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SSH

SSH

SSH — is a network protocol for managing servers remotely. Simply put, you can use SSH to manage your server in New York while you are in Australia. The main feature that has made this protocol popular is its security. If the authentication is configured properly, it is almost impossible to hack.

How SSH-connection works

SSH works simply, in accordance with the classic two-component client-server model:

An SSH server, in the form of a software suite, is installed on the remote server to be managed. The SSH server typically listens on port 22.

The SSH client is installed on the computer from which you want to control the SSH server.

Depending on how the SSH Server is configured, the SSH Server accepts incoming connections in one of the following three ways:

  1. By IP address: the SSH server "remembers" the client's IP address and makes the connection if the SSH client's request comes from that address. This connection method is insecure because the IP address can be easily spoofed.
  2. By password: the user sets a password that must be entered each time a connection is made. The password is encrypted, so this connection method is secure.
  3. By key: private and public encryption keys are created. The private or secret key is stored on the SSH client side.

SSH Security

Security is an important benefit of SSH, to which the developers pay a lot of attention. The history of SSH began in 1995 when Finer Jaroham, dissatisfied with the level of security of the Telnet protocol, developed SSH as a replacement for it. Over the years, the protocol has continued to develop tools to protect against SSH hacks. Here are some of the security technologies it has today:

  1. Encryption: SSH uses cryptographic algorithms to protect data transmitted between the client and server. It encrypts all network traffic, including authentication, commands, and data, using symmetric encryption to keep information private.
  2. Authentication: SSH provides client and server authentication to prevent unauthorized access. It provides several authentication methods, including the use of login and password, public key, and X.509 certificates. Public key authentication provides enhanced security by allowing clients to verify the server's identity and prevent man-in-the-middle (MITM) attacks.
  3. SSH uses hashing with algorithms such as SHA-2 to ensure data integrity. This allows it to detect any changes to the data as it travels over the network. If the data has been altered or corrupted, SSH will detect this and terminate the connection to prevent the corrupted data from being used.
  4. Channel creation: SSH can create multiple channels within a single SSH connection, each with its own encryption and authentication parameters. This means that if one channel is attacked or compromised, the other channels remain unaffected.
  5. Audit and logging: SSH logs a list of connections, users, and events so you can detect suspicious activity and prevent attacks.

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