twisted.conch.endpoints._CommandTransport(SSHClientTransport) class documentation

Part of twisted.conch.endpoints (View In Hierarchy)

_CommandTransport is an SSH client transport which includes a host key verification step before it will proceed to secure the connection.

_CommandTransport also knows how to set up a connection to an authentication agent if it is told where it can connect to one.

Method __init__
Method verifyHostKey Ask the KnownHostsFile provider available on the factory which created this protocol this protocol to verify the given host key.
Method connectionSecure When the connection is secure, start the authentication process.
Method connectionLost When the underlying connection to the SSH server is lost, if there were any connection setup errors, propagate them. Also, clean up the connection to the ssh agent if one was created.
Instance Variable _userauth The _UserAuth instance which is in charge of the overall authentication process or None if the SSH connection has not reach yet the user-auth service. (type: _UserAuth)
Method _saveHostKeyFailure When host key verification fails, record the reason for the failure in order to fire a Deferred with it later.

Inherited from SSHClientTransport:

Instance Variable isClient since we are always the client, this is always True.
Instance Variable x our Diffie-Hellman private key.
Instance Variable e our Diffie-Hellman public key.
Instance Variable g the Diffie-Hellman group generator.
Instance Variable p the Diffie-Hellman group prime
Instance Variable instance the SSHService object we are requesting.
Method connectionMade Called when the connection is started with the server. Just sets up a private instance variable.
Method ssh_KEXINIT Called when we receive a MSG_KEXINIT message. For a description of the packet, see SSHTransportBase.ssh_KEXINIT(). Additionally, this method sends the first key exchange packet.
Method ssh_KEX_DH_GEX_GROUP This handles different messages which share an integer value.
Method ssh_KEX_DH_GEX_REPLY Called when we receive a MSG_KEX_DH_GEX_REPLY message. Payload:: string server host key integer f (server DH public key)
Method ssh_NEWKEYS Called when we receive a MSG_NEWKEYS message. No payload. If we've finished setting up our own keys, start using them. Otherwise, remember that we've received this message.
Method ssh_SERVICE_ACCEPT Called when we receive a MSG_SERVICE_ACCEPT message. Payload:: string service name
Method requestService Request that a service be run over this transport.
Instance Variable _gotNewKeys if we receive a MSG_NEWKEYS message before we are ready to transition to the new keys, this is set to True so we can transition when the keys are ready locally.
Instance Variable _dhMinimalGroupSize Minimal acceptable group size advertised by the client in MSG_KEX_DH_GEX_REQUEST. (type: int)
Instance Variable _dhMaximalGroupSize Maximal acceptable group size advertised by the client in MSG_KEX_DH_GEX_REQUEST. (type: int)
Instance Variable _dhPreferredGroupSize Preferred group size advertised by the client in MSG_KEX_DH_GEX_REQUEST. (type: int)
Method _ssh_KEX_ECDH_REPLY Called to handle a reply to a ECDH exchange message(KEX_ECDH_INIT).
Method _ssh_KEXDH_REPLY Called to handle a reply to a non-group key exchange message (KEXDH_INIT).
Method _continueKEXDH_REPLY The host key has been verified, so we generate the keys.
Method _continueGEX_REPLY The host key has been verified, so we generate the keys.
Method _keySetup See SSHTransportBase._keySetup().

Inherited from SSHTransportBase (via SSHClientTransport):

Instance Variable protocolVersion A string representing the version of the SSH protocol we support. Currently defaults to '2.0'.
Instance Variable version A string representing the version of the server or client. Currently defaults to 'Twisted'.
Instance Variable comment An optional string giving more information about the server or client.
Instance Variable supportedCiphers A list of strings representing the encryption algorithms supported, in order from most-preferred to least.
Instance Variable supportedMACs A list of strings representing the message authentication codes (hashes) supported, in order from most-preferred to least. Both this and supportedCiphers can include 'none' to use no encryption or authentication, but that must be done manually,
Instance Variable supportedKeyExchanges A list of strings representing the key exchanges supported, in order from most-preferred to least.
Instance Variable supportedPublicKeys A list of strings representing the public key types supported, in order from most-preferred to least.
Instance Variable supportedCompressions A list of strings representing compression types supported, from most-preferred to least.
Instance Variable supportedLanguages A list of strings representing languages supported, from most-preferred to least.
Instance Variable supportedVersions A container of strings representing supported ssh protocol version numbers.
Instance Variable gotVersion A boolean indicating whether we have received the version string from the other side.
Instance Variable buf Data we've received but hasn't been parsed into a packet.
Instance Variable outgoingPacketSequence the sequence number of the next packet we will send.
Instance Variable incomingPacketSequence the sequence number of the next packet we are expecting from the other side.
Instance Variable outgoingCompression an object supporting the .compress(str) and .flush() methods, or None if there is no outgoing compression. Used to compress outgoing data.
Instance Variable outgoingCompressionType A string representing the outgoing compression type.
Instance Variable incomingCompression an object supporting the .decompress(str) method, or None if there is no incoming compression. Used to decompress incoming data.
Instance Variable incomingCompressionType A string representing the incoming compression type.
Instance Variable ourVersionString the version string that we sent to the other side. Used in the key exchange.
Instance Variable otherVersionString the version string sent by the other side. Used in the key exchange.
Instance Variable ourKexInitPayload the MSG_KEXINIT payload we sent. Used in the key exchange.
Instance Variable otherKexInitPayload the MSG_KEXINIT payload we received. Used in the key exchange
Instance Variable sessionID a string that is unique to this SSH session. Created as part of the key exchange, sessionID is used to generate the various encryption and authentication keys.
Instance Variable service an SSHService instance, or None. If it's set to an object, it's the currently running service.
Instance Variable kexAlg 0 the agreed-upon key exchange algorithm.
Instance Variable keyAlg the agreed-upon public key type for the key exchange.
Instance Variable currentEncryptions an SSHCiphers instance. It represents the current encryption and authentication options for the transport.
Instance Variable nextEncryptions an SSHCiphers instance. Held here until the MSG_NEWKEYS messages are exchanged, when nextEncryptions is transitioned to currentEncryptions.
Instance Variable first the first bytes of the next packet. In order to avoid decrypting data twice, the first bytes are decrypted and stored until the whole packet is available.
Method sendKexInit Send a KEXINIT message to initiate key exchange or to respond to a key exchange initiated by the peer.
Method sendPacket Sends a packet. If it's been set up, compress the data, encrypt it, and authenticate it before sending. If key exchange is in progress and the message is not part of key exchange, queue it to be sent later.
Method getPacket Try to return a decrypted, authenticated, and decompressed packet out of the buffer. If there is not enough data, return None.
Method dataReceived First, check for the version string (SSH-2.0-*). After that has been received, this method adds data to the buffer, and pulls out any packets.
Method dispatchMessage Send a received message to the appropriate method.
Method getPeer Returns an SSHTransportAddress corresponding to the other (peer) side of this transport.
Method getHost Returns an SSHTransportAddress corresponding to the this side of transport.
Method kexAlg 1 The key exchange algorithm name agreed between client and server.
Method kexAlg Set the key exchange algorithm name.
Method ssh_DISCONNECT Called when we receive a MSG_DISCONNECT message. Payload:: long code string description
Method ssh_IGNORE Called when we receive a MSG_IGNORE message. No payload. This means nothing; we simply return.
Method ssh_UNIMPLEMENTED Called when we receive a MSG_UNIMPLEMENTED message. Payload:: long packet
Method ssh_DEBUG No summary
Method setService Set our service to service and start it running. If we were running a service previously, stop it first.
Method sendDebug Send a debug message to the other side.
Method sendIgnore Send a message that will be ignored by the other side. This is useful to fool attacks based on guessing packet sizes in the encrypted stream.
Method sendUnimplemented Send a message to the other side that the last packet was not understood.
Method sendDisconnect Send a disconnect message to the other side and then disconnect.
Method isEncrypted Check if the connection is encrypted in the given direction.
Method isVerified Check if the connection is verified/authentication in the given direction.
Method loseConnection Lose the connection to the other side, sending a DISCONNECT_CONNECTION_LOST message.
Method receiveError Called when we receive a disconnect error message from the other side.
Method receiveUnimplemented Called when we receive an unimplemented packet message from the other side.
Method receiveDebug Called when we receive a debug message from the other side.
Instance Variable _keyExchangeState The current protocol state with respect to key exchange. This is either _KEY_EXCHANGE_NONE if no key exchange is in progress (and returns to this value after any key exchange completqes), _KEY_EXCHANGE_REQUESTED if this side of the connection initiated a key exchange, and _KEY_EXCHANGE_PROGRESSING if the other side of the connection initiated a key exchange. _KEY_EXCHANGE_NONE is the initial value (however SSH connections begin with key exchange, so it will quickly change to another state).
Instance Variable _blockedByKeyExchange Whenever _keyExchangeState is not _KEY_EXCHANGE_NONE, this is a list of pending messages which were passed to sendPacket but could not be sent because it is not legal to send them while a key exchange is in progress. When the key exchange completes, another attempt is made to send these messages.
Method _allowedKeyExchangeMessageType Determine if the given message type may be sent while key exchange is in progress.
Method _unsupportedVersionReceived Called when an unsupported version of the ssh protocol is received from the remote endpoint.
Method _startEphemeralDH Prepares for a Diffie-Hellman key agreement exchange.
Method _finishEphemeralDH Completes the Diffie-Hellman key agreement started by _startEphemeralDH, and forgets the ephemeral secret key.
Method _getKey Get one of the keys for authentication/encryption.
Method _newKeys No summary
Method _generateECPrivateKey Generate an private key for ECDH key exchange.
Method _encodeECPublicKey Encode an elliptic curve public key to bytes.
Method _generateECSharedSecret Generate a shared secret for ECDH key exchange.

Inherited from Protocol (via SSHClientTransport, SSHTransportBase):

Method logPrefix Return a prefix matching the class name, to identify log messages related to this protocol instance.

Inherited from BaseProtocol (via SSHClientTransport, SSHTransportBase, Protocol):

Method makeConnection Make a connection to a transport and a server.
_userauth =
The _UserAuth instance which is in charge of the overall authentication process or None if the SSH connection has not reach yet the user-auth service. (type: _UserAuth)
def __init__(self, creator):
ParameterscreatorThe _NewConnectionHelper that created this connection. (type: _NewConnectionHelper.)
def verifyHostKey(self, hostKey, fingerprint):
overrides twisted.conch.ssh.transport.SSHClientTransport.verifyHostKey

Ask the KnownHostsFile provider available on the factory which created this protocol this protocol to verify the given host key.

ReturnsA Deferred which fires with the result of KnownHostsFile.verifyHostKey.
def _saveHostKeyFailure(self, reason):

When host key verification fails, record the reason for the failure in order to fire a Deferred with it later.

ParametersreasonThe cause of the host key verification failure. (type: Failure)
Returnsreason (type: Failure)
def connectionSecure(self):
overrides twisted.conch.ssh.transport.SSHClientTransport.connectionSecure

When the connection is secure, start the authentication process.

def connectionLost(self, reason):
from twisted.internet.interfaces.IProtocol
overrides twisted.conch.ssh.transport.SSHTransportBase.connectionLost

When the underlying connection to the SSH server is lost, if there were any connection setup errors, propagate them. Also, clean up the connection to the ssh agent if one was created.

API Documentation for twisted, generated by pydoctor at 2020-03-25 17:34:30.