Telnet Component

Properties   Methods   Events   Config Settings   Errors  

The Telnet Component is used to communicate with servers implementing the TELNET protocol.

Syntax

nsoftware.IPWorksSSL.Telnet

Remarks

The Telnet Component supports both plaintext and SSL/TLS connections. When connecting over SSL/TLS the SSLServerAuthentication event allows you to check the server identity and other security attributes. The SSLStatus event provides information about the SSL handshake. Additional SSL related settings are also supported via the Config method.

The Telnet Component provides a simple interface to Telnet communications as specified by RFC 854. It allows sending of Telnet command codes to remote Telnet servers and it scans the input data for Telnet commands. Appropriate events are fired for received commands.

The connection interface is very similar to that of TCPClient. The same properties and events are used for sending and receiving normal data, and the same property set is used for setting properties of the connection. The Telnet Component adds a number of properties like Command, DoOption, etc. which allow sending of Telnet commands to the other end. The respective events (Command, Do, etc.) are fired when the corresponding Telnet commands are received.

Property List

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

Method List

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

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.

Config Settings

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

AcceptData Property (Telnet Component)

This property enables or disables data reception (the DataIn event).

Syntax

• C#
• VB.NET

public bool AcceptData { get; set; }

Public Property AcceptData As Boolean

Default Value

True

Remarks

This property enables or disables data reception (the DataIn event). Setting this property to False, temporarily disables data reception (and the DataIn event). Setting this property to True, reenables data reception.

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

This property is not available at design time.

BytesSent Property (Telnet Component)

The number of bytes actually sent after an assignment to DataToSend .

Syntax

• C#
• VB.NET

public int BytesSent { get; }

Public ReadOnly Property BytesSent As Integer

Default Value

0

Remarks

The BytesSent property shows how many bytes were sent after the last assignment to DataToSend or UrgentData. Please check the DataToSend property for more information.

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

Command Property (Telnet Component)

A single character Telnet command code to be sent to the server.

Syntax

• C#
• VB.NET

public int Command { set; }

Public WriteOnly Property Command As Integer

Default Value

0

Remarks

Codes for Telnet commands and their meanings are defined in the Telnet RFCs. Here are some examples:

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

Connected Property (Telnet Component)

Triggers a connection or disconnection.

Syntax

• C#
• VB.NET

public bool Connected { get; set; }

Public Property Connected As Boolean

Default Value

False

Remarks

Setting the Connected property to True makes the component attempt to connect to the host identified by the RemoteHost property. If successful, after the connection is achieved, the value of the property changes to True and the Connected event is fired.

Setting Connected to False closes the connection. How and when the connection is closed is controlled by the Linger property.

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

This property is not available at design time.

DataToSend Property (Telnet Component)

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

Syntax

• C#
• VB.NET

public string DataToSend { set; }
public byte[] DataToSendB { set; }

Public WriteOnly Property DataToSend As String
Public WriteOnly Property DataToSendB As Byte()

Default Value

""

Remarks

Assigning a string to the DataToSend property makes the component send the string to the remote host. The Send method provides similar functionality.

If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, the operation fails with exception 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again. . The BytesSent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the ReadyToSend event before attempting to send data again.

Note: The ReadyToSend event is not fired when part of the data is sent successfully.

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

DontOption Property (Telnet Component)

A single character Telnet option code to be sent to the server with the Telnet DONT command.

Syntax

• C#
• VB.NET

public int DontOption { set; }

Public WriteOnly Property DontOption As Integer

Default Value

0

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

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

DoOption Property (Telnet Component)

A single character Telnet option code to be sent to the server with the Telnet DO command.

Syntax

• C#
• VB.NET

public int DoOption { set; }

Public WriteOnly Property DoOption As Integer

Default Value

0

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

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

DoSubOption Property (Telnet Component)

A Telnet SubOption to send to the server with the SubOption command.

Syntax

• C#
• VB.NET

public string DoSubOption { set; }
public byte[] DoSubOptionB { set; }

Public WriteOnly Property DoSubOption As String
Public WriteOnly Property DoSubOptionB As Byte()

Default Value

""

Remarks

For a list of valid Telnet suboptions and their descriptions please look at the Telnet RFCs.

You don't need to specify the suboption start and suboption end codes. Those are appended automatically by the component. For example, to send a terminal type suboption to request setting the terminal type to 'vt100', you must send ASCII 24, followed by ASCII 0, followed by "vt100" (without the quotes).

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

Firewall Property (Telnet Component)

A set of properties related to firewall access.

Syntax

• C#
• VB.NET

public Firewall Firewall { get; set; }

Public Property Firewall As Firewall

Remarks

This is a Firewall type property which contains fields describing the firewall through which the component will attempt to connect.

KeepAlive Property (Telnet Component)

When True, KEEPALIVE packets are enabled (for long connections).

Syntax

• C#
• VB.NET

public bool KeepAlive { get; set; }

Public Property KeepAlive As Boolean

Default Value

False

Remarks

The KeepAlive enables the SO_KEEPALIVE option on the socket. 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.

Linger Property (Telnet Component)

When set to True, this property ensures that connections are terminated gracefully.

Syntax

• C#
• VB.NET

public bool Linger { get; set; }

Public Property Linger As Boolean

Default Value

True

Remarks

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.

LocalHost Property (Telnet Component)

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

Syntax

• C#
• VB.NET

public string LocalHost { get; set; }

Public Property LocalHost As String

Default Value

""

Remarks

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

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

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

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

LocalPort Property (Telnet Component)

The TCP port in the local host where TCPClient binds.

Syntax

• C#
• VB.NET

public int LocalPort { get; set; }

Public Property LocalPort As Integer

Default Value

0

Remarks

The LocalPort property 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 it to 0 (default) enables the TCP/IP stack to choose a port at random. The chosen port will be shown by the LocalPort property after the connection is established.

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

The LocalPort property is useful when trying to connect to services that require a trusted port in the client side.

RemoteHost Property (Telnet Component)

This property includes the address of the remote host. Domain names are resolved to IP addresses.

Syntax

• C#
• VB.NET

public string RemoteHost { get; set; }

Public Property RemoteHost As String

Default Value

""

Remarks

This property specifies the IP address (IP number in dotted internet format) or the domain name of the remote host. It is set before a connection is attempted and cannot be changed once a connection is established.

If this property is set to a domain name, a DNS request is initiated, and upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, an error is returned.

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.

Example. Connecting:

TCPClientControl.RemoteHost = "MyHostNameOrIP" TCPClientControl.RemotePort = 777 TCPClientControl.Connected = true

RemotePort Property (Telnet Component)

The secure Telnet port in the remote host (default is 23).

Syntax

• C#
• VB.NET

public int RemotePort { get; set; }

Public Property RemotePort As Integer

Default Value

23

Remarks

For implicit SSL, use port 992 (please refer to the SSLStartMode property for more information).

A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

This property is not available at design time.

SSLAcceptServerCert Property (Telnet Component)

Instructs the component to unconditionally accept the server certificate that matches the supplied certificate.

Syntax

• C#
• VB.NET

public Certificate SSLAcceptServerCert { get; set; }

Public Property SSLAcceptServerCert As Certificate

Remarks

If it finds any issues with the certificate presented by the server, the component will normally terminate the connection with an error.

You may override this behavior by supplying a value for SSLAcceptServerCert. If the certificate supplied in SSLAcceptServerCert is the same as the certificate presented by the server, then the server certificate is accepted unconditionally, and the connection will continue normally.

Please note that this functionality is provided only for cases where you otherwise know that you are communicating with the right server. If used improperly, this property may create a security breach. Use it at your own risk.

SSLCert Property (Telnet Component)

The certificate to be used during SSL negotiation.

Syntax

• C#
• VB.NET

public Certificate SSLCert { get; set; }

Public Property SSLCert As Certificate

Remarks

The digital certificate that the component will use during SSL negotiation. Set this property to a valid certificate before starting SSL negotiation. To set a certificate, you may set the Encoded field to the encoded certificate. To select a certificate, use the store and subject fields.

SSLProvider Property (Telnet Component)

This specifies the SSL/TLS implementation to use.

Syntax

• C#
• VB.NET

public TelnetSSLProviders SSLProvider { get; set; }

enum TelnetSSLProviders {
  sslpAutomatic,
  sslpPlatform,
  sslpInternal
}

Public Property SSLProvider As TelnetSSLProviders

Enum TelnetSSLProviders
  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:

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.

SSLServerCert Property (Telnet Component)

The server certificate for the last established connection.

Syntax

• C#
• VB.NET

public Certificate SSLServerCert { get; }

Public ReadOnly Property SSLServerCert As Certificate

Remarks

SSLServerCert contains the server certificate for the last established connection.

SSLServerCert is reset every time a new connection is attempted.

This property is read-only.

SSLStartMode Property (Telnet Component)

Determines how the component starts the SSL negotiation.

Syntax

• C#
• VB.NET

public TelnetSSLStartModes SSLStartMode { get; set; }

enum TelnetSSLStartModes {
  sslAutomatic,
  sslImplicit,
  sslExplicit
}

Public Property SSLStartMode As TelnetSSLStartModes

Enum TelnetSSLStartModes
  sslAutomatic
  sslImplicit
  sslExplicit
End Enum

Default Value

0

Remarks

The SSLStartMode property may have one of the following values:

Timeout Property (Telnet Component)

A timeout for the component.

Syntax

• C#
• VB.NET

public int Timeout { get; set; }

Public Property Timeout As Integer

Default Value

0

Remarks

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

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

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

If Timeout expires, and the operation is not yet complete, the component throws an exception.

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

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

Note: when a communication component behaves asynchronously in .NET, some events can fire from the background threads used to process socket IO. This can cause problems in GUI applications where there is logic inside an asynchronous event that interacts with the GUI. In .NET, most GUI controls will not allow themselves to be accessed from any thread other than the one that created them due to potential deadlocking issues. To ensure the user can do this, the .NET GUI API supplies a BeginInvoke method that can be used to access GUI controls from other threads, such as the ones that fire events. You can also set the InvokeThrough property of the communication component to any control on the GUI form to direct the component to forward all events through that control.

Transparent Property (Telnet Component)

When True, Telnet command processing is disabled.

Syntax

• C#
• VB.NET

public bool Transparent { get; set; }

Public Property Transparent As Boolean

Default Value

False

Remarks

The Transparent property allows you to enable or disable Telnet command processing. When command processing is disabled, any data received is provided with no modifications.

UrgentData Property (Telnet Component)

A string of data to be sent urgently (out-of-band) to the remote host.

Syntax

• C#
• VB.NET

public string UrgentData { set; }
public byte[] UrgentDataB { set; }

Public WriteOnly Property UrgentData As String
Public WriteOnly Property UrgentDataB As Byte()

Default Value

""

Remarks

The UrgentData property behaves exactly like the DataToSend property except that the data is sent Out Of Band (urgent). This means that the data assigned to UrgentData will bypass the normal TCP queuing mechanism. Use this property with caution.

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

WillOption Property (Telnet Component)

A single character Telnet option code to be sent to the server with the Telnet WILL command.

Syntax

• C#
• VB.NET

public int WillOption { set; }

Public WriteOnly Property WillOption As Integer

Default Value

0

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

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

WontOption Property (Telnet Component)

A single character Telnet option code to be sent to the server with the Telnet WONT command.

Syntax

• C#
• VB.NET

public int WontOption { set; }

Public WriteOnly Property WontOption As Integer

Default Value

0

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

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

Config Method (Telnet Component)

Sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

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.

Connect Method (Telnet Component)

Connects to a remote host.

Syntax

• C#
• VB.NET

public void Connect();

Async Version
public async Task Connect();
public async Task Connect(CancellationToken cancellationToken);

Public Sub Connect()

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

Remarks

This method connects to the remote host specified by RemoteHost. For instance: component.RemoteHost = "MyHostNameOrIP"; component.Connect();

To specify a non-standard port number set RemotePort before calling this method.

ConnectTo Method (Telnet Component)

Connects to a remote host.

Syntax

• C#
• VB.NET

public void ConnectTo(string host);

Async Version
public async Task ConnectTo(string host);
public async Task ConnectTo(string host, CancellationToken cancellationToken);

Public Sub ConnectTo(ByVal Host As String)

Async Version
Public Sub ConnectTo(ByVal Host As String) As Task
Public Sub ConnectTo(ByVal Host As String, cancellationToken As CancellationToken) As Task

Remarks

This method connects to the remote host specified by the Host. For instance: component.Connect("MyTelnetServer");

To specify a non-standard port number set RemotePort before calling this method.

Disconnect Method (Telnet Component)

Disconnect from the remote host.

Syntax

• C#
• VB.NET

public void Disconnect();

Async Version
public async Task Disconnect();
public async Task Disconnect(CancellationToken cancellationToken);

Public Sub Disconnect()

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

Remarks

Calling this method is equivalent to setting the Connected property to False.

DoEvents Method (Telnet Component)

Processes events from the internal message queue.

Syntax

• C#
• VB.NET

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.

PauseData Method (Telnet Component)

This method pauses data reception.

Syntax

• C#
• VB.NET

public void PauseData();

Async Version
public async Task PauseData();
public async Task PauseData(CancellationToken cancellationToken);

Public Sub PauseData()

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

Remarks

This method pauses data reception when called. While data reception is paused, the DataIn event will not fire. Call ProcessData to reenable data reception.

ProcessData Method (Telnet Component)

This method reenables data reception after a call to PauseData

Syntax

• C#
• VB.NET

public void ProcessData();

Async Version
public async Task ProcessData();
public async Task ProcessData(CancellationToken cancellationToken);

Public Sub ProcessData()

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

Remarks

This method reenables data reception after a previous call to PauseData. When PauseData is called, the DataIn event will not fire. To reenable data reception and allow DataIn to fire, call this method.

Note: This method is used only after previously calling PauseData. It does not need to be called to process incoming data by default.

Reset Method (Telnet Component)

Reset the component.

Syntax

• C#
• VB.NET

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.

Send Method (Telnet Component)

Sends binary data to the remote host.

Syntax

• C#
• VB.NET

public void Send(byte[] text);

Async Version
public async Task Send(byte[] text);
public async Task Send(byte[] text, CancellationToken cancellationToken);

Public Sub Send(ByVal Text As String)

Async Version
Public Sub Send(ByVal Text As String) As Task
Public Sub Send(ByVal Text As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends the specified binary data to the remote host. To send text use the SendText method instead.

SendBytes Method (Telnet Component)

Sends binary data to the remote host.

Syntax

• C#
• VB.NET

public void SendBytes(byte[] data);

Async Version
public async Task SendBytes(byte[] data);
public async Task SendBytes(byte[] data, CancellationToken cancellationToken);

Public Sub SendBytes(ByVal Data As String)

Async Version
Public Sub SendBytes(ByVal Data As String) As Task
Public Sub SendBytes(ByVal Data As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends the specified binary data to the remote host. To send text use the SendText method instead.

SendCommand Method (Telnet Component)

Sends a single character Telnet command code to the server.

Syntax

• C#
• VB.NET

public void SendCommand(int command);

Async Version
public async Task SendCommand(int command);
public async Task SendCommand(int command, CancellationToken cancellationToken);

Public Sub SendCommand(ByVal Command As Integer)

Async Version
Public Sub SendCommand(ByVal Command As Integer) As Task
Public Sub SendCommand(ByVal Command As Integer, cancellationToken As CancellationToken) As Task

Remarks

This method sends the single character command code specified by Command to the server. Codes for Telnet commands and their meanings are defined in the Telnet RFCs. Some common commands are:

SendDontOption Method (Telnet Component)

This method sends a single character Telnet option code to the server with the Telnet DONT command.

Syntax

• C#
• VB.NET

public void SendDontOption(int dontOption);

Async Version
public async Task SendDontOption(int dontOption);
public async Task SendDontOption(int dontOption, CancellationToken cancellationToken);

Public Sub SendDontOption(ByVal DontOption As Integer)

Async Version
Public Sub SendDontOption(ByVal DontOption As Integer) As Task
Public Sub SendDontOption(ByVal DontOption As Integer, cancellationToken As CancellationToken) As Task

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

SendDoOption Method (Telnet Component)

This method sends a single character Telnet option code to the server with the Telnet DO command.

Syntax

• C#
• VB.NET

public void SendDoOption(int doOption);

Async Version
public async Task SendDoOption(int doOption);
public async Task SendDoOption(int doOption, CancellationToken cancellationToken);

Public Sub SendDoOption(ByVal DoOption As Integer)

Async Version
Public Sub SendDoOption(ByVal DoOption As Integer) As Task
Public Sub SendDoOption(ByVal DoOption As Integer, cancellationToken As CancellationToken) As Task

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

SendDoSubOption Method (Telnet Component)

This methods sends a Telnet SubOption to send to the server with the SubOption command.

Syntax

• C#
• VB.NET

public void SendDoSubOption(byte[] doSubOption);

Async Version
public async Task SendDoSubOption(byte[] doSubOption);
public async Task SendDoSubOption(byte[] doSubOption, CancellationToken cancellationToken);

Public Sub SendDoSubOption(ByVal DoSubOption As String)

Async Version
Public Sub SendDoSubOption(ByVal DoSubOption As String) As Task
Public Sub SendDoSubOption(ByVal DoSubOption As String, cancellationToken As CancellationToken) As Task

Remarks

Valid suboptions and their descriptions are defined in the Telnet RFCs.

For example, to send a terminal type suboption to request setting the terminal type to 'vt100', send ASCII 24, followed by ASCII 0, followed by vt100.

Suboption start and end codes are automatically added by the component.

SendText Method (Telnet Component)

Sends text to the remote host.

Syntax

• C#
• VB.NET

public void SendText(string text);

Async Version
public async Task SendText(string text);
public async Task SendText(string text, CancellationToken cancellationToken);

Public Sub SendText(ByVal Text As String)

Async Version
Public Sub SendText(ByVal Text As String) As Task
Public Sub SendText(ByVal Text As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends the specified text to the remote host. To send binary data use the SendBytes method instead.

SendUrgentBytes Method (Telnet Component)

Urgently sends binary data to the remote host.

Syntax

• C#
• VB.NET

public void SendUrgentBytes(byte[] urgentBytes);

Async Version
public async Task SendUrgentBytes(byte[] urgentBytes);
public async Task SendUrgentBytes(byte[] urgentBytes, CancellationToken cancellationToken);

Public Sub SendUrgentBytes(ByVal UrgentBytes As String)

Async Version
Public Sub SendUrgentBytes(ByVal UrgentBytes As String) As Task
Public Sub SendUrgentBytes(ByVal UrgentBytes As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends the bytes specified by UrgentBytes as urgent data (out-of-band) to the remote host. To send text urgently use the SendUrgentText method instead.

Data sent using this method will bypass the normal TCP queuing mechanism. Use this method with caution.

SendUrgentText Method (Telnet Component)

Urgently sends text to the remote host.

Syntax

• C#
• VB.NET

public void SendUrgentText(string urgentText);

Async Version
public async Task SendUrgentText(string urgentText);
public async Task SendUrgentText(string urgentText, CancellationToken cancellationToken);

Public Sub SendUrgentText(ByVal UrgentText As String)

Async Version
Public Sub SendUrgentText(ByVal UrgentText As String) As Task
Public Sub SendUrgentText(ByVal UrgentText As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends the text specified by UrgentText as urgent data (out-of-band) to the remote host. To send binary data urgently use the SendUrgentBytes method instead.

Data sent using this method will bypass the normal TCP queuing mechanism. Use this method with caution.

SendWillOption Method (Telnet Component)

This method sends a single character Telnet option code the server with the Telnet WILL command.

Syntax

• C#
• VB.NET

public void SendWillOption(int willOption);

Async Version
public async Task SendWillOption(int willOption);
public async Task SendWillOption(int willOption, CancellationToken cancellationToken);

Public Sub SendWillOption(ByVal WillOption As Integer)

Async Version
Public Sub SendWillOption(ByVal WillOption As Integer) As Task
Public Sub SendWillOption(ByVal WillOption As Integer, cancellationToken As CancellationToken) As Task

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

SendWontOption Method (Telnet Component)

This method sends a single character Telnet option code to the server with the Telnet WONT command.

Syntax

• C#
• VB.NET

public void SendWontOption(int wontOption);

Async Version
public async Task SendWontOption(int wontOption);
public async Task SendWontOption(int wontOption, CancellationToken cancellationToken);

Public Sub SendWontOption(ByVal WontOption As Integer)

Async Version
Public Sub SendWontOption(ByVal WontOption As Integer) As Task
Public Sub SendWontOption(ByVal WontOption As Integer, cancellationToken As CancellationToken) As Task

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

Command Event (Telnet Component)

Fired when a Telnet command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnCommandHandler OnCommand;

public delegate void OnCommandHandler(object sender, TelnetCommandEventArgs e);

public class TelnetCommandEventArgs : EventArgs {
  public int CommandCode { get; }
}

Public Event OnCommand As OnCommandHandler

Public Delegate Sub OnCommandHandler(sender As Object, e As TelnetCommandEventArgs)

Public Class TelnetCommandEventArgs Inherits EventArgs
  Public ReadOnly Property CommandCode As Integer
End Class

Remarks

Codes for Telnet commands and their meanings are defined in the Telnet RFCs. Here are some examples:

Connected Event (Telnet Component)

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

Syntax

• C#
• VB.NET

public event OnConnectedHandler OnConnected;

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

public class TelnetConnectedEventArgs : EventArgs {
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnConnected As OnConnectedHandler

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

Public Class TelnetConnectedEventArgs Inherits EventArgs
  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 Transmission Control Protocol (TCP)/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Please refer to the Error Codes section for more information.

ConnectionStatus Event (Telnet Component)

This event is fired to indicate changes in the connection state.

Syntax

• C#
• VB.NET

public event OnConnectionStatusHandler OnConnectionStatus;

public delegate void OnConnectionStatusHandler(object sender, TelnetConnectionStatusEventArgs e);

public class TelnetConnectionStatusEventArgs : EventArgs {
  public string ConnectionEvent { get; }
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnConnectionStatus As OnConnectionStatusHandler

Public Delegate Sub OnConnectionStatusHandler(sender As Object, e As TelnetConnectionStatusEventArgs)

Public Class TelnetConnectionStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionEvent As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

The ConnectionStatus event is fired when the connection state changes: for example, completion of a firewall or proxy connection or completion of a security handshake.

The ConnectionEvent parameter indicates the type of connection event. Values may include the following:

DataIn Event (Telnet Component)

Fired when data is received from the remote host.

Syntax

• C#
• VB.NET

public event OnDataInHandler OnDataIn;

public delegate void OnDataInHandler(object sender, TelnetDataInEventArgs e);

public class TelnetDataInEventArgs : EventArgs {
  public string Text { get; }
  public byte[] TextB { get; }
}

Public Event OnDataIn As OnDataInHandler

Public Delegate Sub OnDataInHandler(sender As Object, e As TelnetDataInEventArgs)

Public Class TelnetDataInEventArgs Inherits EventArgs
  Public ReadOnly Property Text As String
  Public ReadOnly Property TextB As Byte()
End Class

Remarks

Trapping the DataIn event is your only chance to get the data coming from the other end of the connection. The incoming data is provided through the Text parameter.

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Disconnected Event (Telnet Component)

This event is fired when a connection is closed.

Syntax

• C#
• VB.NET

public event OnDisconnectedHandler OnDisconnected;

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

public class TelnetDisconnectedEventArgs : EventArgs {
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnDisconnected As OnDisconnectedHandler

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

Public Class TelnetDisconnectedEventArgs Inherits EventArgs
  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 Transmission Control Protocol (TCP/IP) subsystem. Description contains a description of this code. The value of StatusCode is equal to the value of the TCP/IP error.

Please refer to the Error Codes section for more information.

Do Event (Telnet Component)

Fired when a Telnet DO OPTION command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnDoHandler OnDo;

public delegate void OnDoHandler(object sender, TelnetDoEventArgs e);

public class TelnetDoEventArgs : EventArgs {
  public int OptionCode { get; }
}

Public Event OnDo As OnDoHandler

Public Delegate Sub OnDoHandler(sender As Object, e As TelnetDoEventArgs)

Public Class TelnetDoEventArgs Inherits EventArgs
  Public ReadOnly Property OptionCode As Integer
End Class

Remarks

The OptionCode parameter identifies the option code. For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

Dont Event (Telnet Component)

Fired when a Telnet DONT OPTION command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnDontHandler OnDont;

public delegate void OnDontHandler(object sender, TelnetDontEventArgs e);

public class TelnetDontEventArgs : EventArgs {
  public int OptionCode { get; }
}

Public Event OnDont As OnDontHandler

Public Delegate Sub OnDontHandler(sender As Object, e As TelnetDontEventArgs)

Public Class TelnetDontEventArgs Inherits EventArgs
  Public ReadOnly Property OptionCode As Integer
End Class

Remarks

The OptionCode parameter identifies the option code. For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

Error Event (Telnet Component)

Information about errors during data delivery.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

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

public class TelnetErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Public Event OnError As OnErrorHandler

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

Public Class TelnetErrorEventArgs Inherits EventArgs
  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.

ReadyToSend Event (Telnet Component)

Fired when the component is ready to send data.

Syntax

• C#
• VB.NET

public event OnReadyToSendHandler OnReadyToSend;

public delegate void OnReadyToSendHandler(object sender, TelnetReadyToSendEventArgs e);

public class TelnetReadyToSendEventArgs : EventArgs {
}

Public Event OnReadyToSend As OnReadyToSendHandler

Public Delegate Sub OnReadyToSendHandler(sender As Object, e As TelnetReadyToSendEventArgs)

Public Class TelnetReadyToSendEventArgs Inherits EventArgs
End Class

Remarks

The ReadyToSend event indicates that the underlying TCP/IP subsystem is ready to accept data after a failed DataToSend. The event is also fired immediately after a connection to the remote host is established.

SSLServerAuthentication Event (Telnet Component)

Fired after the server presents its certificate to the client.

Syntax

• C#
• VB.NET

public event OnSSLServerAuthenticationHandler OnSSLServerAuthentication;

public delegate void OnSSLServerAuthenticationHandler(object sender, TelnetSSLServerAuthenticationEventArgs e);

public class TelnetSSLServerAuthenticationEventArgs : EventArgs {
  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 OnSSLServerAuthentication As OnSSLServerAuthenticationHandler

Public Delegate Sub OnSSLServerAuthenticationHandler(sender As Object, e As TelnetSSLServerAuthenticationEventArgs)

Public Class TelnetSSLServerAuthenticationEventArgs Inherits EventArgs
  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 is where the client can decide whether to continue with the connection process or not. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether to continue or not.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK"). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

SSLStatus Event (Telnet Component)

Shows the progress of the secure connection.

Syntax

• C#
• VB.NET

public event OnSSLStatusHandler OnSSLStatus;

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

public class TelnetSSLStatusEventArgs : EventArgs {
  public string Message { get; }
}

Public Event OnSSLStatus As OnSSLStatusHandler

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

Public Class TelnetSSLStatusEventArgs Inherits EventArgs
  Public ReadOnly Property Message As String
End Class

Remarks

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

SubOption Event (Telnet Component)

Fired when a Telnet SubOption command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnSubOptionHandler OnSubOption;

public delegate void OnSubOptionHandler(object sender, TelnetSubOptionEventArgs e);

public class TelnetSubOptionEventArgs : EventArgs {
  public string SubOption { get; }
  public byte[] SubOptionB { get; }
}

Public Event OnSubOption As OnSubOptionHandler

Public Delegate Sub OnSubOptionHandler(sender As Object, e As TelnetSubOptionEventArgs)

Public Class TelnetSubOptionEventArgs Inherits EventArgs
  Public ReadOnly Property SubOption As String
  Public ReadOnly Property SubOptionB As Byte()
End Class

Remarks

The SubOption parameter contains the suboption data as sent by the other end. The enclosing suboption command codes are stripped away.

For a list of valid Telnet suboptions and their descriptions please look at the Telnet RFCs.

Will Event (Telnet Component)

Fired when a Telnet WILL OPTION command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnWillHandler OnWill;

public delegate void OnWillHandler(object sender, TelnetWillEventArgs e);

public class TelnetWillEventArgs : EventArgs {
  public int OptionCode { get; }
}

Public Event OnWill As OnWillHandler

Public Delegate Sub OnWillHandler(sender As Object, e As TelnetWillEventArgs)

Public Class TelnetWillEventArgs Inherits EventArgs
  Public ReadOnly Property OptionCode As Integer
End Class

Remarks

For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

Wont Event (Telnet Component)

Fired when a Telnet WONT OPTION command comes from the Telnet server.

Syntax

• C#
• VB.NET

public event OnWontHandler OnWont;

public delegate void OnWontHandler(object sender, TelnetWontEventArgs e);

public class TelnetWontEventArgs : EventArgs {
  public int OptionCode { get; }
}

Public Event OnWont As OnWontHandler

Public Delegate Sub OnWontHandler(sender As Object, e As TelnetWontEventArgs)

Public Class TelnetWontEventArgs Inherits EventArgs
  Public ReadOnly Property OptionCode As Integer
End Class

Remarks

The OptionCode parameter identifies the option code. For a list of option codes and their descriptions, please look at the Telnet RFCs. The following are a few examples:

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

• C#
• VB.NET

public Certificate();

Public Certificate()

Creates a Certificate instance whose properties can be set. This is useful for use with CERTMGR when generating new certificates.

• C#
• VB.NET

public Certificate(string certificateFile);

Public Certificate(ByVal CertificateFile As String)

Opens CertificateFile and reads out the contents as an X509 public key.

• C#
• VB.NET

public Certificate(byte[] certificateData);

Public Certificate(ByVal CertificateData As Byte())

Parses CertificateData as an X509 public key.

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, string store, string storePassword, string subject);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Subject As String)

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN).

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, string store, string storePassword, string subject, string configurationString);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Subject As String, ByVal ConfigurationString As String)

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. ConfigurationString is a newline separated list of name-value pairs that may be used to modify the default behavior. Possible values include "PersistPFXKey", which shows whether or not the PFX key is persisted after performing operations with the private key. This correlates to the PKCS12_NO_PERSIST_KEY CyrptoAPI option. The default value is True (the key is persisted). "Thumbprint" - a MD5, SHA1, or SHA256 thumbprint of the certificate to load. When specified, this value is used to select the certificate in the store. This is applicable to cstUser, cstMachine, cstPublicKeyFile, and cstPFXFile store types. "UseInternalSecurityAPI" shows whether the platform (default) or the internal security API is used when performing certificate-related operations. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN).

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, string store, string storePassword, byte[] encoded);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Encoded As Byte())

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will load Encoded as an X509 certificate and search the opened store for a corresponding private key.

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, byte[] storeBlob, string storePassword, string subject);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal StoreBlob As Byte(), ByVal StorePassword As String, ByVal Subject As String)

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. StoreBlob is a string (binary- or base64-encoded) containing the certificate data. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN).

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, byte[] storeBlob, string storePassword, string subject, string configurationString);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal StoreBlob As Byte(), ByVal StorePassword As String, ByVal Subject As String, ByVal ConfigurationString As String)

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. StoreBlob is a string (binary- or base64-encoded) containing the certificate data. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN).

• C#
• VB.NET

public Certificate(CertStoreTypes certStoreType, byte[] storeBlob, string storePassword, byte[] encoded);

Public Certificate(ByVal CertStoreType As CertStoreTypes, ByVal StoreBlob As Byte(), ByVal StorePassword As String, ByVal Encoded As Byte())

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a string (binary- or base64-encoded) containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will load Encoded as an X509 certificate and search the opened store for a corresponding private key.

Firewall Type

This is the firewall the component will connect through.

Remarks

When connecting through a firewall, this type is used to specify different properties of the firewall, such as the firewall Host and the FirewallType.

Fields

Constructors

• C#
• VB.NET

public Firewall();

Public Firewall()

Config Settings (Telnet Component)

TCPClient Config Settings

SSL Config Settings

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

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

Socket Config Settings

Base Config Settings

Trappable Errors (Telnet Component)

Telnet Errors

The component may also return one of the following error codes, which are inherited from other components.

SSLClient Errors

SSL Errors

TCP/IP Errors