11.1. Disconnection Message

      byte      SSH_MSG_DISCONNECT
      uint32    reason code
      string    description in ISO-10646 UTF-8 encoding [RFC3629]
      string    language tag [RFC3066]

This message causes immediate termination of the connection. All implementations MUST be able to process this message; they SHOULD be able to send this message.

The sender MUST NOT send or receive any data after this message, and the recipient MUST NOT accept any data after receiving this message. The Disconnection Message 'description' string gives a more specific explanation in a human-readable form. The Disconnection Message 'reason code' gives the reason in a more machine-readable format (suitable for localization), and can have the values as displayed in the table below. Note that the decimal representation is displayed in this table for readability, but the values are actually uint32 values.

           Symbolic name                                reason code
           -------------                                -----------
      SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT             1
      SSH_DISCONNECT_PROTOCOL_ERROR                          2
      SSH_DISCONNECT_KEY_EXCHANGE_FAILED                     3
      SSH_DISCONNECT_RESERVED                                4
      SSH_DISCONNECT_MAC_ERROR                               5
      SSH_DISCONNECT_COMPRESSION_ERROR                       6
      SSH_DISCONNECT_SERVICE_NOT_AVAILABLE                   7
      SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED          8
      SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE                 9
      SSH_DISCONNECT_CONNECTION_LOST                        10
      SSH_DISCONNECT_BY_APPLICATION                         11
      SSH_DISCONNECT_TOO_MANY_CONNECTIONS                   12
      SSH_DISCONNECT_AUTH_CANCELLED_BY_USER                 13
      SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE         14
      SSH_DISCONNECT_ILLEGAL_USER_NAME                      15

If the 'description' string is displayed, the control character filtering discussed in [SSH-ARCH] should be used to avoid attacks by sending terminal control characters.

Requests for assignments of new Disconnection Message 'reason code' values (and associated 'description' text) in the range of 0x00000010 to 0xFDFFFFFF MUST be done through the IETF CONSENSUS method, as described in [RFC2434]. The Disconnection Message 'reason code' values in the range of 0xFE000000 through 0xFFFFFFFF are reserved for PRIVATE USE. As noted, the actual instructions to the IANA are in [SSH-NUMBERS].

11.1. Disconnection Message​

11.1. Disconnection Message