t.c.s.t.SSHClientTransport(SSHTransportBase) : class documentation

Part of twisted.conch.ssh.transport View Source View In Hierarchy

Known subclasses: twisted.conch.client.direct.SSHClientTransport, twisted.conch.scripts.tkconch.SSHClientTransport

SSHClientTransport implements the client side of the SSH protocol.
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 No summary
Method ssh_KEX_DH_GEX_GROUP This handles two different message which share an integer value.
Method ssh_KEX_DH_GEX_REPLY Called when we receieve a MSG_KEX_DH_GEX_REPLY message. Payload:: string server host key integer f (server DH public key)
Method ssh_NEWKEYS Called when we receieve a MSG_NEWKEYS message. No payload. If we've finished setting up our own keys, start using them. Otherwise, remeber that we've receieved this message.
Method ssh_SERVICE_ACCEPT Called when we receieve a MSG_SERVICE_ACCEPT message. Payload:: string service name
Method requestService Request that a service be run over this transport.
Method verifyHostKey Returns a Deferred that gets a callback if it is a valid key, or an errback if not.
Method connectionSecure Called when the encryption has been set up. Generally, requestService() is called to run another service over the 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.
Method _ssh_KEXDH_REPLY Called to handle a reply to a diffie-hellman-group1-sha1 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:

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 receieved 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 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 connectionLost Called when the connection is shut down.
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 ssh_DISCONNECT Called when we receive a MSG_DISCONNECT message. Payload:: long code string description
Method ssh_IGNORE Called when we receieve a MSG_IGNORE message. No payload. This means nothing; we simply return.
Method ssh_UNIMPLEMENTED Called when we receieve 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 Return True if the connection is encrypted in the given direction. Direction must be one of ["out", "in", "both"].
Method isVerified Return True if the connecction is verified/authenticated in the given direction. Direction must be one of ["out", "in", "both"].
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 completes), _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 _getKey Get one of the keys for authentication/encryption.
Method _newKeys No summary

Inherited from Protocol (via SSHTransportBase):

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

Inherited from BaseProtocol (via SSHTransportBase, Protocol):

Method makeConnection Make a connection to a transport and a server.
isClient =
since we are always the client, this is always True.
_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.
x =
our Diffie-Hellman private key.
e =
our Diffie-Hellman public key.
g =
the Diffie-Hellman group generator.
p =
the Diffie-Hellman group prime
instance =
the SSHService object we are requesting.
def connectionMade(self): (source)
from twisted.internet.interfaces.IProtocol
overrides twisted.conch.ssh.transport.SSHTransportBase.connectionMade
Called when the connection is started with the server. Just sets up a private instance variable.
def ssh_KEXINIT(self, packet): (source)
overrides twisted.conch.ssh.transport.SSHTransportBase.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. If the agreed-upon exchange is diffie-hellman-group1-sha1, generate a public key and send it in a MSG_KEXDH_INIT message. If the exchange is diffie-hellman-group-exchange-sha1, ask for a 2048 bit group with a MSG_KEX_DH_GEX_REQUEST_OLD message.
def _ssh_KEXDH_REPLY(self, packet): (source)
Called to handle a reply to a diffie-hellman-group1-sha1 key exchange message (KEXDH_INIT).

Like the handler for KEXDH_INIT, this message type has an overlapping value. This method is called from ssh_KEX_DH_GEX_GROUP if that method detects a diffie-hellman-group1-sha1 key exchange is in progress.

Payload:

   string serverHostKey
   integer f (server Diffie-Hellman public key)
   string signature

We verify the host key by calling verifyHostKey, then continue in _continueKEXDH_REPLY.

def ssh_KEX_DH_GEX_GROUP(self, packet): (source)
This handles two different message which share an integer value.

If the key exchange is diffie-hellman-group-exchange-sha1, this is MSG_KEX_DH_GEX_GROUP. Payload:

   string g (group generator)
   string p (group prime)

We generate a Diffie-Hellman public key and send it in a MSG_KEX_DH_GEX_INIT message.

def _continueKEXDH_REPLY(self, ignored, pubKey, f, signature): (source)
The host key has been verified, so we generate the keys.
ParameterspubKeythe public key blob for the server's public key. (type: str)
fthe server's Diffie-Hellman public key. (type: long)
signaturethe server's signature, verifying that it has the correct private key. (type: str)
def ssh_KEX_DH_GEX_REPLY(self, packet): (source)
Called when we receieve a MSG_KEX_DH_GEX_REPLY message. Payload:

   string server host key
   integer f (server DH public key)

We verify the host key by calling verifyHostKey, then continue in _continueGEX_REPLY.

def _continueGEX_REPLY(self, ignored, pubKey, f, signature): (source)
The host key has been verified, so we generate the keys.
ParameterspubKeythe public key blob for the server's public key. (type: str)
fthe server's Diffie-Hellman public key. (type: long)
signaturethe server's signature, verifying that it has the correct private key. (type: str)
def _keySetup(self, sharedSecret, exchangeHash): (source)
overrides twisted.conch.ssh.transport.SSHTransportBase._keySetup
See SSHTransportBase._keySetup().
def ssh_NEWKEYS(self, packet): (source)
Called when we receieve a MSG_NEWKEYS message. No payload. If we've finished setting up our own keys, start using them. Otherwise, remeber that we've receieved this message.
def ssh_SERVICE_ACCEPT(self, packet): (source)
Called when we receieve a MSG_SERVICE_ACCEPT message. Payload:

   string service name

Start the service we requested.

def requestService(self, instance): (source)
Request that a service be run over this transport.
def verifyHostKey(self, hostKey, fingerprint): (source)
overridden in twisted.conch.client.direct.SSHClientTransport, twisted.conch.scripts.tkconch.SSHClientTransport
Returns a Deferred that gets a callback if it is a valid key, or an errback if not.
Returns (type: twisted.internet.defer.Deferred)
def connectionSecure(self): (source)
overridden in twisted.conch.client.direct.SSHClientTransport, twisted.conch.scripts.tkconch.SSHClientTransport
Called when the encryption has been set up. Generally, requestService() is called to run another service over the transport.
API Documentation for Twisted, generated by pydoctor at 2012-06-04 17:20:01.