IPFYI
RFC 4253 Proposed Standard

The Secure Shell (SSH) Transport Layer Protocol

T. Ylonen, C. Lonvick · 2006-01

Abstract

The Secure Shell (SSH) is a protocol for secure remote login and other secure network services over an insecure network. This document describes the SSH transport layer protocol, which typically runs on top of TCP/IP. The protocol provides strong encryption, server authentication, and integrity protection.

Why This RFC Matters

RFC 4253 codified the SSH transport layer that replaced plaintext protocols like Telnet and rsh for remote system administration, becoming one of the most widely deployed security protocols in existence. Its negotiation framework — where client and server dynamically agree on key exchange, host key, cipher, MAC, and compression algorithms — allowed SSH to evolve gracefully as cryptographic recommendations changed over time. Nearly every Linux/Unix server, network device, and cloud instance exposes an SSH daemon governed by this specification.

관련 프로토콜

SSH TCP

관련 용어

ssh encryption authentication firewall vpn

Security에서 더 보기

RFC 2404 The Use of HMAC-SHA-1-96 within ESP and AH RFC 3602 The AES-CBC Cipher Algorithm and Its Use with IPsec RFC 4254 The Secure Shell (SSH) Connection Protocol RFC 4301 Security Architecture for the Internet Protocol RFC 5246 The Transport Layer Security (TLS) Protocol Version 1.2 RFC 5280 Internet X.509 Public Key Infrastructure Certificate and CRL Profile RFC 6125 Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS) RFC 6454 The Web Origin Concept