RFCs

Interesting RFCs

First RFC (7 April 1969): https://tools.ietf.org/html/rfc1
RFC Key word ("MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"): <https://tools.ietf.org/html/rfc
Choosing a Name for Your Computer: https://www.rfc-editor.org/rfc/rfc1178

Specification	Description
RFC4250	SSH Protocol Assigned Numbers
RFC4251	SSH Protocol Architecture
RFC4252	SSH Authentication Protocol
RFC4253	SSH Transport Layer Protocol
RFC4254	SSH Connection Protocol

Specification	Versions	Description
RFC4255		Using DNS to Securely Publish SSH Key Fingerprints (SSHFP)
RFC4256		Generic Message Exchange Authentication (aka keyboard-interactive)
RFC4335		SSH Session Channel Break Extension
RFC4344		SSH Transport Layer Encryption Modes (aes128-ctr, aes192-ctr, aes256-ctr)
RFC4345	4.1-7.6	Improved Arcfour Modes for the SSH Transport Layer Protocol
RFC4419		Diffie-Hellman Group Exchange
RFC4462		GSS-API Authentication and Key Exchange (only authentication implemented)
RFC4716		SSH Public Key File Format (import and export via ssh-keygen only).
RFC5656		Elliptic Curve Algorithm Integration in SSH
RFC6594	6.1-	SHA-256 SSHFP Resource Records
RFC6668	5.9-	SHA-2 Data Integrity Algorithms (hmac-sha2-256, hmac-sha2-512)
RFC7479	6.5-	ED25519 SSHFP Resource Records
RFC8160	7.3-	IUTF8 Terminal Mode
RFC8270	7.1-	Increase Diffie-Hellman Modulus Size
RFC8308	7.2-	Extension Negotiation in the Secure Shell (SSH) Protocol (ext-info-s, ext-info-c)
RFC8332	7.2-	Use of RSA Keys with SHA-2 (rsa-sha2-256, rsa-sha2-512)
RFC8709	6.5-	Ed25519 and Ed448 Public Key Algorithms (ssh-ed25519 only)
RFC8731	7.3-	Key Exchange Method Using Curve25519 and Curve448 (curve25519-sha256 only)

Specification	Description
RFC1928	SOCKS protocol version 5. Used for ssh(1) DynamicForward.
RFC1349, RFC8325	IP Type of Service (ToS) and Differentiated Services. OpenSSH will automatically set the IP Type of Service according to RFC8325 unless otherwise specified via the IPQoS keyword in ssh_config and sshd_config. Versions 7.7 and earlier will set it per rfc1349 unless otherwise specified.