SSHServer Class

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The SSHServer class is used to create Secure Shell (SSH) servers. The class handles multiple simultaneous connections on the same TCP/IP port (service port). It is designed to balance the load between connections for a fast, powerful server.

Syntax

class ipworksssh.SSHServer

Remarks

The SSHServer class is the SSH-enabled equivalent of the IPWorks TCPServer class, extended by a set of new properties and events that deal with SSH security. The ssh_compression_algorithms and ssh_encryption_algorithms properties determine which protocols are enabled for the SSH handshake. The ssh_cert* properties are used to select a certificate for the server (please note that a valid certificate MUST be selected before the server can function). The on_ssh_user_auth_request event will allow you to use authenticate clients using digital certificates or passwords. Finally, the on_ssh_status event provides information about the SSH handshake and underlying protocol notifications.

By default, each instance of SSHServer can handle up to 1000 simultaneous incoming connections (this number may be increased up to 100,000, or decreased to a lower value by using the MaxConnections configuration setting).

SSH connections are identified by a ConnectionId. Events relating to these connections as a whole will use the ConnectionId to identify the specific connection. Connections may also contained one or more multiplexed channels, which are identified by a ChannelId. Channel-level events will specify the ChannelId to which they relate.

SSHServer can start to listen on a port by setting the listening property to True. When a remote host asks for a connection, the on_connection_request event is fired. At that point, the connection can either be accepted or rejected. If the connection is accepted, a ConnectionId is assigned, and communication can start. From this point on, the operation is very similar to SSHClient. Data can be sent to an individual SSHChannel using send_channel_data. The address and port of the incoming connection can be found by querying the client_remote_host and client_remote_port properties.

Note: Server components are designed to process events as they occur. To ensure that events are processed in a timely manner, do_events should be called in a loop after the server is started.

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.

ssh_channel_count Property

The number of records in the arrays.

Syntax

def get_ssh_channel_count() -> int: ...

ssh_channel_count = property(get_ssh_channel_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• bytes_sent
• channel_id
• data_to_send
• keyboard_interactive_prompt_echo
• keyboard_interactive_prompt_prompt
• ready_to_send
• record_length
• service
• ssh_cert_encoded
• ssh_cert_store
• ssh_cert_store_password
• ssh_cert_store_type
• ssh_cert_subject
• ssh_connection_connected
• ssh_connection_local_address
• ssh_connection_remote_host
• ssh_connection_remote_port
• ssh_connection_timeout

The array indices start at 0 and end at ssh_channel_count - 1.

This property is read-only.

bytes_sent Property

The number of bytes actually sent after a sending channel data.

Syntax

def get_bytes_sent(ssh_channel_id: int) -> int: ...

Default Value

0

Remarks

The number of bytes actually sent after a sending channel data.

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

This property is read-only.

channel_id Property

An id generated by the class to identify the current SSH channel.

Syntax

def get_channel_id(ssh_channel_id: int) -> str: ...

Default Value

""

Remarks

An id generated by the class to identify the current SSH channel. This id is unique to this channel.

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

This property is read-only.

data_to_send Property

A string of data to be sent to the remote host.

Syntax

def set_data_to_send(ssh_channel_id: int, value: bytes) -> None: ...

Default Value

""

Remarks

A string of data to be sent to the remote host. Write-only property.

Assigning a string to the datatosend makes the class send the string to the remote host.

Note:It is recommended to use the sendtext or sendbytes method instead of setting this property.

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

This property is write-only.

ready_to_send Property

This property is True when data can be sent over the SSH Channel.

Syntax

def get_ready_to_send(ssh_channel_id: int) -> bool: ...

Default Value

FALSE

Remarks

This property is True when data can be sent over the SSH Channel.

When timeout is set to 0 (asynchronous) sending data may result in an error if the channel or underlying socket cannot accept more data to send. Monitor onsshchannelreadytosend or readytosend to determine when data can be sent again.

When timeout is set to a positive value the class will block when sending data until the data can be successfully sent and onsshchannelreadytosend and readytosend do not need to be monitored.

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

This property is read-only.

record_length Property

The length of received data records.

Syntax

def get_record_length(ssh_channel_id: int) -> int: ...
def set_record_length(ssh_channel_id: int, value: int) -> None: ...

Default Value

0

Remarks

The length of received data records. If set to a positive value, this setting defines the length of data records to be received. The class will accumulate data until RecordLength is reached and only then fire the onsshchanneldatain event with data of length RecordLength. This allows data to be received as records of known length. This value can be changed at any time, including within the onsshchanneldatain event.

The default value is 0, meaning this setting is not used.

Note:It is recommended to use the changerecordlength method instead of setting this property.

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

service Property

This property holds the channel type that was requested when opening the channel.

Syntax

def get_service(ssh_channel_id: int) -> str: ...

Default Value

""

Remarks

This property holds the channel type that was requested when opening the channel. For instance "session" or "forwarded-tcpip".

The ssh_channel_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_channel_count property.

This property is read-only.

connection_backlog Property

This property includes the maximum number of pending connections maintained by the Transmission Control Protocol (TCP)/IP subsystem.

Syntax

def get_connection_backlog() -> int: ...
def set_connection_backlog(value: int) -> None: ...

connection_backlog = property(get_connection_backlog, set_connection_backlog)

Default Value

5

Remarks

This property contains the maximum number of pending connections maintained by the TCP/IP subsystem. This value reflects the SOMAXCONN option for the main listening socket. The default value for most systems is 5. You may set this property to a larger value if the server is expected to receive a large number of connections, and queuing them is desirable.

ssh_connection_count Property

The number of records in the SSHConnection arrays.

Syntax

def get_ssh_connection_count() -> int: ...

ssh_connection_count = property(get_ssh_connection_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• ssh_connection_connected
• ssh_connection_local_address
• ssh_connection_remote_host
• ssh_connection_remote_port
• ssh_connection_timeout

The array indices start at 0 and end at ssh_connection_count - 1.

This property is read-only.

ssh_connection_connected Property

Used to disconnect individual connections and/or show their status.

Syntax

def get_ssh_connection_connected(connection_id: int) -> bool: ...
def set_ssh_connection_connected(connection_id: int, value: bool) -> None: ...

Default Value

FALSE

Remarks

Used to disconnect individual connections and/or show their status.

The connected is used to close connections.

connected also shows the status of a particular connection (connected/disconnected).

How and when the connection is closed is controlled by the linger property. Please refer to its description for more information.

Note:It is recommended to use the disconnect method instead of setting this property.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_connection_count property.

ssh_connection_local_address Property

This property shows the IP address of the interface through which the connection is passing.

Syntax

def get_ssh_connection_local_address(connection_id: int) -> str: ...

Default Value

""

Remarks

This property shows the IP address of the interface through which the connection is passing.

localaddress is important for multihomed hosts where it can be used to find which particular network interface an individual connection is going through.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_connection_count property.

This property is read-only.

ssh_connection_remote_host Property

The RemoteHost shows the IP address of the remote host through which the connection is coming.

Syntax

def get_ssh_connection_remote_host(connection_id: int) -> str: ...

Default Value

""

Remarks

The remotehost shows the IP address of the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

If the class is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_connection_count property.

This property is read-only.

ssh_connection_remote_port Property

The RemotePort shows the TCP port on the remote host through which the connection is coming.

Syntax

def get_ssh_connection_remote_port(connection_id: int) -> int: ...

Default Value

0

Remarks

The remoteport shows the TCP port on the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_connection_count property.

This property is read-only.

ssh_connection_timeout Property

A timeout for the class.

Syntax

def get_ssh_connection_timeout(connection_id: int) -> int: ...
def set_ssh_connection_timeout(connection_id: int, value: int) -> None: ...

Default Value

0

Remarks

A timeout for the class.

If the timeout property is set to 0, all operations return immediately, potentially failing with an 'WOULDBLOCK' error if data can't be sent or received immediately.

If timeout is set to a positive value, the class will automatically retry each operation that would otherwise result in a 'WOULDBLOCK' error for a maximum of timeout seconds.

The class will use doevents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If timeout expires, and the operation is not yet complete, the class fails with an error.

Please note that by default, all timeouts are inactivity timeouts, i.e. the timeout period is extended by timeout seconds when any amount of data is successfully sent or received.

The default value for the timeout property is 0 (asynchronous operation).

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the ssh_connection_count property.

default_auth_methods Property

Specifies the supported authentication methods.

Syntax

def get_default_auth_methods() -> str: ...
def set_default_auth_methods(value: str) -> None: ...

default_auth_methods = property(get_default_auth_methods, set_default_auth_methods)

Default Value

"password,publickey"

Remarks

This property specifies the supported authentication methods. The client will choose one of the supported mechanisms when authenticating to the class.

This must be a comma separated list of values. For more information on authenticating clients see the on_ssh_user_auth_request event.

The following is a list of methods implemented by the class:

default_idle_timeout Property

This property includes the default idle timeout for inactive clients.

Syntax

def get_default_idle_timeout() -> int: ...
def set_default_idle_timeout(value: int) -> None: ...

default_idle_timeout = property(get_default_idle_timeout, set_default_idle_timeout)

Default Value

0

Remarks

This property specifies the idle timeout (in seconds) for clients. When set to a positive value, the class will disconnect idle clients after the specified timeout.

This applies only to clients that have not sent or received data within default_idle_timeout seconds.

If set to 0 (default), no idle timeout is applied.

Note: do_events must be called for the class to check existing connections.

default_timeout Property

An initial timeout value to be used by incoming connections.

Syntax

def get_default_timeout() -> int: ...
def set_default_timeout(value: int) -> None: ...

default_timeout = property(get_default_timeout, set_default_timeout)

Default Value

60

Remarks

This property is used by the class to set the operational timeout value of all inbound connections once they are established. If the timeout is set to 0, all inbound connections will behave asynchronously. The default value is 60, meaning the class will behave synchronously.

keyboard_interactive_message Property

The instructions to send to the client during keyboard-interactive authentication.

Syntax

def get_keyboard_interactive_message() -> str: ...
def set_keyboard_interactive_message(value: str) -> None: ...

keyboard_interactive_message = property(get_keyboard_interactive_message, set_keyboard_interactive_message)

Default Value

""

Remarks

This property should be set to the main instructions to send to the client during keyboard-interactive authentication.

keyboard_interactive_prompt_count Property

The number of records in the KeyboardInteractivePrompt arrays.

Syntax

def get_keyboard_interactive_prompt_count() -> int: ...
def set_keyboard_interactive_prompt_count(value: int) -> None: ...

keyboard_interactive_prompt_count = property(get_keyboard_interactive_prompt_count, set_keyboard_interactive_prompt_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• keyboard_interactive_prompt_echo
• keyboard_interactive_prompt_prompt

The array indices start at 0 and end at keyboard_interactive_prompt_count - 1.

keyboard_interactive_prompt_echo Property

Specifies if the client should echo the value entered by the user or not.

Syntax

def get_keyboard_interactive_prompt_echo(prompt_index: int) -> bool: ...
def set_keyboard_interactive_prompt_echo(prompt_index: int, value: bool) -> None: ...

Default Value

FALSE

Remarks

Specifies if the client should echo the value entered by the user or not.

The prompt_index parameter specifies the index of the item in the array. The size of the array is controlled by the keyboard_interactive_prompt_count property.

keyboard_interactive_prompt_prompt Property

The prompt label/text the client should present to the user.

Syntax

def get_keyboard_interactive_prompt_prompt(prompt_index: int) -> str: ...
def set_keyboard_interactive_prompt_prompt(prompt_index: int, value: str) -> None: ...

Default Value

""

Remarks

The prompt label/text the client should present to the user.

The prompt_index parameter specifies the index of the item in the array. The size of the array is controlled by the keyboard_interactive_prompt_count property.

listening Property

If set to True, the class accepts incoming connections on LocalPort.

Syntax

def get_listening() -> bool: ...
def set_listening(value: bool) -> None: ...

listening = property(get_listening, set_listening)

Default Value

FALSE

Remarks

This property indicates whether the class is listening for connections on the port specified by the local_port property.

Note: Use the start_listening and stop_listening methods to control whether the class is listening.

local_host Property

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

def get_local_host() -> str: ...
def set_local_host(value: str) -> None: ...

local_host = property(get_local_host, set_local_host)

Default Value

""

Remarks

The local_host property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.

If the class is connected, the local_host property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: local_host is not persistent. You must always set it in code, and never in the property window.

local_port Property

The TCP port in the local host where the class listens.

Syntax

def get_local_port() -> int: ...
def set_local_port(value: int) -> None: ...

local_port = property(get_local_port, set_local_port)

Default Value

22

Remarks

The local_port property must be set before TCPServer starts listening. If its value is 0, then the TCP/IP subsystem picks a port number at random. The port number can be found by checking the value of the local_port property after TCPServer is in listening mode (after successfully assigning True to the listening property).

The service port is not shared among servers (i.e. there can be only one TCPServer 'listening' on a particular port at one time).

ssh_cert_encoded Property

This is the certificate (PEM/base64 encoded).

Syntax

def get_ssh_cert_encoded() -> bytes: ...
def set_ssh_cert_encoded(value: bytes) -> None: ...

ssh_cert_encoded = property(get_ssh_cert_encoded, set_ssh_cert_encoded)

Default Value

""

Remarks

This is the certificate (PEM/base64 encoded). This property is used to assign a specific certificate. The store and subject properties also may be used to specify a certificate.

When encoded is set, a search is initiated in the current store for the private key of the certificate. If the key is found, subject is updated to reflect the full subject of the selected certificate; otherwise, subject is set to an empty string.

ssh_cert_store Property

This is the name of the certificate store for the client certificate.

Syntax

def get_ssh_cert_store() -> bytes: ...
def set_ssh_cert_store(value: bytes) -> None: ...

ssh_cert_store = property(get_ssh_cert_store, set_ssh_cert_store)

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The storetype property denotes the type of the certificate store specified by store. If the store is password protected, specify the password in storepassword.

store is used in conjunction with the subject property to specify client certificates. If store has a value, and subject or encoded is set, a search for a certificate is initiated. Please see the subject property for details.

Designations of certificate stores are platform-dependent.

The following are designations of the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e. PKCS12 certificate store).

ssh_cert_store_password Property

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

def get_ssh_cert_store_password() -> str: ...
def set_ssh_cert_store_password(value: str) -> None: ...

ssh_cert_store_password = property(get_ssh_cert_store_password, set_ssh_cert_store_password)

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

ssh_cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

def get_ssh_cert_store_type() -> int: ...
def set_ssh_cert_store_type(value: int) -> None: ...

ssh_cert_store_type = property(get_ssh_cert_store_type, set_ssh_cert_store_type)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The class supports both public and private keys in a variety of formats. When the cstAuto value is used the class will automatically determine the type. This property can take one of the following values:

ssh_cert_subject Property

This is the subject of the certificate used for client authentication.

Syntax

def get_ssh_cert_subject() -> str: ...
def set_ssh_cert_subject(value: str) -> None: ...

ssh_cert_subject = property(get_ssh_cert_subject, set_ssh_cert_subject)

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma separated list of distinguished name fields and values. For instance "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are displayed below.

If a field value contains a comma it must be quoted.

ssh_compression_algorithms Property

A comma-separated list containing all allowable compression algorithms.

Syntax

def get_ssh_compression_algorithms() -> str: ...
def set_ssh_compression_algorithms(value: str) -> None: ...

ssh_compression_algorithms = property(get_ssh_compression_algorithms, set_ssh_compression_algorithms)

Default Value

"none,zlib"

Remarks

During the SSH handshake, this list will be used to negotiate the compression algorithm to be used between the client and server. This list is used for both directions: client to server and server to client. When negotiating algorithms, each side sends a list of all algorithms it supports or allows. The algorithm chosen for each direction is the first algorithm to appear in the sender's list that the receiver supports, so it is important to list multiple algorithms in preferential order. If no algorithm can be agreed upon, the class will raise an error and the connection will be aborted.

At least one supported algorithm must appear in this list. The following compression algorithms are supported by the class:

• zlib
• zlib@openssh.com
• none

ssh_encryption_algorithms Property

A comma-separated list containing all allowable encryption algorithms.

Syntax

def get_ssh_encryption_algorithms() -> str: ...
def set_ssh_encryption_algorithms(value: str) -> None: ...

ssh_encryption_algorithms = property(get_ssh_encryption_algorithms, set_ssh_encryption_algorithms)

Default Value

"aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,arcfour256,arcfour128,arcfour,cast128-cbc,aes256-gcm@openssh.com,aes128-gcm@openssh.com,chacha20-poly1305@openssh.com"

Remarks

During the SSH handshake, this list will be used to negotiate the encryption algorithm to be used between the client and server. This list is used for both directions: client to server and server to client. When negotiating algorithms, each side sends a list of all algorithms it supports or allows. The algorithm chosen for each direction is the first algorithm to appear in the sender's list that the receiver supports, so it is important to list multiple algorithms in preferential order. If no algorithm can be agreed upon, the class will raise an error and the connection will be aborted.

At least one supported algorithm must appear in this list. The following encryption algorithms are supported by the class:

change_record_length Method

Changes the length of received data records.

Syntax

def change_record_length(channel_id: int, record_length: int) -> None: ...

Remarks

This method defines the length of data records to be received (in bytes) for the specified ChannelId.

If RecordLength is set to a positive value, the class will accumulate data until RecordLength bytes of data is received and only then fire the on_ssh_channel_data_in event with data of length RecordLength. This allows data to be received as records of known length. This method can be called at any time to change the record length, including within the on_data_in event.

A value of 0 (default) means this functionality is not used.

close_channel Method

Closes a existing SSHChannel .

Syntax

def close_channel(channel_id: int) -> None: ...

Remarks

ChannelId is the identifier for the SSH channel to be closed.

config Method

Sets or retrieves a configuration setting.

Syntax

def config(configuration_string: str) -> str: ...

Remarks

config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

disconnect Method

This method disconnects the specified client.

Syntax

def disconnect(connection_id: int) -> None: ...

Remarks

Calling this method will disconnect the client specified by the ConnectionId parameter.

do_events Method

Processes events from the internal message queue.

Syntax

def do_events() -> None: ...

Remarks

When do_events is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

exchange_keys Method

Causes the class to exchange a new set of session keys on the specified connection.

Syntax

def exchange_keys(connection_id: int) -> None: ...

Remarks

SSH key renegotiation can be initiated by either end of an established SSH connection. exchange_keys allows the server to start such a renegotiation with the client. During this process, on_ssh_status events will fire containing updates regarding the key negotiation process.

The SSH 2.0 specification recommends that key renegotiation be done once for 2 gigabytes (GB) of data processed by the connection, or once every day. This makes it more difficult to break the security of data-intensive or long-lived connections.

get_ssh_param Method

Used to read a field from an SSH packet's payload.

Syntax

def get_ssh_param(payload: bytes, field: str) -> str: ...

Remarks

This method is used to read the value of a particular field from an SSH packet's payload. Payload should contain the full payload of a packet received by an event such as on_ssh_channel_request. Field is the name of a field to be read out of the packet.

The following is a list of the names of well-known channel request field names and their encodings:

The remaining fields that are available in the payload are dependent upon the value of RequestType.

pty-req

Pty-req is a request to open a pseudo terminal on the specified channel. The following fields are available:

x11-req

X11-req is a request to forward x11 sessions over a channel. The following fields are available:

env

Env is a request to set an environment variable to be passed into a shell that may be started later. The following fields are available:

exec

Exec is a request to execute a command on the channel using the authenticated user's shell. The following field is available:

subsystem

Subsystem is a request to start a subsystem on the specified channel. The following field is available:

xon-xoff

Instructs the server to allow or disallow control-S/control-Q style flow control. The following field is available:

signal

Sends a signal to the remote process/service. The following field is available:

If the packet type is not well known, Field should start with the special character "%" and contain a comma-separated list of field types as defined in set_ssh_param. For example, reading out the X11AuthProtocol of an x11-req payload, you can use "%s,f".

Note: the return value is a string encoded the same way as the FieldValue param in set_ssh_param.

get_ssh_param_bytes Method

Used to read a field from an SSH packet's payload.

Syntax

def get_ssh_param_bytes(payload: bytes, field: str) -> bytes: ...

Remarks

This method is the same as calling get_ssh_param, but returns raw bytes instead of strings.

open_channel Method

Opens a new SSHChannel .

Syntax

def open_channel(connection_id: int, channel_type: str) -> str: ...

Remarks

The SSH 2.0 specification allows for multiple channels to be opened over a single TCP/IP connection. The channels property represents the channels that are currently open. A new SSHChannel can be opened with open_channel.

ChannelType represents the type of SSH channel to be opened. The most common type of channel is "session".

If the call to open_channel succeeds, an SSHChannel will be created and added to the channels collection.

reset Method

Reset the class.

Syntax

def reset() -> None: ...

Remarks

This method will reset the class's properties to their default values.

send_bytes Method

Sends binary data to the specified channel.

Syntax

def send_bytes(channel_id: int, data: bytes) -> None: ...

Remarks

This method sends binary data to the channel identified by ChannelId. To send text use the send_text method instead.

send_channel_data Method

Used to send data over an SSH channel.

Syntax

def send_channel_data(channel_id: int, data: bytes) -> None: ...

Remarks

This method can be used to send arbitrary data to the channel with the specified ChannelId.

send_ssh_packet Method

Used to send an encoded SSH packet to the server.

Syntax

def send_ssh_packet(channel_id: int, packet_type: int, payload: bytes) -> None: ...

Remarks

This method can be used to send a previously built SSH payload to the server. ChannelId identifies the channel that will receive the packet.

PacketType identifies what kind of packet is to be sent. Payload should contain the payload of the packet, which can be built by successive calls to set_ssh_param.

When send_ssh_packet is called, the class will finish building the packet, encrypt it for transport, and send it to the server.

send_text Method

Sends text to the specified channel.

Syntax

def send_text(channel_id: int, text: str) -> None: ...

Remarks

This method sends text to the client identified by ChannelId. To send binary data use the send_bytes method instead.

set_ssh_param Method

Used to write a field to the end of a payload.

Syntax

def set_ssh_param(payload: bytes, field_type: str, field_value: str) -> bytes: ...

Remarks

This method is used to build the payload portion of an SSH packet to be sent later by a call to send_ssh_packet. Payload should contain the result of a previous call to set_ssh_param. FieldType is a string defining the type of field to be written to the packet. FieldValue should be the string representation of the field to be written.

The following is a list of supported field types and a description of how FieldValue should be encoded:

Note: integer values may be encoded in hexadecimal by prefixing "0x" to the beginning of the string, otherwise the value is assumed to be base-10.

shutdown Method

This method shuts down the server.

Syntax

def shutdown() -> None: ...

Remarks

This method shuts down the server. Calling this method is equivalent to calling stop_listening and then breaking every client connection by calling disconnect.

start_listening Method

This method starts listening for incoming connections.

Syntax

def start_listening() -> None: ...

Remarks

This method begins listening for incoming connections on the port specified by local_port. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call stop_listening. To stop listening for new connections and to disconnect all existing clients, call shutdown.

stop_listening Method

This method stops listening for new connections.

Syntax

def stop_listening() -> None: ...

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call shutdown instead.

on_connected Event

This event is fired immediately after a connection completes (or fails).

Syntax

class SSHServerConnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

  @property
  def cert_store_type() -> int: ...
  @cert_store_type.setter
  def cert_store_type(value) -> None: ...

  @property
  def cert_store() -> str: ...
  @cert_store.setter
  def cert_store(value) -> None: ...

  @property
  def cert_password() -> str: ...
  @cert_password.setter
  def cert_password(value) -> None: ...

  @property
  def cert_subject() -> str: ...
  @cert_subject.setter
  def cert_subject(value) -> None: ...

# In class SSHServer:
@property
def on_connected() -> Callable[[SSHServerConnectedEventParams], None]: ...
@on_connected.setter
def on_connected(event_hook: Callable[[SSHServerConnectedEventParams], None]) -> None: ...

Remarks

If the connection is made normally, StatusCode is 0, and Description is "OK".

If the connection fails, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

ConnectionId is the connection Id of the client requesting the connection.

CertStoreType is the store type of the alternate certificate to use for this connection. The class supports both public and private keys in a variety of formats. When the cstAuto value is used the class will automatically determine the type. This property can take one of the following values:

CertStore is the store name or location of the alternate certificate to use for this connection.

Designations of certificate stores are platform-dependent.

The following are designations of the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e. PKCS12 certificate store).

CertPassword is the password of the certificate store containing the alternate certificate to use for this connection.

CertSubject is the subject of the alternate certificate to use for this connection.

The special value * matches any subject and will select the first certificate in the store. The certificate subject is a comma separated list of distinguished name fields and values. For instance "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are displayed below.

If a field value contains a comma it must be quoted.

on_connection_request Event

This event is fired when a request for connection comes from a remote host.

Syntax

class SSHServerConnectionRequestEventParams(object):
  @property
  def address() -> str: ...

  @property
  def port() -> int: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class SSHServer:
@property
def on_connection_request() -> Callable[[SSHServerConnectionRequestEventParams], None]: ...
@on_connection_request.setter
def on_connection_request(event_hook: Callable[[SSHServerConnectionRequestEventParams], None]) -> None: ...

Remarks

This event indicates an incoming connection. The connection is accepted by default. Address and Port will contain information about the remote host requesting the inbound connection. If you want to refuse it, you can set the Accept parameter to False.

on_disconnected Event

This event is fired when a connection is closed.

Syntax

class SSHServerDisconnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

# In class SSHServer:
@property
def on_disconnected() -> Callable[[SSHServerDisconnectedEventParams], None]: ...
@on_disconnected.setter
def on_disconnected(event_hook: Callable[[SSHServerDisconnectedEventParams], None]) -> None: ...

Remarks

If the connection is broken normally, StatusCode is 0, and Description is "OK".

If the connection is broken for any other reason, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

on_error Event

Information about errors during data delivery.

Syntax

class SSHServerErrorEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def error_code() -> int: ...

  @property
  def description() -> str: ...

# In class SSHServer:
@property
def on_error() -> Callable[[SSHServerErrorEventParams], None]: ...
@on_error.setter
def on_error(event_hook: Callable[[SSHServerErrorEventParams], None]) -> None: ...

Remarks

The on_error event is fired in case of exceptional conditions during message processing. Normally the class fails with an error.

ConnectionId contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

on_log Event

Fires once for each log message.

Syntax

class SSHServerLogEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def log_level() -> int: ...

  @property
  def message() -> str: ...

  @property
  def log_type() -> str: ...

# In class SSHServer:
@property
def on_log() -> Callable[[SSHServerLogEventParams], None]: ...
@on_log.setter
def on_log(event_hook: Callable[[SSHServerLogEventParams], None]) -> None: ...

Remarks

This event fires once for each log messages generated by the class. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the detail level of the message. Possible values are:

Message is the log message.

LogType is reserved for future use.

ConnectionId specifies the connection to which the log message is applicable.

on_ssh_channel_closed Event

Fired when a channel is closed.

Syntax

class SSHServerSSHChannelClosedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

# In class SSHServer:
@property
def on_ssh_channel_closed() -> Callable[[SSHServerSSHChannelClosedEventParams], None]: ...
@on_ssh_channel_closed.setter
def on_ssh_channel_closed(event_hook: Callable[[SSHServerSSHChannelClosedEventParams], None]) -> None: ...

Remarks

The on_ssh_channel_closed event is fired when a channel is closed on an SSH connection.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_data_in Event

Fired when data is received on an SSH channel.

Syntax

class SSHServerSSHChannelDataInEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

  @property
  def data() -> bytes: ...

# In class SSHServer:
@property
def on_ssh_channel_data_in() -> Callable[[SSHServerSSHChannelDataInEventParams], None]: ...
@on_ssh_channel_data_in.setter
def on_ssh_channel_data_in(event_hook: Callable[[SSHServerSSHChannelDataInEventParams], None]) -> None: ...

Remarks

Whenever a client sends data to an SSH channel, the on_ssh_channel_data_in event will fire. ChannelId will identify the channel receiving data. Data will contain the raw data being received.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_eof Event

Fired when the remote peer signals the end of the data stream for the channel.

Syntax

class SSHServerSSHChannelEOFEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

# In class SSHServer:
@property
def on_ssh_channel_eof() -> Callable[[SSHServerSSHChannelEOFEventParams], None]: ...
@on_ssh_channel_eof.setter
def on_ssh_channel_eof(event_hook: Callable[[SSHServerSSHChannelEOFEventParams], None]) -> None: ...

Remarks

The on_ssh_channel_eof event is fired when the end of the data stream for a channel on an SSH connection is reached.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_opened Event

Fired when a channel is successfully opened.

Syntax

class SSHServerSSHChannelOpenedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

# In class SSHServer:
@property
def on_ssh_channel_opened() -> Callable[[SSHServerSSHChannelOpenedEventParams], None]: ...
@on_ssh_channel_opened.setter
def on_ssh_channel_opened(event_hook: Callable[[SSHServerSSHChannelOpenedEventParams], None]) -> None: ...

Remarks

The on_ssh_channel_opened event is fired when a channel is successfully opened on an SSH connection.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_open_request Event

Fired when a client attempts to open a new channel.

Syntax

class SSHServerSSHChannelOpenRequestEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

  @property
  def service() -> str: ...

  @property
  def parameters() -> bytes: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class SSHServer:
@property
def on_ssh_channel_open_request() -> Callable[[SSHServerSSHChannelOpenRequestEventParams], None]: ...
@on_ssh_channel_open_request.setter
def on_ssh_channel_open_request(event_hook: Callable[[SSHServerSSHChannelOpenRequestEventParams], None]) -> None: ...

Remarks

This event is fired whenever a client attempts to open a new channel for a given connection. ChannelId will contain the id of the channel to be created. Service will identify the type of channel that is being requested (e.g.: "session"). Set Accept to true to accept the channel open request.

ConnectionId identifies the connection. ChannelId identifies the channel.

If the channel open request contains extra information, it will be contained in Parameters; you can extract data from it using get_ssh_param and get_ssh_param_bytes. The most common example of a request with parameters would be a request with Service set to "direct-tcpip" (for SSH tunneling); in that case Parameters will contain the host to connect (string), the port to connect (int), the originator IP address (string) and the originator TCP port (int).

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_ready_to_send Event

Fired when the class is ready to send data.

Syntax

class SSHServerSSHChannelReadyToSendEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

# In class SSHServer:
@property
def on_ssh_channel_ready_to_send() -> Callable[[SSHServerSSHChannelReadyToSendEventParams], None]: ...
@on_ssh_channel_ready_to_send.setter
def on_ssh_channel_ready_to_send(event_hook: Callable[[SSHServerSSHChannelReadyToSendEventParams], None]) -> None: ...

Remarks

This event fires when data can be sent over the SSH Channel specified by ChannelId for the connection specified by ConnectionId.

When a channel is opened this event will fire once the channel is ready and data can be sent.

When timeout is set to 0 (asynchronous) sending data may result in an error if the channel or underlying socket cannot accept more data to send. Monitor on_ssh_channel_ready_to_send or ready_to_send to determine when data can be sent again.

When timeout is set to a positive value the class will block when sending data until the data can be successfully sent and on_ssh_channel_ready_to_send and ready_to_send do not need to be monitored.

on_ssh_channel_request Event

Fired when the SSHHost sends a channel request to the client.

Syntax

class SSHServerSSHChannelRequestEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

  @property
  def request_type() -> str: ...

  @property
  def packet() -> bytes: ...

  @property
  def success() -> bool: ...
  @success.setter
  def success(value) -> None: ...

# In class SSHServer:
@property
def on_ssh_channel_request() -> Callable[[SSHServerSSHChannelRequestEventParams], None]: ...
@on_ssh_channel_request.setter
def on_ssh_channel_request(event_hook: Callable[[SSHServerSSHChannelRequestEventParams], None]) -> None: ...

Remarks

The ssh_host may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the class. However, others may need the attention of the user to be dealt with properly within the scope of the application.

ConnectionId identifies the connection.

ChannelId identifies the channel receiving the request.

Type will contain the type of the request. These types are dependent upon the type of the channel. For example, a "session" channel executing a command on the remote shell may receive an "exit-status" request containing the return code of that command.

RequestData contains the remainder of the original SSH packet. If the request type has specific parameters, they can be parsed out of this data.

Success should be used to instruct the class to respond to the request with either a success or failure notification. If the request is successful, on_ssh_channel_requested will fire with the same information in case the request requires further processing.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_channel_requested Event

Fired if the SSHChannelRequest was successful, any further processing for the channel request should be done here.

Syntax

class SSHServerSSHChannelRequestedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def channel_id() -> int: ...

  @property
  def request_type() -> str: ...

  @property
  def packet() -> bytes: ...

# In class SSHServer:
@property
def on_ssh_channel_requested() -> Callable[[SSHServerSSHChannelRequestedEventParams], None]: ...
@on_ssh_channel_requested.setter
def on_ssh_channel_requested(event_hook: Callable[[SSHServerSSHChannelRequestedEventParams], None]) -> None: ...

Remarks

The ssh_host may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the class. However, others may need the attention of the user to be dealt with properly within the scope of the application.

ConnectionId identifies the connection.

ChannelId identifies the channel receiving the request.

Type will contain the type of the request. These types are dependent upon the type of the channel. For example, a "session" channel executing a command on the remote shell may receive an "exit-status" request containing the return code of that command.

RequestData contains the remainder of the original SSH packet. If the request type has specific parameters, they can be parsed out of this data.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_service_request Event

Fired when a client requests a service to be started.

Syntax

class SSHServerSSHServiceRequestEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def service() -> str: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class SSHServer:
@property
def on_ssh_service_request() -> Callable[[SSHServerSSHServiceRequestEventParams], None]: ...
@on_ssh_service_request.setter
def on_ssh_service_request(event_hook: Callable[[SSHServerSSHServiceRequestEventParams], None]) -> None: ...

Remarks

The on_ssh_service_request event is fired when a client requests that a service be started for a particular connection, identified by ConnectionId. Service will be the name of the service the client wishes to start. If the connection is authenticated and the user has access to the service, set Accept to true to allow the SSHServer to accept the request.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

on_ssh_status Event

Shows the progress of the secure connection.

Syntax

class SSHServerSSHStatusEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def message() -> str: ...

# In class SSHServer:
@property
def on_ssh_status() -> Callable[[SSHServerSSHStatusEventParams], None]: ...
@on_ssh_status.setter
def on_ssh_status(event_hook: Callable[[SSHServerSSHStatusEventParams], None]) -> None: ...

Remarks

The event is fired for informational and logging purposes only. Used to track the progress of the connection.

on_ssh_tunnel_closed Event

This event will fire when a connected client attempts to close a tunnel.

Syntax

class SSHServerSSHTunnelClosedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def address() -> str: ...

  @property
  def port() -> int: ...

# In class SSHServer:
@property
def on_ssh_tunnel_closed() -> Callable[[SSHServerSSHTunnelClosedEventParams], None]: ...
@on_ssh_tunnel_closed.setter
def on_ssh_tunnel_closed(event_hook: Callable[[SSHServerSSHTunnelClosedEventParams], None]) -> None: ...

Remarks

on_ssh_tunnel_requested Event

This event fires when a connected client attempts to establish a forward or reverse tunnel.

Syntax

class SSHServerSSHTunnelRequestedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def direction() -> int: ...

  @property
  def address() -> str: ...

  @property
  def port() -> int: ...
  @port.setter
  def port(value) -> None: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class SSHServer:
@property
def on_ssh_tunnel_requested() -> Callable[[SSHServerSSHTunnelRequestedEventParams], None]: ...
@on_ssh_tunnel_requested.setter
def on_ssh_tunnel_requested(event_hook: Callable[[SSHServerSSHTunnelRequestedEventParams], None]) -> None: ...

Remarks

on_ssh_user_auth_request Event

Fires when a client attempts to authenticate a connection.

Syntax

class SSHServerSSHUserAuthRequestEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def user() -> str: ...

  @property
  def service() -> str: ...

  @property
  def auth_method() -> str: ...

  @property
  def auth_param() -> str: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

  @property
  def partial_success() -> bool: ...
  @partial_success.setter
  def partial_success(value) -> None: ...

  @property
  def available_methods() -> str: ...
  @available_methods.setter
  def available_methods(value) -> None: ...

  @property
  def key_algorithm() -> str: ...

# In class SSHServer:
@property
def on_ssh_user_auth_request() -> Callable[[SSHServerSSHUserAuthRequestEventParams], None]: ...
@on_ssh_user_auth_request.setter
def on_ssh_user_auth_request(event_hook: Callable[[SSHServerSSHUserAuthRequestEventParams], None]) -> None: ...

Remarks

The on_ssh_user_auth_request event fires when an SSH client attempts to authenticate itself on a particular connection. ConnectionId will identify the connection being authenticated. User will be the name of the account requesting authentication, and Service will contain the name of the service the client is wishing to access.

AuthMethod will denote which method the client is attempting to use to authenticate itself. AuthParam will contain the value of the authentication token used by the client. If the token is acceptable, you may set Accept to true to allow the class to authenticate the client. If it is not, set Accept to false.

Connecting clients will initially attempt authentication with an AuthMethod of "none". This is done with the expectation that the request will fail and the server will send a list of supported methods back to the client. In your implementation check the AuthMethod parameter, if it is "none" you should set AvailableMethods and reject the request. The client will select one of the available methods and re-authenticate.

You may set AvailableMethods to a comma-delimited string of authentication methods that are available for the user. This list will be sent back to the client so that it may perform further authentication attempts.

The following is a list of methods implemented by the class:

The PartialSuccess parameter is only used when multi-factor authentication is needed. To implement multi-factor authentication when this event fires first verify the AuthParam for the given AuthMethod. If accepted, set PartialSuccess to true and Accept to false. The client should then send the authentication request for a different form of authentication specified in AvailableMethods. You may continue to set PartialSuccess to true until all authentication requirements are satisfied. Once all requirements are satisfied set Accept to true.

KeyAlgorithm hold the signing algorithm used when the client attempts public key authentication. Possible values are:

• ssh-rsa
• rsa-sha2-256
• rsa-sha2-512
• ssh-dss
• ecdsa-sha2-nistp256
• ecdsa-sha2-nistp384
• ecdsa-sha2-nistp521
• x509v3-sign-rsa
• x509v3-sign-dss

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHServer Config Settings

SSHServer Config Settings

*SSH-1.99-*,*SSH-2.0-*,*SSH-2.99-*

TCPServer Config Settings

Base Config Settings

SSHServer Errors

SSHServer Errors

TCPServer Errors

TCP/IP Errors