MQTTBroker Component

Properties   Methods   Events   Config Settings   Errors  

A lightweight, fully-featured MQTT broker implementation.

Syntax

nsoftware.IPWorksIoT.MQTTBroker

Remarks

The MQTTBroker component provides a lightweight, fully-featured MQTT broker implementation with support for version 3.1.1. The component supports plaintext and TLS-enabled connections over both standard TCP and WebSockets.

Configuring Listeners

The AddBrokerListener method adds a new listener to the Listeners collection. Any listeners must be configured before starting the broker. Multiple protocols can be supported by adding different listeners.

The component supports the following protocols:

0 (mbpTCP) Plaintext TCP
1 (mbpTLS) SSL/TLS over TCP
2 (mbpWS) Plaintext WebSocket
3 (mbpWSS) SSL/TLS over WebSocket

Multiple protocols can be enabled (each on a different port): // Plaintext TCP mqttbroker.AddBrokerListener("127.0.0.1", PLAIN_PORT, (int)MQTTBrokerProtocols.mbpTCP, 0, null, null, null); // TCP with TLS mqttbroker.AddBrokerListener("127.0.0.1", SSL_PORT, (int)MQTTBrokerProtocols.mbpTLS, (int)CertStoreTypes.cstPFXFile, "test1.pfx", "test", "*"); // Plaintext WebSocket mqttbroker.AddBrokerListener("127.0.0.1", WS_PORT, (int)MQTTBrokerProtocols.mbpWS, 0, null, null, null); // WebSocket with TLS mqttbroker.AddBrokerListener("127.0.0.1", WSS_PORT, (int)MQTTBrokerProtocols.mbpWSS, (int)CertStoreTypes.cstPFXFile, "test2.pfx", "test", "*"); Once all listeners have been added, the broker can be started via the StartListening method.

Handling Sessions

When an MQTT client requests a session, the SessionRequest event will fire with session details. The UserName and Password parameters can be checked before setting Accept to True to accept the session request. Accept can be set to False to reject the session request.

broker.OnSessionRequest += (s,e) => { // Check e.UserName and e.Password if needed // Set Accept to true to accept the session request e.Accept = true; };

Handling Subscriptions

When an MQTT client requests to subscribe to a topic, the Subscribe event will fire.

The ClientId is used to identify this client in subsequent actions.

The TopicFilter is the requested topic the client wishes to subscribe to.

The RequestedQoS is the client's preferred QoS level.

ReturnCode is used to confirm the maximum QoS level granted for this subscription or indicate a failure. This can be less than the client's RequestedQoS.

0x00 Success - Maximum QoS 0
0x01 Success - Maximum QoS 1
0x02 Success - Maximum QoS 2
0x80 Failure
When a client requests to unsubscribe from a topic, the Unsubscribe event will fire, specifying which TopicFilter the client is unsubscribing from.

Incoming Messages

The MQTTBroker component will automatically forward received messages to any subscribed clients. Events can be used to record the state of any incoming messages.

The MessageReceiving event fires when a message is initially received and contains message metadata.

The IncomingMessageStatus event fires each time an incoming message's state is updated.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message received previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message was received as a result of subscribing to a topic.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.
  • State: Information about the incoming message's state.
    • 6 - For an incoming QoS 1 message, which has been received from the client, but prior to sending the PUBACK for it. When the PUBACK is sent, the state will change to 10.
    • 7 - For an incoming QoS 2 message, which has been received from a client, but prior to sending the PUBREC for it,
    • 8 - For an incoming QoS 2 message, which has sent the PUBREC, but waiting to receive the PUBREL for it.
    • 9 - For an incoming QoS 2 message, which has received the PUBREL, but prior to sending the PUBCOMP for it. When the PUBCOMP is sent, the state will change to 10.
    • 10 - Message successfully received.
The MessageReceived event fires when the message has completed the acknowledgment process with the client, depending on the QoS level.

Outgoing Messages

The MQTTBroker component will automatically forward received messages to any subscribed clients. Events can be used to record the state of any incoming messages.

The MessageSending event fires when a message is initially sent to a client and contains message metadata.

The OutgoingMessageStatus event fires each time an outgoing message's state is updated.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message is a retained message.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.
  • State: Information about the outgoing message's state.
    • 1 - Outgoing message is waiting to be sent
    • 2 - For an outgoing QoS 1 message, which has been sent to the client and waiting for the PUBACK. When the PUBACK is received, the state will change to 10.
    • 3 - For an outgoing QoS 2 message, which has been sent to the client and waiting for the PUBREC.
    • 4 - For an outgoing QoS 2 message, which has received the PUBREC, prior to sending the PUBREL for it.
    • 5 - For an outgoing QoS 2 message, which has sent the PUBREL. When the PUBCOMP is received, the state will change to 10.
    • 10 - Message successfully sent.

Saving and Loading Sessions

The SaveSession method saves the current state of a client session, including message queues and subscription data, for later retrieval.

SaveSession returns a JSON string representing the client's subscriptions and messages. This can later be loaded via LoadSession to restore the client's state.

The format should be a JSON string with the following parameters: string sessiondata = broker.SaveSession("Client1"); // sessiondata may contain a JSON string with information like this: { "ClientId":"Client1", "Subscriptions":[{ // A collection of the client's subscribed topics "Topic":"topic name", "QoS":2, }], "IncomingMessages": [{ // A collection of incoming messages "MessageId":1, // The incoming message's ID "Topic":"A", // The incoming message's topic "Payload":"54657374", // hexadecimal message payload "QoS":2, // The incoming message's QoS level "DUP":false, // Whether this message is a duplicate "Retain":false, // Whether this is a retained message "PacketId":1, // This message's packet ID "State":3 // See IncomingMessageStatus event for State details }], "OutgoingMessages":[{ // A collection of outgoing messages "MessageId":2, "Topic":"A", "Payload":"54657374", "QoS":2, "DUP":false, "Retain":false, "PacketId":2, "State":3 // See OutgoingMessageStatus event for State details }] } // Later, the LoadSession method can be used to load the session data broker.LoadSession(sessiondata);

Property List


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

ConnectionsA collection of currently connected clients.
DefaultIdleTimeoutThis property includes the default idle timeout for inactive clients.
ListenersDefines the set of network endpoints where the MQTT Broker listens for client connections.
ListeningThis property indicates whether the component is listening for incoming connections on LocalPort.
MessagesProvides a collection of retained messages available to newly subscribed clients.
SessionsContains session information for clients.
SSLProviderThe Secure Sockets Layer/Transport Layer Security (SSL/TLS) implementation to use.

Method List


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

AddBrokerListenerCreates a new listener for the broker service.
ConfigSets or retrieves a configuration setting.
DisconnectThis method disconnects the specified client.
DoEventsThis method processes events from the internal message queue.
InterruptThis method interrupts a synchronous send to the remote host.
LoadSessionRestores session data for a specified client, enabling resumption of pending operations or message delivery.
ResetThis method will reset the component.
SaveSessionSaves the current state of a client session, including message queues and subscription data, for later retrieval.
ShutdownThis method shuts down the server.
StartListeningThis method starts listening for incoming connections.
StopListeningThis method stops listening for new connections.

Event List


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

ConnectedThis event is fired immediately after a connection completes (or fails).
ConnectionRequestThis event is fired when a request for connection comes from a remote host.
DisconnectedThis event is fired when a connection is closed.
ErrorThis event fires information about errors during data delivery.
IncomingMessageStatusFires when an incoming message's state is updated.
LogFires once for each log message.
MessageReceivedFires when a new message is received from a client.
MessageReceivingFires when a message is initially received from a client.
MessageSendingFires when a message is initially sent to a client.
MessageSentFires after a message is successfully delivered to a client, confirming transmission.
OutgoingMessageStatusFired to provide the current delivery status of an outgoing message. Includes success or failure metadata.
SessionRemovedFired when a client session is removed, indicating all resources associated with the session are cleaned up.
SessionRequestFires when a new session is requested.
SSLClientAuthenticationThis event is fired when the client presents its credentials to the server.
SSLStatusThis event is fired to show the progress of the secure connection.
SubscribeFires when a client requests to subscribe to a topic.
UnsubscribeFires when a client unsubscribes from a topic, removing its subscription data.

Config Settings


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

CloseStreamAfterTransferIf true, the component will close the upload or download stream after the transfer.
ConnectionTimeoutSets a separate timeout value for establishing a connection.
FirewallAutoDetectTells the component whether or not to automatically detect and use firewall system settings, if available.
FirewallHostName or IP address of firewall (optional).
FirewallListenerIf true, the component binds to a SOCKS firewall as a server (TCPClient only).
FirewallPasswordPassword to be used if authentication is to be used when connecting through the firewall.
FirewallPortThe TCP port for the FirewallHost;.
FirewallTypeDetermines the type of firewall to connect through.
FirewallUserA user name if authentication is to be used connecting through a firewall.
KeepAliveIntervalThe retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.
KeepAliveTimeThe inactivity time in milliseconds before a TCP keep-alive packet is sent.
LingerWhen set to True, connections are terminated gracefully.
LingerTimeTime in seconds to have the connection linger.
LocalHostThe name of the local host through which connections are initiated or accepted.
LocalPortThe port in the local host where the component binds.
MaxLineLengthThe maximum amount of data to accumulate when no EOL is found.
MaxTransferRateThe transfer rate limit in bytes per second.
ProxyExceptionsListA semicolon separated list of hosts and IPs to bypass when using a proxy.
TCPKeepAliveDetermines whether or not the keep alive socket option is enabled.
TcpNoDelayWhether or not to delay when sending packets.
UseIPv6Whether to use IPv6.
UseNTLMv2Whether to use NTLM V2.
CACertFilePathsThe paths to CA certificate files when using Mono on Unix/Linux.
LogSSLPacketsControls whether SSL packets are logged when using the internal security API.
ReuseSSLSessionDetermines if the SSL session is reused.
SSLCACertsA newline separated list of CA certificates to be included when performing an SSL handshake.
SSLCheckCRLWhether to check the Certificate Revocation List for the server certificate.
SSLCheckOCSPWhether to use OCSP to check the status of the server certificate.
SSLCipherStrengthThe minimum cipher strength used for bulk encryption.
SSLClientCACertsA newline separated list of CA certificates to use during SSL client certificate validation.
SSLEnabledCipherSuitesThe cipher suite to be used in an SSL negotiation.
SSLEnabledProtocolsUsed to enable/disable the supported security protocols.
SSLEnableRenegotiationWhether the renegotiation_info SSL extension is supported.
SSLIncludeCertChainWhether the entire certificate chain is included in the SSLServerAuthentication event.
SSLKeyLogFileThe location of a file where per-session secrets are written for debugging purposes.
SSLNegotiatedCipherReturns the negotiated cipher suite.
SSLNegotiatedCipherStrengthReturns the negotiated cipher suite strength.
SSLNegotiatedCipherSuiteReturns the negotiated cipher suite.
SSLNegotiatedKeyExchangeReturns the negotiated key exchange algorithm.
SSLNegotiatedKeyExchangeStrengthReturns the negotiated key exchange algorithm strength.
SSLNegotiatedVersionReturns the negotiated protocol version.
SSLSecurityFlagsFlags that control certificate verification.
SSLServerCACertsA newline separated list of CA certificates to use during SSL server certificate validation.
TLS12SignatureAlgorithmsDefines the allowed TLS 1.2 signature algorithms when SSLProvider is set to Internal.
TLS12SupportedGroupsThe supported groups for ECC.
TLS13KeyShareGroupsThe groups for which to pregenerate key shares.
TLS13SignatureAlgorithmsThe allowed certificate signature algorithms.
TLS13SupportedGroupsThe supported groups for (EC)DHE key exchange.
AbsoluteTimeoutDetermines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallDataUsed to send extra data to the firewall.
InBufferSizeThe size in bytes of the incoming queue of the socket.
OutBufferSizeThe size in bytes of the outgoing queue of the socket.
BuildInfoInformation about the product's build.
GUIAvailableWhether or not a message loop is available for processing events.
LicenseInfoInformation about the current license.
MaskSensitiveDataWhether sensitive data is masked in log messages.
UseFIPSCompliantAPITells the component whether or not to use FIPS certified APIs.
UseInternalSecurityAPIWhether or not to use the system security libraries or an internal implementation.

Connections Property (MQTTBroker Component)

A collection of currently connected clients.

Syntax

public MQTTBrokerConnectionMap Connections { get; }
Public ReadOnly Property Connections As MQTTBrokerConnectionMap

Remarks

This property contains a collection of currently connected clients. All of the connections may be managed using this property. Each connection is described by the different fields of the Connection type.

This collection is a hash-table type of collection, in which the Connection Id string is used as the key to the desired connection. You may acquire the key for a given connection through the Connected event.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerConnection type for a complete list of fields.

DefaultIdleTimeout Property (MQTTBroker Component)

This property includes the default idle timeout for inactive clients.

Syntax

public int DefaultIdleTimeout { get; set; }
Public Property DefaultIdleTimeout As Integer

Default Value

0

Remarks

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

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

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

Note: DoEvents must be called for the component to check existing connections.

Listeners Property (MQTTBroker Component)

Defines the set of network endpoints where the MQTT Broker listens for client connections.

Syntax

public MQTTBrokerListenerList Listeners { get; }
Public ReadOnly Property Listeners As MQTTBrokerListenerList

Remarks

Each listener is represented by an endpoint structure, including IP address and port. This allows fine-grained control over accessibility and security, enabling the broker to serve clients on different networks or with different protocols.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerListener type for a complete list of fields.

Listening Property (MQTTBroker Component)

This property indicates whether the component is listening for incoming connections on LocalPort.

Syntax

public bool Listening { get; }
Public ReadOnly Property Listening As Boolean

Default Value

False

Remarks

This property indicates whether the component is listening for connections on the port specified by the LocalPort property. Use the StartListening and StopListening methods to control whether the component is listening.

This property is read-only and not available at design time.

Messages Property (MQTTBroker Component)

Provides a collection of retained messages available to newly subscribed clients.

Syntax

public MQTTBrokerMessageList Messages { get; }
Public ReadOnly Property Messages As MQTTBrokerMessageList

Remarks

Retained messages are stored and delivered to clients subscribing to their respective topics. This property allows inspection and management of retained messages, including adding, modifying, or removing messages for specific topics.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerMessage type for a complete list of fields.

Sessions Property (MQTTBroker Component)

Contains session information for clients.

Syntax

public MQTTBrokerSessionList Sessions { get; }
Public ReadOnly Property Sessions As MQTTBrokerSessionList

Remarks

Session data includes stored messages, subscription topics, and QoS levels. This ensures that messages are delivered even if a client reconnects after a disconnection.

This property is read-only and not available at design time.

Please refer to the MQTTBrokerSession type for a complete list of fields.

SSLProvider Property (MQTTBroker Component)

The Secure Sockets Layer/Transport Layer Security (SSL/TLS) implementation to use.

Syntax

public MQTTBrokerSSLProviders SSLProvider { get; set; }

enum MQTTBrokerSSLProviders { sslpAutomatic, sslpPlatform, sslpInternal }
Public Property SSLProvider As MqttbrokerSSLProviders

Enum MQTTBrokerSSLProviders sslpAutomatic sslpPlatform sslpInternal End Enum

Default Value

0

Remarks

This property specifies the SSL/TLS implementation to use. In most cases the default value of 0 (Automatic) is recommended and should not be changed. When set to 0 (Automatic), the component will select whether to use the platform implementation or the internal implementation depending on the operating system as well as the TLS version being used.

Possible values are as follows:

0 (sslpAutomatic - default)Automatically selects the appropriate implementation.
1 (sslpPlatform) Uses the platform/system implementation.
2 (sslpInternal) Uses the internal implementation.
Additional Notes

In most cases using the default value (Automatic) is recommended. The component will select a provider depending on the current platform.

When Automatic is selected, on Windows, the component will use the platform implementation. On Linux/macOS, the component will use the internal implementation. When TLS 1.3 is enabled via SSLEnabledProtocols, the internal implementation is used on all platforms.

The .NET Standard library will always use the internal implementation on all platforms.

AddBrokerListener Method (MQTTBroker Component)

Creates a new listener for the broker service.

Syntax

public void AddBrokerListener(string localHost, int localPort, int protocol, int SSLCertStoreType, byte[] SSLCertStore, string SSLCertStorePassword, string SSLCertSubject);

Async Version
public async Task AddBrokerListener(string localHost, int localPort, int protocol, int SSLCertStoreType, byte[] SSLCertStore, string SSLCertStorePassword, string SSLCertSubject);
public async Task AddBrokerListener(string localHost, int localPort, int protocol, int SSLCertStoreType, byte[] SSLCertStore, string SSLCertStorePassword, string SSLCertSubject, CancellationToken cancellationToken);
Public Sub AddBrokerListener(ByVal LocalHost As String, ByVal LocalPort As Integer, ByVal Protocol As Integer, ByVal SSLCertStoreType As Integer, ByVal SSLCertStore As String, ByVal SSLCertStorePassword As String, ByVal SSLCertSubject As String)

Async Version
Public Sub AddBrokerListener(ByVal LocalHost As String, ByVal LocalPort As Integer, ByVal Protocol As Integer, ByVal SSLCertStoreType As Integer, ByVal SSLCertStore As String, ByVal SSLCertStorePassword As String, ByVal SSLCertSubject As String) As Task
Public Sub AddBrokerListener(ByVal LocalHost As String, ByVal LocalPort As Integer, ByVal Protocol As Integer, ByVal SSLCertStoreType As Integer, ByVal SSLCertStore As String, ByVal SSLCertStorePassword As String, ByVal SSLCertSubject As String, cancellationToken As CancellationToken) As Task

Remarks

AddBrokerListener adds a new listener to the Listeners collection. Any listeners must be configured before starting the broker. Multiple protocols can be supported by adding different listeners.

The component supports the following protocols:

0 (mbpTCP) Plaintext TCP
1 (mbpTLS) SSL/TLS over TCP
2 (mbpWS) Plaintext WebSocket
3 (mbpWSS) SSL/TLS over WebSocket

Certificate details can be provided via the following parameters:

SSLCertStoreType The type of certificate store for this certificate.
SSLCertStore The name of the certificate store for the client certificate. This can be null for plaintext.
SSLCertStorePassword If the type of certificate store requires a password, this field is used to specify the password needed to open the certificate store.
SSLCertSubject The subject of the certificate used for client authentication.
Multiple protocols can be enabled (each on a different port): // Plaintext TCP mqttbroker.AddBrokerListener("127.0.0.1", PLAIN_PORT, (int)MQTTBrokerProtocols.mbpTCP, 0, null, null, null); // TCP with TLS mqttbroker.AddBrokerListener("127.0.0.1", SSL_PORT, (int)MQTTBrokerProtocols.mbpTLS, (int)CertStoreTypes.cstPFXFile, "test1.pfx", "test", "*"); // Plaintext WebSocket mqttbroker.AddBrokerListener("127.0.0.1", WS_PORT, (int)MQTTBrokerProtocols.mbpWS, 0, null, null, null); // WebSocket with TLS mqttbroker.AddBrokerListener("127.0.0.1", WSS_PORT, (int)MQTTBrokerProtocols.mbpWSS, (int)CertStoreTypes.cstPFXFile, "test2.pfx", "test", "*");

Config Method (MQTTBroker Component)

Sets or retrieves a configuration setting.

Syntax

public string Config(string configurationString);

Async Version
public async Task<string> Config(string configurationString);
public async Task<string> Config(string configurationString, CancellationToken cancellationToken);
Public Function Config(ByVal ConfigurationString As String) As String

Async Version
Public Function Config(ByVal ConfigurationString As String) As Task(Of String)
Public Function Config(ByVal ConfigurationString As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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 (MQTTBroker Component)

This method disconnects the specified client.

Syntax

public void Disconnect(string connectionId);

Async Version
public async Task Disconnect(string connectionId);
public async Task Disconnect(string connectionId, CancellationToken cancellationToken);
Public Sub Disconnect(ByVal ConnectionId As String)

Async Version
Public Sub Disconnect(ByVal ConnectionId As String) As Task
Public Sub Disconnect(ByVal ConnectionId As String, cancellationToken As CancellationToken) As Task

Remarks

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

DoEvents Method (MQTTBroker Component)

This method processes events from the internal message queue.

Syntax

public void DoEvents();

Async Version
public async Task DoEvents();
public async Task DoEvents(CancellationToken cancellationToken);
Public Sub DoEvents()

Async Version
Public Sub DoEvents() As Task
Public Sub DoEvents(cancellationToken As CancellationToken) As Task

Remarks

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

Interrupt Method (MQTTBroker Component)

This method interrupts a synchronous send to the remote host.

Syntax

public void Interrupt(string connectionId);

Async Version
public async Task Interrupt(string connectionId);
public async Task Interrupt(string connectionId, CancellationToken cancellationToken);
Public Sub Interrupt(ByVal ConnectionId As String)

Async Version
Public Sub Interrupt(ByVal ConnectionId As String) As Task
Public Sub Interrupt(ByVal ConnectionId As String, cancellationToken As CancellationToken) As Task

Remarks

This property is called using the Connection Id if you wish to interrupt a connection and stop a file from uploading without disconnecting the client connected to the component. If you use SendFile to upload a file, the component will run synchronously on that Connection Id until it is completed.

LoadSession Method (MQTTBroker Component)

Restores session data for a specified client, enabling resumption of pending operations or message delivery.

Syntax

public void LoadSession(string sessionInfo);

Async Version
public async Task LoadSession(string sessionInfo);
public async Task LoadSession(string sessionInfo, CancellationToken cancellationToken);
Public Sub LoadSession(ByVal sessionInfo As String)

Async Version
Public Sub LoadSession(ByVal sessionInfo As String) As Task
Public Sub LoadSession(ByVal sessionInfo As String, cancellationToken As CancellationToken) As Task

Remarks

The LoadSession method is used to load prior client session information if required. This can be used after shutting down a broker to preserve session data and ensure messages can be redelivered once the broker is restarted.

The SaveSession method can be used to save session data, and the resulting string can be provided to the LoadSession method.

The format should be a JSON string with the following parameters: { "ClientId":"Client1", "Subscriptions":[{ // A collection of the client's subscribed topics "Topic":"topic name", "QoS":2, }], "IncomingMessages": [{ // A collection of incoming messages "MessageId":1, // The incoming message's ID "Topic":"A", // The incoming message's topic "Payload":"54657374", // hexadecimal message payload "QoS":2, // The incoming message's QoS level "DUP":false, // Whether this message is a duplicate "Retain":false, // Whether this is a retained message "PacketId":1, // This message's packet ID "State":3 // See IncomingMessageStatus event for State details }], "OutgoingMessages":[{ // A collection of outgoing messages "MessageId":2, "Topic":"A", "Payload":"54657374", "QoS":2, "DUP":false, "Retain":false, "PacketId":2, "State":3 // See OutgoingMessageStatus event for State details }] } Session data can be saved with SaveSession, then later loaded with LoadSession string sessiondata = broker.SaveSession("Client1"); // sessiondata contains session information for Client1 ... broker.LoadSession(sessiondata);

Reset Method (MQTTBroker Component)

This method will reset the component.

Syntax

public void Reset();

Async Version
public async Task Reset();
public async Task Reset(CancellationToken cancellationToken);
Public Sub Reset()

Async Version
Public Sub Reset() As Task
Public Sub Reset(cancellationToken As CancellationToken) As Task

Remarks

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

SaveSession Method (MQTTBroker Component)

Saves the current state of a client session, including message queues and subscription data, for later retrieval.

Syntax

public string SaveSession(string clientId);

Async Version
public async Task<string> SaveSession(string clientId);
public async Task<string> SaveSession(string clientId, CancellationToken cancellationToken);
Public Function SaveSession(ByVal clientId As String) As String

Async Version
Public Function SaveSession(ByVal clientId As String) As Task(Of String)
Public Function SaveSession(ByVal clientId As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

Returns a JSON string representing the client's subscriptions and messages. This can later be loaded via LoadSession to restore the client's state.

The format should be a JSON string with the following parameters: string sessiondata = broker.SaveSession("Client1"); // sessiondata may contain a JSON string with information like this: { "ClientId":"Client1", "Subscriptions":[{ // A collection of the client's subscribed topics "Topic":"topic name", "QoS":2, }], "IncomingMessages": [{ // A collection of incoming messages "MessageId":1, // The incoming message's ID "Topic":"A", // The incoming message's topic "Payload":"54657374", // hexadecimal message payload "QoS":2, // The incoming message's QoS level "DUP":false, // Whether this message is a duplicate "Retain":false, // Whether this is a retained message "PacketId":1, // This message's packet ID "State":3 // See IncomingMessageStatus event for State details }], "OutgoingMessages":[{ // A collection of outgoing messages "MessageId":2, "Topic":"A", "Payload":"54657374", "QoS":2, "DUP":false, "Retain":false, "PacketId":2, "State":3 // See OutgoingMessageStatus event for State details }] }

Shutdown Method (MQTTBroker Component)

This method shuts down the server.

Syntax

public void Shutdown();

Async Version
public async Task Shutdown();
public async Task Shutdown(CancellationToken cancellationToken);
Public Sub Shutdown()

Async Version
Public Sub Shutdown() As Task
Public Sub Shutdown(cancellationToken As CancellationToken) As Task

Remarks

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

StartListening Method (MQTTBroker Component)

This method starts listening for incoming connections.

Syntax

public void StartListening();

Async Version
public async Task StartListening();
public async Task StartListening(CancellationToken cancellationToken);
Public Sub StartListening()

Async Version
Public Sub StartListening() As Task
Public Sub StartListening(cancellationToken As CancellationToken) As Task

Remarks

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

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StopListening Method (MQTTBroker Component)

This method stops listening for new connections.

Syntax

public void StopListening();

Async Version
public async Task StopListening();
public async Task StopListening(CancellationToken cancellationToken);
Public Sub StopListening()

Async Version
Public Sub StopListening() As Task
Public Sub StopListening(cancellationToken As CancellationToken) As Task

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.

Connected Event (MQTTBroker Component)

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

Syntax

public event OnConnectedHandler OnConnected;

public delegate void OnConnectedHandler(object sender, MQTTBrokerConnectedEventArgs e);

public class MQTTBrokerConnectedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}
Public Event OnConnected As OnConnectedHandler

Public Delegate Sub OnConnectedHandler(sender As Object, e As MQTTBrokerConnectedEventArgs)

Public Class MQTTBrokerConnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

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.

ConnectionRequest Event (MQTTBroker Component)

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

Syntax

public event OnConnectionRequestHandler OnConnectionRequest;

public delegate void OnConnectionRequestHandler(object sender, MQTTBrokerConnectionRequestEventArgs e);

public class MQTTBrokerConnectionRequestEventArgs : EventArgs {
  public string Address { get; }
  public int Port { get; }
  public bool Accept { get; set; }
}
Public Event OnConnectionRequest As OnConnectionRequestHandler

Public Delegate Sub OnConnectionRequestHandler(sender As Object, e As MQTTBrokerConnectionRequestEventArgs)

Public Class MQTTBrokerConnectionRequestEventArgs Inherits EventArgs
  Public ReadOnly Property Address As String
  Public ReadOnly Property Port As Integer
  Public Property Accept As Boolean
End Class

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.

Disconnected Event (MQTTBroker Component)

This event is fired when a connection is closed.

Syntax

public event OnDisconnectedHandler OnDisconnected;

public delegate void OnDisconnectedHandler(object sender, MQTTBrokerDisconnectedEventArgs e);

public class MQTTBrokerDisconnectedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}
Public Event OnDisconnected As OnDisconnectedHandler

Public Delegate Sub OnDisconnectedHandler(sender As Object, e As MQTTBrokerDisconnectedEventArgs)

Public Class MQTTBrokerDisconnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

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.

Error Event (MQTTBroker Component)

This event fires information about errors during data delivery.

Syntax

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, MQTTBrokerErrorEventArgs e);

public class MQTTBrokerErrorEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int ErrorCode { get; }
  public string Description { get; }
}
Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As MQTTBrokerErrorEventArgs)

Public Class MQTTBrokerErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally, the component throws an exception.

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.

ConnectionId indicates the connection for which the error is applicable.

IncomingMessageStatus Event (MQTTBroker Component)

Fires when an incoming message's state is updated.

Syntax

public event OnIncomingMessageStatusHandler OnIncomingMessageStatus;

public delegate void OnIncomingMessageStatusHandler(object sender, MQTTBrokerIncomingMessageStatusEventArgs e);

public class MQTTBrokerIncomingMessageStatusEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
  public bool DUP { get; }
  public int QoS { get; }
  public bool Retain { get; }
  public int PacketId { get; }
  public int State { get; }
}
Public Event OnIncomingMessageStatus As OnIncomingMessageStatusHandler

Public Delegate Sub OnIncomingMessageStatusHandler(sender As Object, e As MQTTBrokerIncomingMessageStatusEventArgs)

Public Class MQTTBrokerIncomingMessageStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
  Public ReadOnly Property DUP As Boolean
  Public ReadOnly Property QoS As Integer
  Public ReadOnly Property Retain As Boolean
  Public ReadOnly Property PacketId As Integer
  Public ReadOnly Property State As Integer
End Class

Remarks

The IncomingMessageStatus event fires each time an incoming message's state is updated.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message received previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message was received as a result of subscribing to a topic.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.
  • State: Information about the incoming message's state.
    • 6 - For an incoming QoS 1 message, which has been received from the client, but prior to sending the PUBACK for it. When the PUBACK is sent, the state will change to 10.
    • 7 - For an incoming QoS 2 message, which has been received from a client, but prior to sending the PUBREC for it,
    • 8 - For an incoming QoS 2 message, which has sent the PUBREC, but waiting to receive the PUBREL for it.
    • 9 - For an incoming QoS 2 message, which has received the PUBREL, but prior to sending the PUBCOMP for it. When the PUBCOMP is sent, the state will change to 10.
    • 10 - Message successfully received.

Log Event (MQTTBroker Component)

Fires once for each log message.

Syntax

public event OnLogHandler OnLog;

public delegate void OnLogHandler(object sender, MQTTBrokerLogEventArgs e);

public class MQTTBrokerLogEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int LogLevel { get; }
  public string Message { get; }
  public string LogType { get; }
}
Public Event OnLog As OnLogHandler

Public Delegate Sub OnLogHandler(sender As Object, e As MQTTBrokerLogEventArgs)

Public Class MQTTBrokerLogEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property LogLevel As Integer
  Public ReadOnly Property Message As String
  Public ReadOnly Property LogType As String
End Class

Remarks

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

LogLevel indicates the level of the Message. Possible values are:

0 (None) No events are logged.
1 (Info - default) Informational events are logged.
2 (Verbose) Detailed data is logged.
3 (Debug) Debug data is logged.

LogType identifies the type of log entry. Possible values are:

  • Info: General information about the component.
  • Session: Session status messages.
  • Frame: Frame status messages.

MessageReceived Event (MQTTBroker Component)

Fires when a new message is received from a client.

Syntax

public event OnMessageReceivedHandler OnMessageReceived;

public delegate void OnMessageReceivedHandler(object sender, MQTTBrokerMessageReceivedEventArgs e);

public class MQTTBrokerMessageReceivedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
}
Public Event OnMessageReceived As OnMessageReceivedHandler

Public Delegate Sub OnMessageReceivedHandler(sender As Object, e As MQTTBrokerMessageReceivedEventArgs)

Public Class MQTTBrokerMessageReceivedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
End Class

Remarks

This event fires each time a message is received from a client.

MessageReceiving Event (MQTTBroker Component)

Fires when a message is initially received from a client.

Syntax

public event OnMessageReceivingHandler OnMessageReceiving;

public delegate void OnMessageReceivingHandler(object sender, MQTTBrokerMessageReceivingEventArgs e);

public class MQTTBrokerMessageReceivingEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
  public bool DUP { get; }
  public int QoS { get; }
  public bool Retain { get; }
  public int PacketId { get; }
}
Public Event OnMessageReceiving As OnMessageReceivingHandler

Public Delegate Sub OnMessageReceivingHandler(sender As Object, e As MQTTBrokerMessageReceivingEventArgs)

Public Class MQTTBrokerMessageReceivingEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
  Public ReadOnly Property DUP As Boolean
  Public ReadOnly Property QoS As Integer
  Public ReadOnly Property Retain As Boolean
  Public ReadOnly Property PacketId As Integer
End Class

Remarks

The MessageReceiving event fires once for each incoming message immediately after it is received from a client.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message was received as a result of subscribing to a topic.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.

MessageSending Event (MQTTBroker Component)

Fires when a message is initially sent to a client.

Syntax

public event OnMessageSendingHandler OnMessageSending;

public delegate void OnMessageSendingHandler(object sender, MQTTBrokerMessageSendingEventArgs e);

public class MQTTBrokerMessageSendingEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
  public bool DUP { get; }
  public int QoS { get; }
  public bool Retain { get; }
  public int PacketId { get; }
}
Public Event OnMessageSending As OnMessageSendingHandler

Public Delegate Sub OnMessageSendingHandler(sender As Object, e As MQTTBrokerMessageSendingEventArgs)

Public Class MQTTBrokerMessageSendingEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
  Public ReadOnly Property DUP As Boolean
  Public ReadOnly Property QoS As Integer
  Public ReadOnly Property Retain As Boolean
  Public ReadOnly Property PacketId As Integer
End Class

Remarks

The MessageSending fires once for each outgoing message immediately after it is sent to a client.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message was received as a result of subscribing to a topic.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.

MessageSent Event (MQTTBroker Component)

Fires after a message is successfully delivered to a client, confirming transmission.

Syntax

public event OnMessageSentHandler OnMessageSent;

public delegate void OnMessageSentHandler(object sender, MQTTBrokerMessageSentEventArgs e);

public class MQTTBrokerMessageSentEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
}
Public Event OnMessageSent As OnMessageSentHandler

Public Delegate Sub OnMessageSentHandler(sender As Object, e As MQTTBrokerMessageSentEventArgs)

Public Class MQTTBrokerMessageSentEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
End Class

Remarks

This event fires each time a message is delivered to a client.

OutgoingMessageStatus Event (MQTTBroker Component)

Fired to provide the current delivery status of an outgoing message. Includes success or failure metadata.

Syntax

public event OnOutgoingMessageStatusHandler OnOutgoingMessageStatus;

public delegate void OnOutgoingMessageStatusHandler(object sender, MQTTBrokerOutgoingMessageStatusEventArgs e);

public class MQTTBrokerOutgoingMessageStatusEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public long MessageId { get; }
  public bool DUP { get; }
  public int QoS { get; }
  public bool Retain { get; }
  public int PacketId { get; }
  public int State { get; }
}
Public Event OnOutgoingMessageStatus As OnOutgoingMessageStatusHandler

Public Delegate Sub OnOutgoingMessageStatusHandler(sender As Object, e As MQTTBrokerOutgoingMessageStatusEventArgs)

Public Class MQTTBrokerOutgoingMessageStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property MessageId As Long
  Public ReadOnly Property DUP As Boolean
  Public ReadOnly Property QoS As Integer
  Public ReadOnly Property Retain As Boolean
  Public ReadOnly Property PacketId As Integer
  Public ReadOnly Property State As Integer
End Class

Remarks

The OutgoingMessageStatus event fires each time an outgoing message's state is updated.

  • MessageId: A unique identifier for this message.
  • DUP: Whether or not the server has indicated that this message is a duplicate of another message sent previously.
  • QoS: The message's QoS level.
  • Retain: Whether or not this message is a retained message.
  • PacketId: The message packet Id. This will always be -1 if QoS is 0.
  • State: Information about the outgoing message's state.
    • 1 - Outgoing message is waiting to be sent
    • 2 - For an outgoing QoS 1 message, which has been sent to the client and waiting for the PUBACK. When the PUBACK is received, the state will change to 10.
    • 3 - For an outgoing QoS 2 message, which has been sent to the client and waiting for the PUBREC.
    • 4 - For an outgoing QoS 2 message, which has received the PUBREC, prior to sending the PUBREL for it.
    • 5 - For an outgoing QoS 2 message, which has sent the PUBREL. When the PUBCOMP is received, the state will change to 10.
    • 10 - Message successfully sent.

SessionRemoved Event (MQTTBroker Component)

Fired when a client session is removed, indicating all resources associated with the session are cleaned up.

Syntax

public event OnSessionRemovedHandler OnSessionRemoved;

public delegate void OnSessionRemovedHandler(object sender, MQTTBrokerSessionRemovedEventArgs e);

public class MQTTBrokerSessionRemovedEventArgs : EventArgs {
  public string ClientId { get; }
}
Public Event OnSessionRemoved As OnSessionRemovedHandler

Public Delegate Sub OnSessionRemovedHandler(sender As Object, e As MQTTBrokerSessionRemovedEventArgs)

Public Class MQTTBrokerSessionRemovedEventArgs Inherits EventArgs
  Public ReadOnly Property ClientId As String
End Class

Remarks

The client with the associated ClientId will also be removed from the Sessions collection when this event returns.

SessionRequest Event (MQTTBroker Component)

Fires when a new session is requested.

Syntax

public event OnSessionRequestHandler OnSessionRequest;

public delegate void OnSessionRequestHandler(object sender, MQTTBrokerSessionRequestEventArgs e);

public class MQTTBrokerSessionRequestEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public string UserName { get; }
  public string Password { get; }
  public bool IsNew { get; }
  public bool Accept { get; set; }
}
Public Event OnSessionRequest As OnSessionRequestHandler

Public Delegate Sub OnSessionRequestHandler(sender As Object, e As MQTTBrokerSessionRequestEventArgs)

Public Class MQTTBrokerSessionRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property UserName As String
  Public ReadOnly Property Password As String
  Public ReadOnly Property IsNew As Boolean
  Public Property Accept As Boolean
End Class

Remarks

UserName and Password contain authentication credentials which can be verified in this event.

IsNew denotes whether this is a clean session from the client.

Accept can be set to false to reject the client. Set Accept to true to accept this client.

Example: broker.OnSessionRequest += (s,e) => { // Check e.UserName and e.Password if needed // Set Accept to true to accept the session request e.Accept = true; };

SSLClientAuthentication Event (MQTTBroker Component)

This event is fired when the client presents its credentials to the server.

Syntax

public event OnSSLClientAuthenticationHandler OnSSLClientAuthentication;

public delegate void OnSSLClientAuthenticationHandler(object sender, MQTTBrokerSSLClientAuthenticationEventArgs e);

public class MQTTBrokerSSLClientAuthenticationEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string CertEncoded { get; }
public byte[] CertEncodedB { get; } public string CertSubject { get; } public string CertIssuer { get; } public string Status { get; } public bool Accept { get; set; } }
Public Event OnSSLClientAuthentication As OnSSLClientAuthenticationHandler

Public Delegate Sub OnSSLClientAuthenticationHandler(sender As Object, e As MQTTBrokerSSLClientAuthenticationEventArgs)

Public Class MQTTBrokerSSLClientAuthenticationEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property CertEncoded As String
Public ReadOnly Property CertEncodedB As Byte() Public ReadOnly Property CertSubject As String Public ReadOnly Property CertIssuer As String Public ReadOnly Property Status As String Public Property Accept As Boolean End Class

Remarks

This event enables the server to decide whether or not to continue. The Accept parameter is a recommendation on whether to continue or to close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK").

SSLStatus Event (MQTTBroker Component)

This event is fired to show the progress of the secure connection.

Syntax

public event OnSSLStatusHandler OnSSLStatus;

public delegate void OnSSLStatusHandler(object sender, MQTTBrokerSSLStatusEventArgs e);

public class MQTTBrokerSSLStatusEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string Message { get; }
}
Public Event OnSSLStatus As OnSSLStatusHandler

Public Delegate Sub OnSSLStatusHandler(sender As Object, e As MQTTBrokerSSLStatusEventArgs)

Public Class MQTTBrokerSSLStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property Message As String
End Class

Remarks

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

Subscribe Event (MQTTBroker Component)

Fires when a client requests to subscribe to a topic.

Syntax

public event OnSubscribeHandler OnSubscribe;

public delegate void OnSubscribeHandler(object sender, MQTTBrokerSubscribeEventArgs e);

public class MQTTBrokerSubscribeEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public string TopicFilter { get; }
  public int RequestedQoS { get; }
  public int ReturnCode { get; set; }
}
Public Event OnSubscribe As OnSubscribeHandler

Public Delegate Sub OnSubscribeHandler(sender As Object, e As MQTTBrokerSubscribeEventArgs)

Public Class MQTTBrokerSubscribeEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property TopicFilter As String
  Public ReadOnly Property RequestedQoS As Integer
  Public Property ReturnCode As Integer
End Class

Remarks

The ClientId is used to identify this client in subsequent actions.

The TopicFilter is the requested topic the client wishes to subscribe to.

The RequestedQoS is the client's preferred QoS level.

ReturnCode is used to confirm the maximum QoS level granted for this subscription or indicate a failure. This can be less than the client's RequestedQoS.

0x00 Success - Maximum QoS 0
0x01 Success - Maximum QoS 1
0x02 Success - Maximum QoS 2
0x80 Failure

Unsubscribe Event (MQTTBroker Component)

Fires when a client unsubscribes from a topic, removing its subscription data.

Syntax

public event OnUnsubscribeHandler OnUnsubscribe;

public delegate void OnUnsubscribeHandler(object sender, MQTTBrokerUnsubscribeEventArgs e);

public class MQTTBrokerUnsubscribeEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ClientId { get; }
  public string TopicFilter { get; }
}
Public Event OnUnsubscribe As OnUnsubscribeHandler

Public Delegate Sub OnUnsubscribeHandler(sender As Object, e As MQTTBrokerUnsubscribeEventArgs)

Public Class MQTTBrokerUnsubscribeEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ClientId As String
  Public ReadOnly Property TopicFilter As String
End Class

Remarks

The TopicFilter shows the topic this client is unsubscribing from.

MQTTBrokerConnection Type

This is a currently connected client.

Remarks

This type describes the connection of a client that is currently connected to the component. You may use the different fields of this type to manage the connection.

The following fields are available:

Fields

ClientId
string (read-only)

Default: ""

A unique identifier for the client.

ConnectionId
string (read-only)

Default: ""

This field contains an identifier generated by the component to identify each connection. This identifier is unique to this connection.

KeepAlive
int (read-only)

Default: 0

When set to 1, KEEPALIVE packets are enabled (for long connections).

This property enables the SO_KEEPALIVE option on the incoming connections. This option prevents long connections from timing out in case of inactivity.

Note: System Transmission Control Protocol (TCP)/IP stack implementations are not required to support SO_KEEPALIVE.

This property is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

LocalHost
string (read-only)

Default: ""

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

LocalAddress is important for multihomed hosts so that it can be used to find the particular network interface through which an individual connection is going.

LocalPort
int (read-only)

Default: 0

This field shows the Transmission Control Protocol (TCP) port on the local host through which the connection is passing.

Protocol
MQTTBrokerProtocols (read-only)

Default: 0

The protocol of the connected client.

The component supports the following protocols:

0 (mbpTCP) Plaintext TCP
1 (mbpTLS) SSL/TLS over TCP
2 (mbpWS) Plaintext WebSocket
3 (mbpWSS) SSL/TLS over WebSocket

RemoteHost
string (read-only)

Default: ""

This field 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 component 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.

RemotePort
int (read-only)

Default: 0

This field shows the Transmission Control Protocol (TCP) port on the remote host through which the connection is coming.

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

UserName
string (read-only)

Default: ""

The username for this connected client.

Constructors

MQTTBrokerListener Type

This represents a broker listener.

Remarks

Multiple listeners can be configured to listen on different ports and protocols..

The following fields are available:

Fields

LocalHost
string (read-only)

Default: ""

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

LocalPort
int (read-only)

Default: 0

This field includes the port in the local host for this listener.

Protocol
MQTTBrokerProtocols (read-only)

Default: 0

The component supports the following protocols:

0 (mbpTCP) Plaintext TCP
1 (mbpTLS) SSL/TLS over TCP
2 (mbpWS) Plaintext WebSocket
3 (mbpWSS) SSL/TLS over WebSocket

SSLAuthenticateClients
bool (read-only)

Default: False

If set to True, the server asks the client(s) for a certificate.

This is used in conjunction with the SSLClientAuthentication event. Please refer to the documentation of the SSLClientAuthentication event for details.

SSLCertStore
string (read-only)

Default: "MY"

The name of the certificate store for the listener's certificate.

The StoreType field 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 field 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 field for details.

Designations of certificate stores are platform dependent.

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

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

SSLCertStoreB
byte [] (read-only)

Default: "MY"

The name of the certificate store for the listener's certificate.

The StoreType field 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 field 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 field for details.

Designations of certificate stores are platform dependent.

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

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

SSLCertStorePassword
string (read-only)

Default: ""

This is the password of the SSL certificate.

SSLCertStoreType
CertStoreTypes (read-only)

Default: 0

This is the type of certificate store for this certificate.

Designations of certificate stores are platform dependent.

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

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

SSLCertSubject
string (read-only)

Default: ""

The subject of the SSL certificate.

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 as follows:

FieldMeaning
CNCommon Name. This is commonly a hostname like www.server.com.
OOrganization
OUOrganizational Unit
LLocality
SState
CCountry
EEmail Address

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

Constructors

MQTTBrokerMessage Type

An MQTT message.

Remarks

This type represents an MQTT message.

The following fields are available:

Fields

MessageId
long (read-only)

Default: 0

Message identifier used to associate the message state.

Payload
string (read-only)

Default: ""

This message's raw data payload.

PayloadB
byte [] (read-only)

Default: ""

This message's raw data payload.

Topic
string (read-only)

Default: ""

This message's topic.

Constructors

MQTTBrokerSession Type

Information for the client session.

Remarks

This contains session information for a client.

The following fields are available:

Fields

ClientId
string (read-only)

Default: ""

A unique identifier for the client.

IncomingMessages
string (read-only)

Default: ""

A collection of incoming messages.

OutgoingMessages
string (read-only)

Default: ""

A collection of outgoing messages.

SubGrantedQoS
string (read-only)

Default: ""

The subscription's granted QoS level for the client.

SubTopicFilters
string (read-only)

Default: ""

The subscription topic filters for this client session.

Constructors

Config Settings (MQTTBroker Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

TCPClient Config Settings

CloseStreamAfterTransfer:   If true, the component will close the upload or download stream after the transfer.

This configuration setting determines whether the input or output stream is closed after the transfer completes. When set to True (default), all streams will be closed after a transfer is completed. To keep streams open after the transfer of data, set this to False. The default value is True.

ConnectionTimeout:   Sets a separate timeout value for establishing a connection.

When set, this configuration setting allows you to specify a different timeout value for establishing a connection. Otherwise, the component will use Timeout for establishing a connection and transmitting/receiving data.

FirewallAutoDetect:   Tells the component whether or not to automatically detect and use firewall system settings, if available.

This configuration setting is provided for use by components that do not directly expose Firewall properties.

FirewallHost:   Name or IP address of firewall (optional).

If a FirewallHost is given, requested connections will be authenticated through the specified firewall when connecting.

If the FirewallHost setting is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, the FirewallHost setting is set to the corresponding address. If the search is not successful, an error is returned.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallListener:   If true, the component binds to a SOCKS firewall as a server (TCPClient only).

This entry is for TCPClient only and does not work for other components that descend from TCPClient.

If this entry is set, the component acts as a server. RemoteHost and RemotePort are used to tell the SOCKS firewall in which address and port to listen to. The firewall rules may ignore RemoteHost, and it is recommended that RemoteHost be set to empty string in this case.

RemotePort is the port in which the firewall will listen to. If set to 0, the firewall will select a random port. The binding (address and port) is provided through the ConnectionStatus event.

The connection to the firewall is made by calling the Connect method.

FirewallPassword:   Password to be used if authentication is to be used when connecting through the firewall.

If FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the given firewall. If the authentication fails, the component throws an exception.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallPort:   The TCP port for the FirewallHost;.

The FirewallPort is set automatically when FirewallType is set to a valid value.

Note: This configuration setting is provided for use by components that do not directly expose Firewall properties.

FirewallType:   Determines the type of firewall to connect through.

Possible values are as follows:

0No firewall (default setting).
1Connect through a tunneling proxy. FirewallPort is set to 80.
2Connect through a SOCKS4 Proxy. FirewallPort is set to 1080.
3Connect through a SOCKS5 Proxy. FirewallPort is set to 1080.
10Connect through a SOCKS4A Proxy. FirewallPort is set to 1080.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallUser:   A user name if authentication is to be used connecting through a firewall.

If the FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the Firewall. If the authentication fails, the component throws an exception.

Note: This setting is provided for use by components that do not directly expose Firewall properties.

KeepAliveInterval:   The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.

When set, TCPKeepAlive will automatically be set to True. A TCP keep-alive packet will be sent after a period of inactivity as defined by KeepAliveTime. If no acknowledgment is received from the remote host, the keep-alive packet will be sent again. This configuration setting specifies the interval at which the successive keep-alive packets are sent in milliseconds. This system default if this value is not specified here is 1 second.

Note: This value is not applicable in macOS.

KeepAliveTime:   The inactivity time in milliseconds before a TCP keep-alive packet is sent.

When set, TCPKeepAlive will automatically be set to True. By default, the operating system will determine the time a connection is idle before a Transmission Control Protocol (TCP) keep-alive packet is sent. This system default if this value is not specified here is 2 hours. In many cases, a shorter interval is more useful. Set this value to the desired interval in milliseconds.

Linger:   When set to True, connections are terminated gracefully.

This property controls how a connection is closed. The default is True.

In the case that Linger is True (default), two scenarios determine how long the connection will linger. In the first, if LingerTime is 0 (default), the system will attempt to send pending data for a connection until the default IP timeout expires.

In the second scenario, if LingerTime is a positive value, the system will attempt to send pending data until the specified LingerTime is reached. If this attempt fails, then the system will reset the connection.

The default behavior (which is also the default mode for stream sockets) might result in a long delay in closing the connection. Although the component returns control immediately, the system could hold system resources until all pending data are sent (even after your application closes).

Setting this property to False forces an immediate disconnection. If you know that the other side has received all the data you sent (e.g., by a client acknowledgment), setting this property to False might be the appropriate course of action.

LingerTime:   Time in seconds to have the connection linger.

LingerTime is the time, in seconds, the socket connection will linger. This value is 0 by default, which means it will use the default IP timeout.

LocalHost:   The name of the local host through which connections are initiated or accepted.

The LocalHost setting 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 multihomed hosts (machines with more than one IP interface), setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost setting 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 multihomed hosts (machines with more than one IP interface).

LocalPort:   The port in the local host where the component binds.

This configuration setting must be set before a connection is attempted. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.

This configuration setting is useful when trying to connect to services that require a trusted port on the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxLineLength:   The maximum amount of data to accumulate when no EOL is found.

MaxLineLength is the size of an internal buffer, which holds received data while waiting for an EOL string.

If an EOL string is found in the input stream before MaxLineLength bytes are received, the DataIn event is fired with the EOL parameter set to True, and the buffer is reset.

If no EOL is found, and MaxLineLength bytes are accumulated in the buffer, the DataIn event is fired with the EOL parameter set to False, and the buffer is reset.

The minimum value for MaxLineLength is 256 bytes. The default value is 2048 bytes.

MaxTransferRate:   The transfer rate limit in bytes per second.

This configuration setting can be used to throttle outbound TCP traffic. Set this to the number of bytes to be sent per second. By default, this is not set and there is no limit.

ProxyExceptionsList:   A semicolon separated list of hosts and IPs to bypass when using a proxy.

This configuration setting optionally specifies a semicolon-separated list of hostnames or IP addresses to bypass when a proxy is in use. When requests are made to hosts specified in this property, the proxy will not be used. For instance:

www.google.com;www.nsoftware.com

TCPKeepAlive:   Determines whether or not the keep alive socket option is enabled.

If set to True, the socket's keep-alive option is enabled and keep-alive packets will be sent periodically to maintain the connection. Set KeepAliveTime and KeepAliveInterval to configure the timing of the keep-alive packets.

Note: This value is not applicable in Java.

TcpNoDelay:   Whether or not to delay when sending packets.

When set to True, the socket will send all data that are ready to send at once. When set to False, the socket will send smaller buffered packets of data at small intervals. This is known as the Nagle algorithm.

By default, this configuration setting is set to False.

UseIPv6:   Whether to use IPv6.

When set to 0 (default), the component will use IPv4 exclusively. When set to 1, the component will use IPv6 exclusively. To instruct the component to prefer IPv6 addresses, but use IPv4 if IPv6 is not supported on the system, this setting should be set to 2. The default value is 0. Possible values are as follows:

0 IPv4 only
1 IPv6 only
2 IPv6 with IPv4 fallback
UseNTLMv2:   Whether to use NTLM V2.

When authenticating with NTLM, this setting specifies whether NTLM V2 is used. By default this value is False and NTLM V1 will be used. Set this to True to use NTLM V2.

SSL Config Settings

CACertFilePaths:   The paths to CA certificate files when using Mono on Unix/Linux.

This configuration setting specifies the paths on disk to certificate authority (CA) certificate files when using Mono on Unix/Linux. It is not applicable in any other circumstances.

The value is formatted as a list of paths separated by semicolons. The component will check for the existence of each file in the order specified. When a file is found, the CA certificates within the file will be loaded and used to determine the validity of server or client certificates.

The default value is as follows:

/etc/ssl/ca-bundle.pem;/etc/pki/tls/certs/ca-bundle.crt;/etc/ssl/certs/ca-certificates.crt;/etc/pki/tls/cacert.pem

LogSSLPackets:   Controls whether SSL packets are logged when using the internal security API.

When SSLProvider is set to Internal, this configuration setting controls whether Secure Sockets Layer (SSL) packets should be logged. By default, this configuration setting is False, as it is useful only for debugging purposes.

When enabled, SSL packet logs are output using the SSLStatus event, which will fire each time an SSL packet is sent or received.

Enabling this configuration setting has no effect if SSLProvider is set to Platform.

ReuseSSLSession:   Determines if the SSL session is reused.

If set to True, the component will reuse the context if and only if the following criteria are met:

  • The target host name is the same.
  • The system cache entry has not expired (default timeout is 10 hours).
  • The application process that calls the function is the same.
  • The logon session is the same.
  • The instance of the component is the same.

SSLCACerts:   A newline separated list of CA certificates to be included when performing an SSL handshake.

When SSLProvider is set to Internal, this configuration setting specifies one or more CA certificates to be included with the SSLCert property. Some servers or clients require the entire chain, including CA certificates, to be presented when performing SSL authentication. The value of this configuration setting is a newline-separated (CR/LF) list of certificates. For instance:

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

SSLCheckCRL:   Whether to check the Certificate Revocation List for the server certificate.

This configuration setting specifies whether the component will check the Certificate Revocation List (CRL) specified by the server certificate. If set to 1 or 2, the component will first obtain the list of CRL URLs from the server certificate's CRL distribution points extension. The component will then make HTTP requests to each CRL endpoint to check the validity of the server's certificate. If the certificate has been revoked or any other issues are found during validation the component throws an exception.

When set to 0 (default), the CRL check will not be performed by the component. When set to 1, it will attempt to perform the CRL check, but it will continue without an error if the server's certificate does not support CRL. When set to 2, it will perform the CRL check and will throw an error if CRL is not supported.

This configuration setting is supported only in the Java, C#, and C++ editions. In the C++ edition, it is supported only on Windows operating systems.

SSLCheckOCSP:   Whether to use OCSP to check the status of the server certificate.

This configuration setting specifies whether the component will use OCSP to check the validity of the server certificate. If set to 1 or 2, the component will first obtain the Online Certificate Status Protocol (OCSP) URL from the server certificate's OCSP extension. The component will then locate the issuing certificate and make an HTTP request to the OCSP endpoint to check the validity of the server's certificate. If the certificate has been revoked or any other issues are found during validation, the component throws an exception.

When set to 0 (default), the component will not perform an OCSP check. When set to 1, it will attempt to perform the OCSP check, but it will continue without an error if the server's certificate does not support OCSP. When set to 2, it will perform the OCSP check and will throw an error if OCSP is not supported.

This configuration setting is supported only in the Java, C#, and C++ editions. In the C++ edition, it is supported only on Windows operating systems.

SSLCipherStrength:   The minimum cipher strength used for bulk encryption.

This minimum cipher strength is largely dependent on the security modules installed on the system. If the cipher strength specified is not supported, an error will be returned when connections are initiated.

Note: This configuration setting contains the minimum cipher strength requested from the security library. The actual cipher strength used for the connection is shown by the SSLStatus event.

Use this configuration setting with caution. Requesting a lower cipher strength than necessary could potentially cause serious security vulnerabilities in your application.

When the provider is OpenSSL, SSLCipherStrength is currently not supported. This functionality is instead made available through the OpenSSLCipherList configuration setting.

SSLClientCACerts:   A newline separated list of CA certificates to use during SSL client certificate validation.

This configuration setting is only applicable to server components (e.g., TCPServer) see SSLServerCACerts for client components (e.g., TCPClient). This setting can be used to optionally specify one or more CA certificates to be used when verifying the client certificate that is presented by the client during the SSL handshake when SSLAuthenticateClients is enabled. When verifying the client's certificate, the certificates trusted by the system will be used as part of the verification process. If the client's CA certificates are not installed to the trusted system store, they may be specified here so they are included when performing the verification process. This configuration setting should be set only if the client's CA certificates are not already trusted on the system and cannot be installed to the trusted system store.

The value of this configuration setting is a newline-separated (CR/LF) list of certificates. For instance:

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert ...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert ...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

SSLEnabledCipherSuites:   The cipher suite to be used in an SSL negotiation.

This configuration setting enables the cipher suites to be used in SSL negotiation.

By default, the enabled cipher suites will include all available ciphers ("*").

The special value "*" means that the component will pick all of the supported cipher suites. If SSLEnabledCipherSuites is set to any other value, only the specified cipher suites will be considered.

Multiple cipher suites are separated by semicolons.

Example values when SSLProvider is set to Platform include the following: obj.config("SSLEnabledCipherSuites=*"); obj.config("SSLEnabledCipherSuites=CALG_AES_256"); obj.config("SSLEnabledCipherSuites=CALG_AES_256;CALG_3DES"); Possible values when SSLProvider is set to Platform include the following:

  • CALG_3DES
  • CALG_3DES_112
  • CALG_AES
  • CALG_AES_128
  • CALG_AES_192
  • CALG_AES_256
  • CALG_AGREEDKEY_ANY
  • CALG_CYLINK_MEK
  • CALG_DES
  • CALG_DESX
  • CALG_DH_EPHEM
  • CALG_DH_SF
  • CALG_DSS_SIGN
  • CALG_ECDH
  • CALG_ECDH_EPHEM
  • CALG_ECDSA
  • CALG_ECMQV
  • CALG_HASH_REPLACE_OWF
  • CALG_HUGHES_MD5
  • CALG_HMAC
  • CALG_KEA_KEYX
  • CALG_MAC
  • CALG_MD2
  • CALG_MD4
  • CALG_MD5
  • CALG_NO_SIGN
  • CALG_OID_INFO_CNG_ONLY
  • CALG_OID_INFO_PARAMETERS
  • CALG_PCT1_MASTER
  • CALG_RC2
  • CALG_RC4
  • CALG_RC5
  • CALG_RSA_KEYX
  • CALG_RSA_SIGN
  • CALG_SCHANNEL_ENC_KEY
  • CALG_SCHANNEL_MAC_KEY
  • CALG_SCHANNEL_MASTER_HASH
  • CALG_SEAL
  • CALG_SHA
  • CALG_SHA1
  • CALG_SHA_256
  • CALG_SHA_384
  • CALG_SHA_512
  • CALG_SKIPJACK
  • CALG_SSL2_MASTER
  • CALG_SSL3_MASTER
  • CALG_SSL3_SHAMD5
  • CALG_TEK
  • CALG_TLS1_MASTER
  • CALG_TLS1PRF
Example values when SSLProvider is set to Internalinclude the following: obj.config("SSLEnabledCipherSuites=*"); obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA"); obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA;TLS_ECDH_RSA_WITH_AES_128_CBC_SHA"); Possible values when SSLProvider is set to Internal include the following:
  • TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
  • TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
  • TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
  • TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
  • TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384
  • TLS_RSA_WITH_AES_256_GCM_SHA384
  • TLS_RSA_WITH_AES_128_GCM_SHA256
  • TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256
  • TLS_DHE_DSS_WITH_AES_256_GCM_SHA384
  • TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
  • TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
  • TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256
  • TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
  • TLS_DHE_DSS_WITH_AES_128_GCM_SHA256
  • TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
  • TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
  • TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384
  • TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
  • TLS_RSA_WITH_AES_256_CBC_SHA256
  • TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
  • TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384
  • TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
  • TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
  • TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
  • TLS_RSA_WITH_AES_128_CBC_SHA256
  • TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256
  • TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256
  • TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
  • TLS_RSA_WITH_AES_256_CBC_SHA
  • TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
  • TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
  • TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA
  • TLS_DHE_RSA_WITH_AES_256_CBC_SHA
  • TLS_ECDH_RSA_WITH_AES_256_CBC_SHA
  • TLS_DHE_DSS_WITH_AES_256_CBC_SHA
  • TLS_RSA_WITH_AES_128_CBC_SHA
  • TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
  • TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
  • TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA
  • TLS_ECDH_RSA_WITH_AES_128_CBC_SHA
  • TLS_DHE_RSA_WITH_AES_128_CBC_SHA
  • TLS_DHE_DSS_WITH_AES_128_CBC_SHA
  • TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA
  • TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA
  • TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA
  • TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA
  • TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
  • TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
  • TLS_RSA_WITH_3DES_EDE_CBC_SHA
  • TLS_RSA_WITH_DES_CBC_SHA
  • TLS_DHE_RSA_WITH_DES_CBC_SHA
  • TLS_DHE_DSS_WITH_DES_CBC_SHA
  • TLS_RSA_WITH_RC4_128_MD5
  • TLS_RSA_WITH_RC4_128_SHA

When TLS 1.3 is negotiated (see SSLEnabledProtocols), only the following cipher suites are supported:

  • TLS_AES_256_GCM_SHA384
  • TLS_CHACHA20_POLY1305_SHA256
  • TLS_AES_128_GCM_SHA256

SSLEnabledCipherSuites is used together with SSLCipherStrength.

SSLEnabledProtocols:   Used to enable/disable the supported security protocols.

This configuration setting is used to enable or disable the supported security protocols.

Not all supported protocols are enabled by default. The default value is 4032 for client components, and 3072 for server components. To specify a combination of enabled protocol versions set this config to the binary OR of one or more of the following values:

TLS1.312288 (Hex 3000)
TLS1.23072 (Hex C00) (Default - Client and Server)
TLS1.1768 (Hex 300) (Default - Client)
TLS1 192 (Hex C0) (Default - Client)
SSL3 48 (Hex 30)
SSL2 12 (Hex 0C)

Note that only TLS 1.2 is enabled for server components that accept incoming connections. This adheres to industry standards to ensure a secure connection. Client components enable TLS 1.0, TLS 1.1, and TLS 1.2 by default and will negotiate the highest mutually supported version when connecting to a server, which should be TLS 1.2 in most cases.

SSLEnabledProtocols: Transport Layer Security (TLS) 1.3 Notes:

By default when TLS 1.3 is enabled, the component will use the internal TLS implementation when the SSLProvider is set to Automatic for all editions.

In editions that are designed to run on Windows, SSLProvider can be set to Platform to use the platform implementation instead of the internal implementation. When configured in this manner, please note that the platform provider is supported only on Windows 11/Windows Server 2022 and up. The default internal provider is available on all platforms and is not restricted to any specific OS version.

If set to 1 (Platform provider), please be aware of the following notes:

  • The platform provider is available only on Windows 11/Windows Server 2022 and up.
  • SSLEnabledCipherSuites and other similar SSL configuration settings are not supported.
  • If SSLEnabledProtocols includes both TLS 1.3 and TLS 1.2, these restrictions are still applicable even if TLS 1.2 is negotiated. Enabling TLS 1.3 with the platform provider changes the implementation used for all TLS versions.

SSLEnabledProtocols: SSL2 and SSL3 Notes:

SSL 2.0 and 3.0 are not supported by the component when the SSLProvider is set to internal. To use SSL 2.0 or SSL 3.0, the platform security API must have the protocols enabled and SSLProvider needs to be set to platform.

SSLEnableRenegotiation:   Whether the renegotiation_info SSL extension is supported.

This configuration setting specifies whether the renegotiation_info SSL extension will be used in the request when using the internal security API. This configuration setting is false by default, but it can be set to true to enable the extension.

This configuration setting is applicable only when SSLProvider is set to Internal.

SSLIncludeCertChain:   Whether the entire certificate chain is included in the SSLServerAuthentication event.

This configuration setting specifies whether the Encoded parameter of the SSLServerAuthentication event contains the full certificate chain. By default this value is False and only the leaf certificate will be present in the Encoded parameter of the SSLServerAuthentication event.

If set to True, all certificates returned by the server will be present in the Encoded parameter of the SSLServerAuthentication event. This includes the leaf certificate, any intermediate certificate, and the root certificate.

Note: When SSLProvider is set to Internal this value is automatically set to true. This is needed for proper validation when using the internal provider.

SSLKeyLogFile:   The location of a file where per-session secrets are written for debugging purposes.

This configuration setting optionally specifies the full path to a file on disk where per-session secrets are stored for debugging purposes.

When set, the component will save the session secrets in the same format as the SSLKEYLOGFILE environment variable functionality used by most major browsers and tools, such as Chrome, Firefox, and cURL. This file can then be used in tools such as Wireshark to decrypt TLS traffic for debugging purposes. When writing to this file, the component will only append, it will not overwrite previous values.

Note: This configuration setting is applicable only when SSLProvider is set to Internal.

SSLNegotiatedCipher:   Returns the negotiated cipher suite.

This configuration setting returns the cipher suite negotiated during the SSL handshake.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedCipher[connId]");

SSLNegotiatedCipherStrength:   Returns the negotiated cipher suite strength.

This configuration setting returns the strength of the cipher suite negotiated during the SSL handshake.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedCipherStrength[connId]");

SSLNegotiatedCipherSuite:   Returns the negotiated cipher suite.

This configuration setting returns the cipher suite negotiated during the SSL handshake represented as a single string.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedCipherSuite[connId]");

SSLNegotiatedKeyExchange:   Returns the negotiated key exchange algorithm.

This configuration setting returns the key exchange algorithm negotiated during the SSL handshake.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedKeyExchange[connId]");

SSLNegotiatedKeyExchangeStrength:   Returns the negotiated key exchange algorithm strength.

This configuration setting returns the strength of the key exchange algorithm negotiated during the SSL handshake.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedKeyExchangeStrength[connId]");

SSLNegotiatedVersion:   Returns the negotiated protocol version.

This configuration setting returns the protocol version negotiated during the SSL handshake.

Note: For server components (e.g., TCPServer), this is a per-connection configuration setting accessed by passing the ConnectionId. For example: server.Config("SSLNegotiatedVersion[connId]");

SSLSecurityFlags:   Flags that control certificate verification.

The following flags are defined (specified in hexadecimal notation). They can be ORed together to exclude multiple conditions:

0x00000001Ignore time validity status of certificate.
0x00000002Ignore time validity status of CTL.
0x00000004Ignore non-nested certificate times.
0x00000010Allow unknown certificate authority.
0x00000020Ignore wrong certificate usage.
0x00000100Ignore unknown certificate revocation status.
0x00000200Ignore unknown CTL signer revocation status.
0x00000400Ignore unknown certificate authority revocation status.
0x00000800Ignore unknown root revocation status.
0x00008000Allow test root certificate.
0x00004000Trust test root certificate.
0x80000000Ignore non-matching CN (certificate CN non-matching server name).

This functionality is currently not available in Java or when the provider is OpenSSL.

SSLServerCACerts:   A newline separated list of CA certificates to use during SSL server certificate validation.

This configuration setting is only used by client components (e.g., TCPClient) see SSLClientCACerts for server components (e.g., TCPServer). This configuration setting can be used to optionally specify one or more CA certificates to be used when connecting to the server and verifying the server certificate. When verifying the server's certificate, the certificates trusted by the system will be used as part of the verification process. If the server's CA certificates are not installed to the trusted system store, they may be specified here so they are included when performing the verification process. This configuration setting should be set only if the server's CA certificates are not already trusted on the system and cannot be installed to the trusted system store.

The value of this configuration setting is a newline-separated (CR/LF) list of certificates. For instance:

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
... Intermediate Cert...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
... Root Cert...
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

TLS12SignatureAlgorithms:   Defines the allowed TLS 1.2 signature algorithms when SSLProvider is set to Internal.

This configuration setting specifies the allowed server certificate signature algorithms when SSLProvider is set to Internal and SSLEnabledProtocols is set to allow TLS 1.2.

When specified the component will verify that the server certificate signature algorithm is among the values specified in this configuration setting. If the server certificate signature algorithm is unsupported, the component throws an exception.

The format of this value is a comma-separated list of hash-signature combinations. For instance: component.SSLProvider = TCPClientSSLProviders.sslpInternal; component.Config("SSLEnabledProtocols=3072"); //TLS 1.2 component.Config("TLS12SignatureAlgorithms=sha256-rsa,sha256-dsa,sha1-rsa,sha1-dsa"); The default value for this configuration setting is sha512-ecdsa,sha512-rsa,sha512-dsa,sha384-ecdsa,sha384-rsa,sha384-dsa,sha256-ecdsa,sha256-rsa,sha256-dsa,sha224-ecdsa,sha224-rsa,sha224-dsa,sha1-ecdsa,sha1-rsa,sha1-dsa.

To not restrict the server's certificate signature algorithm, specify an empty string as the value for this configuration setting, which will cause the signature_algorithms TLS 1.2 extension to not be sent.

TLS12SupportedGroups:   The supported groups for ECC.

This configuration setting specifies a comma-separated list of named groups used in TLS 1.2 for ECC.

The default value is ecdhe_secp256r1,ecdhe_secp384r1,ecdhe_secp521r1.

When using TLS 1.2 and SSLProvider is set to Internal, the values refer to the supported groups for ECC. The following values are supported:

  • "ecdhe_secp256r1" (default)
  • "ecdhe_secp384r1" (default)
  • "ecdhe_secp521r1" (default)

TLS13KeyShareGroups:   The groups for which to pregenerate key shares.

This configuration setting specifies a comma-separated list of named groups used in TLS 1.3 for key exchange. The groups specified here will have key share data pregenerated locally before establishing a connection. This can prevent an additional roundtrip during the handshake if the group is supported by the server.

The default value is set to balance common supported groups and the computational resources required to generate key shares. As a result, only some groups are included by default in this configuration setting.

Note: All supported groups can always be used during the handshake even if not listed here, but if a group is used that is not present in this list, it will incur an additional roundtrip and time to generate the key share for that group.

In most cases, this configuration setting does not need to be modified. This should be modified only if there is a specific reason to do so.

The default value is ecdhe_x25519,ecdhe_secp256r1,ecdhe_secp384r1,ffdhe_2048,ffdhe_3072

The values are ordered from most preferred to least preferred. The following values are supported:

  • "ecdhe_x25519" (default)
  • "ecdhe_x448"
  • "ecdhe_secp256r1" (default)
  • "ecdhe_secp384r1" (default)
  • "ecdhe_secp521r1"
  • "ffdhe_2048" (default)
  • "ffdhe_3072" (default)
  • "ffdhe_4096"
  • "ffdhe_6144"
  • "ffdhe_8192"

TLS13SignatureAlgorithms:   The allowed certificate signature algorithms.

This configuration setting holds a comma-separated list of allowed signature algorithms. Possible values include the following:

  • "ed25519" (default)
  • "ed448" (default)
  • "ecdsa_secp256r1_sha256" (default)
  • "ecdsa_secp384r1_sha384" (default)
  • "ecdsa_secp521r1_sha512" (default)
  • "rsa_pkcs1_sha256" (default)
  • "rsa_pkcs1_sha384" (default)
  • "rsa_pkcs1_sha512" (default)
  • "rsa_pss_sha256" (default)
  • "rsa_pss_sha384" (default)
  • "rsa_pss_sha512" (default)
The default value is rsa_pss_sha256,rsa_pss_sha384,rsa_pss_sha512,rsa_pkcs1_sha256,rsa_pkcs1_sha384,rsa_pkcs1_sha512,ecdsa_secp256r1_sha256,ecdsa_secp384r1_sha384,ecdsa_secp521r1_sha512,ed25519,ed448. This configuration setting is applicable only when SSLEnabledProtocols includes TLS 1.3.
TLS13SupportedGroups:   The supported groups for (EC)DHE key exchange.

This configuration setting specifies a comma-separated list of named groups used in TLS 1.3 for key exchange. This configuration setting should be modified only if there is a specific reason to do so.

The default value is ecdhe_x25519,ecdhe_x448,ecdhe_secp256r1,ecdhe_secp384r1,ecdhe_secp521r1,ffdhe_2048,ffdhe_3072,ffdhe_4096,ffdhe_6144,ffdhe_8192

The values are ordered from most preferred to least preferred. The following values are supported:

  • "ecdhe_x25519" (default)
  • "ecdhe_x448" (default)
  • "ecdhe_secp256r1" (default)
  • "ecdhe_secp384r1" (default)
  • "ecdhe_secp521r1" (default)
  • "ffdhe_2048" (default)
  • "ffdhe_3072" (default)
  • "ffdhe_4096" (default)
  • "ffdhe_6144" (default)
  • "ffdhe_8192" (default)

Socket Config Settings

AbsoluteTimeout:   Determines whether timeouts are inactivity timeouts or absolute timeouts.

If AbsoluteTimeout is set to True, any method that does not complete within Timeout seconds will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.

Note: This option is not valid for User Datagram Protocol (UDP) ports.

FirewallData:   Used to send extra data to the firewall.

When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g., headers for custom authentication schemes).

InBufferSize:   The size in bytes of the incoming queue of the socket.

This is the size of an internal queue in the Transmission Control Protocol (TCP)/IP stack. You can increase or decrease its size depending on the amount of data that you will be receiving. In some cases, increasing the value of the InBufferSize setting can provide significant improvements in performance.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

OutBufferSize:   The size in bytes of the outgoing queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be sending. In some cases, increasing the value of the OutBufferSize setting can provide significant improvements in performance.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

Base Config Settings

BuildInfo:   Information about the product's build.

When queried, this setting will return a string containing information about the product's build.

GUIAvailable:   Whether or not a message loop is available for processing events.

In a GUI-based application, long-running blocking operations may cause the application to stop responding to input until the operation returns. The component will attempt to discover whether or not the application has a message loop and, if one is discovered, it will process events in that message loop during any such blocking operation.

In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the component does not attempt to process external events.

LicenseInfo:   Information about the current license.

When queried, this setting will return a string containing information about the license this instance of a component is using. It will return the following information:

  • Product: The product the license is for.
  • Product Key: The key the license was generated from.
  • License Source: Where the license was found (e.g., RuntimeLicense, License File).
  • License Type: The type of license installed (e.g., Royalty Free, Single Server).
  • Last Valid Build: The last valid build number for which the license will work.
MaskSensitiveData:   Whether sensitive data is masked in log messages.

In certain circumstances it may be beneficial to mask sensitive data, like passwords, in log messages. Set this to true to mask sensitive data. The default is true.

This setting only works on these components: AS3Receiver, AS3Sender, Atom, Client(3DS), FTP, FTPServer, IMAP, OFTPClient, SSHClient, SCP, Server(3DS), Sexec, SFTP, SFTPServer, SSHServer, TCPClient, TCPServer.

UseFIPSCompliantAPI:   Tells the component whether or not to use FIPS certified APIs.

When set to true, the component will utilize the underlying operating system's certified APIs. Java editions, regardless of OS, utilize Bouncy Castle Federal Information Processing Standards (FIPS), while all other Windows editions make use of Microsoft security libraries.

FIPS mode can be enabled by setting the UseFIPSCompliantAPI configuration setting to true. This is a static setting that applies to all instances of all components of the toolkit within the process. It is recommended to enable or disable this setting once before the component has been used to establish a connection. Enabling FIPS while an instance of the component is active and connected may result in unexpected behavior.

For more details, please see the FIPS 140-2 Compliance article.

Note: This setting is applicable only on Windows.

Note: Enabling FIPS compliance requires a special license; please contact sales@nsoftware.com for details.

UseInternalSecurityAPI:   Whether or not to use the system security libraries or an internal implementation.

When set to false, the component will use the system security libraries by default to perform cryptographic functions where applicable. In this case, calls to unmanaged code will be made. In certain environments, this is not desirable. To use a completely managed security implementation, set this setting to true.

Setting this configuration setting to true tells the component to use the internal implementation instead of using the system security libraries.

On Windows, this setting is set to false by default. On Linux/macOS, this setting is set to true by default.

If using the .NET Standard Library, this setting will be true on all platforms. The .NET Standard library does not support using the system security libraries.

Note: This setting is static. The value set is applicable to all components used in the application.

When this value is set, the product's system dynamic link library (DLL) is no longer required as a reference, as all unmanaged code is stored in that file.

Trappable Errors (MQTTBroker Component)

MQTTBroker Errors

600   MQTT protocol error. Refer to the error message for more information.
601   Invalid topic name. Refer to the error message for more information.

TCPClient Errors

100   You cannot change the RemotePort at this time. A connection is in progress.
101   You cannot change the RemoteHost (Server) at this time. A connection is in progress.
102   The RemoteHost address is invalid (0.0.0.0).
104   Already connected. If you want to reconnect, close the current connection first.
106   You cannot change the LocalPort at this time. A connection is in progress.
107   You cannot change the LocalHost at this time. A connection is in progress.
112   You cannot change MaxLineLength at this time. A connection is in progress.
116   RemotePort cannot be zero. Please specify a valid service port number.
117   You cannot change the UseConnection option while the component is active.
135   Operation would block.
201   Timeout.
211   Action impossible in control's present state.
212   Action impossible while not connected.
213   Action impossible while listening.
301   Timeout.
303   Could not open file.
434   Unable to convert string to selected CodePage.
1105   Already connecting. If you want to reconnect, close the current connection first.
1117   You need to connect first.
1119   You cannot change the LocalHost at this time. A connection is in progress.
1120   Connection dropped by remote host.

SSL Errors

270   Cannot load specified security library.
271   Cannot open certificate store.
272   Cannot find specified certificate.
273   Cannot acquire security credentials.
274   Cannot find certificate chain.
275   Cannot verify certificate chain.
276   Error during handshake.
280   Error verifying certificate.
281   Could not find client certificate.
282   Could not find server certificate.
283   Error encrypting data.
284   Error decrypting data.

TCP/IP Errors

10004   [10004] Interrupted system call.
10009   [10009] Bad file number.
10013   [10013] Access denied.
10014   [10014] Bad address.
10022   [10022] Invalid argument.
10024   [10024] Too many open files.
10035   [10035] Operation would block.
10036   [10036] Operation now in progress.
10037   [10037] Operation already in progress.
10038   [10038] Socket operation on nonsocket.
10039   [10039] Destination address required.
10040   [10040] Message is too long.
10041   [10041] Protocol wrong type for socket.
10042   [10042] Bad protocol option.
10043   [10043] Protocol is not supported.
10044   [10044] Socket type is not supported.
10045   [10045] Operation is not supported on socket.
10046   [10046] Protocol family is not supported.
10047   [10047] Address family is not supported by protocol family.
10048   [10048] Address already in use.
10049   [10049] Cannot assign requested address.
10050   [10050] Network is down.
10051   [10051] Network is unreachable.
10052   [10052] Net dropped connection or reset.
10053   [10053] Software caused connection abort.
10054   [10054] Connection reset by peer.
10055   [10055] No buffer space available.
10056   [10056] Socket is already connected.
10057   [10057] Socket is not connected.
10058   [10058] Cannot send after socket shutdown.
10059   [10059] Too many references, cannot splice.
10060   [10060] Connection timed out.
10061   [10061] Connection refused.
10062   [10062] Too many levels of symbolic links.
10063   [10063] File name is too long.
10064   [10064] Host is down.
10065   [10065] No route to host.
10066   [10066] Directory is not empty
10067   [10067] Too many processes.
10068   [10068] Too many users.
10069   [10069] Disc Quota Exceeded.
10070   [10070] Stale NFS file handle.
10071   [10071] Too many levels of remote in path.
10091   [10091] Network subsystem is unavailable.
10092   [10092] WINSOCK DLL Version out of range.
10093   [10093] Winsock is not loaded yet.
11001   [11001] Host not found.
11002   [11002] Nonauthoritative 'Host not found' (try again or check DNS setup).
11003   [11003] Nonrecoverable errors: FORMERR, REFUSED, NOTIMP.
11004   [11004] Valid name, no data record (check DNS setup).