2. Architecture and basic operation

2.1 SSH subprotocols

SSH uses a client-server architecture to ensure authentication of communicating entities, and encryption and integrity of their data transmitted over a network. As already mentioned, version 2 of this protocol specifies an architecture separated into three sub-protocols (or layers) working together, as shown in figure 1 :

• SSH transport layer (SSH-TRANS)

  The other two SSH layers are based on this layer. SSH-TRANS provides server authentication, confidentiality and data integrity using symmetrical encryption (see...