SSH Protocol (Secure Shell) is a cryptographic network protocol designed for secure remote computer management and data transmission over unsecured networks. SSH provides encrypted connection between client and server, replacing insecure protocols such as Telnet and ensuring confidentiality and integrity of service information.
SSH operates based on client-server model, where SSH client initiates connection with SSH server, usually running on port 22. The protocol uses asymmetric encryption for initial connection processing and authentication, then switches to symmetric encryption to ensure high data transmission performance.
Authentication Methods
SSH supports several user authentication protocols. Password authentication remains the most common but less secure option. Key-based authentication uses cryptographic key pairs and is considered more reliable. Additional methods are available based on Kerberos certificates and two-factor authentication.
Main Capabilities
The protocol provides remote access to command line systems, allowing administrators to execute commands as if they were working locally. SSH ensures secure file transfer through SCP and SFTP protocols, tunneling traffic of other applications and port forwarding to provide secure access to distributed services.
Modern SSH implementations provide reliable encryption algorithms, AES, ChaCha20 and various elliptic cryptography variants. Cryptographic hash functions SHA-2 and HMAC are applied for data provision. Key agreement algorithms allow ensuring secure cryptographic key exchange.
Practical Application
SSH is widely used by system administrators for server and network equipment management, by developers for application deployment and access to remote development environments. The solution is indispensable when working with cloud infrastructures where secure connection to virtual machines and containers is required.
Proper SSH configuration includes disabling password authentication for privileged accounts, using non-standard ports, restricting access by IP addresses and implementing password complexity policies. Regular updating of SSH servers and clients is extremely important for protection against known vulnerabilities.
Despite the emergence of new remote access protocols, SSH de facto remains the main standard due to extended support, reliability and time-tested security. The modern protocol version continues to build power, adding support for new cryptographic algorithms and improving performance.