Esse é o código de razão para a desconexão. De a fonte :
/* disconnect reason code */
#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1
#define SSH2_DISCONNECT_PROTOCOL_ERROR 2
#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED 3
#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4
#define SSH2_DISCONNECT_RESERVED 4
#define SSH2_DISCONNECT_MAC_ERROR 5
#define SSH2_DISCONNECT_COMPRESSION_ERROR 6
#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE 7
#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8
#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9
#define SSH2_DISCONNECT_CONNECTION_LOST 10
#define SSH2_DISCONNECT_BY_APPLICATION 11
#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS 12
#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER 13
#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14
#define SSH2_DISCONNECT_ILLEGAL_USER_NAME 15