Three layers have different jobs
01SSH combines secure transport, user authentication, and a connection multiplexer.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 1 ↗
RFC 4251 · § 1EXAMPLE
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03
Connection channels
Open shell or forwarding channels under policy.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Original SSH algorithm baselineRFC 9142 § 3
Later transport guidance revises key-exchange recommendations. The 2006 architecture remains useful, but its historical algorithm requirements are not a modern deployment list.
Read the updated RFC section ↗Transport authenticates the server and protects confidentiality and integrity.
- Transport authenticates the server and protects confidentiality and integrity.
- User authentication establishes the client-side user.
- The connection protocol carries logical channels over the protected transport.
The illustration is schematic. Example values are illustrative; profiles and later security guidance can add requirements.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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