twisted.conch.ssh.transport.SSHClientTransport(SSHTransportBase)
class documentationtwisted.conch.ssh.transport
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Known subclasses: twisted.conch.client.direct.SSHClientTransport, twisted.conch.endpoints._CommandTransport, 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 | 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. |
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. |
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:
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 | connectionLost | When the underlying connection is closed, stop the running service (if any), and log out the avatar (if any). |
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 | _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. |
Called when the connection is started with the server. Just sets up a private instance variable.
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 ECDH, generate a key pair for the corresponding curve and send the public key.
If the agreed-upon exchange has a fixed prime/generator group, generate a public key and send it in a MSG_KEXDH_INIT message. Otherwise, ask for a 2048 bit group with a MSG_KEX_DH_GEX_REQUEST message.
Called to handle a reply to a ECDH exchange message(KEX_ECDH_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 non-group key
exchange is in progress.
Payload:
string serverHostKey string server Elliptic Curve Diffie-Hellman public key string signature
We verify the host key and continue if it passes verificiation. Otherwise raise an exception and return.
Parameters | packet | The message data. (type: bytes ) |
Returns | A deferred firing when key exchange is complete. |
Called to handle a reply to a non-group 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 non-group 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.
Parameters | packet | The message data. (type: bytes ) |
Returns | A deferred firing when key exchange is complete. |
This handles different messages which share an integer value.
If the key exchange does not have a fixed prime/generator group, we generate a Diffie-Hellman public key and send it in a MSG_KEX_DH_GEX_INIT message.
Payload:
string g (group generator) string p (group prime)
Parameters | packet | The message data. (type: bytes ) |
Called when we receive 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.
Parameters | packet | The message data. (type: bytes ) |
Returns | A deferred firing once key exchange is complete. |
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.
Parameters | packet | The message data. (type: bytes ) |
Called when we receive a MSG_SERVICE_ACCEPT message. Payload:
string service name
Start the service we requested.
Parameters | packet | The message data. (type: bytes ) |
Request that a service be run over this transport.
Parameters | instance | The service to run. (type: subclass of twisted.conch.ssh.service.SSHService ) |
Called when the encryption has been set up. Generally, requestService() is called to run another service over the transport.