9.1. SSH Transport

9.1 SSH Transport

To run over SSH, the client router first establishes an SSH transport connection using the SSHv2 transport protocol, and the client and server exchange keys for message integrity and encryption. The client then invokes the "ssh-userauth" service to authenticate the application, as described in the SSH authentication protocol [RFC4252]. Once the application has been successfully authenticated, the client invokes the "ssh-connection" service, also known as the SSH connection protocol.

After the ssh-connection service is established, the client opens a channel of type "session", which results in an SSH session.

Once the SSH session has been established, the application invokes the application transport as an SSH subsystem called "rpki-rtr". Subsystem support is a feature of SSHv2 and is not included in SSHv1. Running this protocol as an SSH subsystem avoids the need for the application to recognize shell prompts or skip over extraneous information, such as a system message that is sent at shell startup.

It is assumed that the router and cache have exchanged keys out of band by some reasonably secured means.

Cache servers supporting SSH transport MUST accept RSA authentication and SHOULD accept Elliptic Curve Digital Signature Algorithm (ECDSA) authentication. User authentication MUST be supported; host authentication MAY be supported. Implementations MAY support password authentication. Client routers SHOULD verify the public key of the cache to avoid MITM attacks.