This activity involves our computer (client) accessing an email server (server) through our network connection (internet) with the transmission and remission of emails (data transmissions) in between. The client is verified through a system of encryption keys (like private telephone numbers exchanged) and a secure tunnel established (call goes through) after successful verification.

To recap, SSH is therefore a network protocol that provides a secure tunnel for data that is being transmitted between a client and a server over a public network (internet). This is illustrated in the following diagram.

ssh tunnel

SSH Applications

Numerous data transmissions are done per second by millions of users on the internet daily. Therefore, there are many methods of securing these data transmissions. We will look at the following SSH applications.

Encrypted File Transfers

The internet provides the largest medium for file transfer. Internet connections facilitate file access, transfers and file management as a whole. An e-learning establishment, for example, may have cause to frequently transit large files between students and tutors as work, notes and lessons are distributed daily. Even though unsecured file transfer protocols may be established, the SSH provides a secure tunnel through which these transmissions take place.

Secure Command Shell

Another important use of SSH tunneling is the transmission of administrative commands. Remote administration has become an invaluable tool to both system administrators and users. Has a system administrator who is not within your geographical location ever taken control of your client machine and sorted something out? If so, then you have experienced remote administration. In the execution of remote administration by system administrators from remote locations, system commands and programs, such as shutdown, startup, updates and installations, are executed through the secure encrypted tunnels provided by SSH on remote client machines and servers.

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