While it is closely linked with the private key in terms of functionality, the private key cannot be mathematically computed from the public key.

The service was created as a secure replacement for the unencrypted Telnet and uses cryptographic techniques to ensure that all communication to and from the remote server happens in an encrypted manner.

It provides a mechanism for authenticating a remote user, transferring inputs from the client to the host, and relaying the output back to the client.

Any Linux or macOS user can SSH into their remote server directly from the terminal window.

You can execute shell commands in the same manner as you would if you were physically operating the remote computer.

If you use Windows, you will need to utilize an SSH client to open SSH connections.

The most popular SSH client is PuTTY, which you can learn more about here.

For example, you may want to access the root user, which is basically synonymous for system administrator with complete rights to modify anything on the system.

When you type it in, nothing will appear on the screen, but your password is, in fact being transmitted.

Host refers to the remote server you are trying to access, while the client is the computer you are using to access the host.

There are three different encryption technologies used by SSH.

Effectively, any one possessing the key can decrypt the message being transferred.

There is usually only one key that is used, or sometimes a pair keys where one key can easily be calculated using the other key.

Both the client and the server derive the secret key using an agreed method, and the resultant key is never disclosed to any third party.

The process of creating a symmetric key is carried out by a key exchange algorithm.

What makes this algorithm particularly secure is the fact that the key is never transmitted between the client and the host.

Instead, the two computers share public pieces of data and then manipulate it to independently calculate the secret key.

Even if another machine captures the publically shared data, it wont be able to calculate the key because the key exchange algorithm is not known.

Once the key has been generated, all packets moving between the two machines must be encrypted by the private key.

This includes the password typed into the console by the user, so credentials are always protected from network packet sniffers.

Before establishing a secured connection, the client and a host decide upon which cipher to use, by publishing a list of supported cyphers in order of preference.

The most preferred cypher from the clients supported cyphers that is present on the hosts list is used as the bidirectional cypher.

These two keys are known as the public key and the private key.

Ssh Access For Mac