RFC 8308 · PROPOSED STANDARD · 2018
SUN · 14 JUN 2026
Extension Negotiation in the Secure Shell Protocol
Overview
RFC 8308, “Extension Negotiation in the Secure Shell Protocol”, is a Proposed Standard document published in March 2018 by D. Bider. It updates RFC 4251, RFC 4252, RFC 4253, RFC 4254. It has since been updated by RFC 9519. The canonical text is published by the RFC Editor.
Abstract
This memo updates RFCs 4251, 4252, 4253, and 4254 by defining a mechanism for Secure Shell (SSH) clients and servers to exchange information about supported protocol extensions confidentially after SSH key exchange.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 8308 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 2018
- RFC 8307 Well-Known URIs for the WebSocket Protocol
- RFC 8309 Service Models Explained
- RFC 8310 Usage Profiles for DNS over TLS and DNS over DTLS
- RFC 8311 Relaxing Restrictions on Explicit Congestion Notification Experimentation
- RFC 8304 Transport Features of the User Datagram Protocol and Lightweight UDP
- RFC 8312 CUBIC for Fast Long-Distance Networks
- RFC 8303 On the Usage of Transport Features Provided by IETF Transport Protocols
- RFC 8313 Use of Multicast across Inter-domain Peering Points