SNMPTCPAgent Component

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The SNMPTCPAgent component is used to implement TCP-based SNMP Agent Applications.

Syntax

TipnSNMPTCPAgent

Remarks

The SNMPTCPAgent component implements a TCP-based standard SNMP Agent as specified in the SNMP RFCs. The component supports SNMP v1, v2c, and v3.

The component provides both encoding/decoding and transport capabilities, making the task of developing a custom SNMP agent as simple as setting a few key properties and handling a few events. SNMP data such as SNMP object id-s (OID-s) are exchanged as text strings, thus further simplifying the task of handling them.

The component is activated/deactivated by calling the Activate or Deactivate method. These methods enable or disable sending and receiving. The activation status can be found in the Active property.

The component operates asynchronously. Requests are received through events such as GetRequest, GetBulkRequest, GetNextRequest, etc. and the corresponding responses are automatically sent when the events return. Traps are sent through the SendTrap method.

SNMPv3 USM security passwords are requested through the GetUserPassword event, and event parameters such as User and SecurityLevel provide information about the security attributes of received requests, and enable granular decision capability about what to provide and what not to provide. The SendSecureTrap method is used to send authenticated (secure) SNMPv3 traps.

The AddUser, RemoveUser, ShowCache, and ClearCache methods are used to manage an internal authentication cache. This internal cache can be used as an alternative to the GetUserPassword event, automatically checking the cache against the security parameters provided in the request signature.

SNMP OIDs, types, and values are provided in the Objects collection of SNMP objects for both sent and received packets.

Other packet information is provided through corresponding event parameters, such as Community, or RequestId.

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 (SNMPTCPAgent Component)

Enables or disables data reception.

Syntax

property AcceptData: Boolean read get_AcceptData write set_AcceptData;

Default Value

true

Remarks

Setting the property to False temporarily disables data reception. Setting the property to True re-enables data reception.

This property is not available at design time.

Active Property (SNMPTCPAgent Component)

Indicates whether the component is active.

Syntax

property Active: Boolean read get_Active write set_Active;

Default Value

false

Remarks

This property indicates whether the component is currently active and can send or receive data.

The component will be automatically activated if it is not already and you attempt to perform an operation which requires the component to be active.

Use the Activate and Deactivate methods to control whether the component is active.

This property is not available at design time.

LocalEngineId Property (SNMPTCPAgent Component)

The Engine Id of the SNMP Agent.

Syntax

property LocalEngineId: String read get_LocalEngineId write set_LocalEngineId;
property LocalEngineIdB: TBytes read get_LocalEngineIdB write set_LocalEngineIdB;

Default Value

''

Remarks

This property is only used for SNMPv3 packets (when SNMPVersion is 3).

LocalHost Property (SNMPTCPAgent Component)

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

Syntax

property LocalHost: String read get_LocalHost write set_LocalHost;

Default Value

''

Remarks

This 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 multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the component initiate connections (or accept in the case of server components) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

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 multihomed 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 (SNMPTCPAgent Component)

The port in the local host where the component listens.

Syntax

property LocalPort: Integer read get_LocalPort write set_LocalPort;

Default Value

161

Remarks

The LocalPort property must be set before the component is activated (Active is set to True). It instructs the component to bind to a specific port (or communication endpoint) in the local machine (default 161).

You may also set LocalPort to 0. This allows the TCP/IP stack to choose a port at random. The value chosen is provided via the LocalPort property after the component is activated through the Active property.

LocalPort cannot be changed once the component is Active. Any attempt to set the LocalPort property when the component is Active will generate an error.

Note: on macOS and iOS, root permissions are required to set LocalPort to any value below 1024.

Objects Property (SNMPTCPAgent Component)

The objects in the current request.

Syntax

property Objects: TipnSNMPObjectList read get_Objects write set_Objects;

Remarks

The SNMP objects being sent or received in the current request. The collection is first cleared, then populated every time an SNMP packet is received. It is also used to create outgoing SNMP packets.

RequestId Property (SNMPTCPAgent Component)

The request-id to mark outgoing packets with.

Syntax

property RequestId: Integer read get_RequestId write set_RequestId;

Default Value

1

Remarks

If a custom value is needed for RequestId, the property must be set before sending the request. The component increments RequestId automatically after sending each packet.

This property is not available at design time.

SNMPVersion Property (SNMPTCPAgent Component)

Version of SNMP used for outgoing requests (traps).

Syntax

property SNMPVersion: TipnTSNMPVersions read get_SNMPVersion write set_SNMPVersion;

TipnTSNMPVersions = (
  snmpverV1,
  snmpverV2c,
  snmpverV3
);

Default Value

snmpverV2c

Remarks

This property takes one of the following values:

SSLAcceptServerCert Property (SNMPTCPAgent Component)

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

Syntax

property SSLAcceptServerCert: TipnCertificate read get_SSLAcceptServerCert write set_SSLAcceptServerCert;

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.

Note: This functionality is provided only for cases in which 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.

SSLAuthenticateClients Property (SNMPTCPAgent Component)

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

Syntax

property SSLAuthenticateClients: Boolean read get_SSLAuthenticateClients write set_SSLAuthenticateClients;

Default Value

false

Remarks

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

SSLCert Property (SNMPTCPAgent Component)

The certificate to be used during Secure Sockets Layer (SSL) negotiation.

Syntax

property SSLCert: TipnCertificate read get_SSLCert write set_SSLCert;

Remarks

This property includes 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.

SSLEnabled Property (SNMPTCPAgent Component)

Whether TLS/SSL is enabled.

Syntax

property SSLEnabled: Boolean read get_SSLEnabled write set_SSLEnabled;

Default Value

false

Remarks

This setting specifies whether TLS/SSL is enabled in the component. When False (default) the component operates in plaintext mode. When True TLS/SSL is enabled.

This property is not available at design time.

SSLServerCert Property (SNMPTCPAgent Component)

The server certificate for the last established connection.

Syntax

property SSLServerCert: TipnCertificate read get_SSLServerCert;

Remarks

This property contains the server certificate for the last established connection.

SSLServerCert is reset every time a new connection is attempted.

This property is read-only.

SysUpTime Property (SNMPTCPAgent Component)

Time passed since the agent was initialized (in hundredths of a second).

Syntax

property SysUpTime: Int64 read get_SysUpTime write set_SysUpTime;

Default Value

0

Remarks

This property is used when sending SNMP traps, and it normally provides the time since the system was restarted in 1/100s of a second.

If another value is desired, you may set this property to a custom value. From that point on, SysUpTime will return the value set plus time elapsed.

This property is not available at design time.

Activate Method (SNMPTCPAgent Component)

Activates the component.

Syntax

procedure Activate();

Remarks

This method activates the component and will allow it to send or receive data.

The component will be automatically activated if it is not already and you attempt to perform an operation which requires the component to be active.

Note: Use the Active property to check whether the component is active.

AddUser Method (SNMPTCPAgent Component)

Adds a user to the internal authentication cache.

Syntax

procedure AddUser(User: String; AuthenticationProtocol: Integer; AuthenticationPassword: String; EncryptionAlgorithm: Integer; EncryptionPassword: String);

Remarks

The internal authentication cache can be used as an alternative to the GetUserPassword event, automatically checking the cache against the security parameters provided in the request signature.

The ShowCache method is used to show the contents of the internal authentication cache.

The ClearCache method can be used to completely clear the cache.

Valid Authentication Protocols are:

Valid Encryption Algorithms are:

NOTE: Specifying an authentication protocol of 0 is a special case where the component will attempt to verify users with all valid authentication protocols.

ClearCache Method (SNMPTCPAgent Component)

Clears the internal authentication database.

Syntax

procedure ClearCache();

Remarks

All user records are removed from the internal authentication cache as a result of this call.

Config Method (SNMPTCPAgent Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): 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.

Deactivate Method (SNMPTCPAgent Component)

Deactivates the component.

Syntax

procedure Deactivate();

Remarks

This method deactivates the component and will prohibit it from sending and receiving data.

Note: Use the Active property to check whether the component is active.

DoEvents Method (SNMPTCPAgent Component)

This method processes events from the internal message queue.

Syntax

procedure DoEvents();

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.

HashPasswords Method (SNMPTCPAgent Component)

Hashes all passwords in the cache.

Syntax

procedure HashPasswords();

Remarks

Forces computation of all passwords hashes in the cache. Used together with the HashPassword event to enable implementations of external password hash storage.

RemoveUser Method (SNMPTCPAgent Component)

Removes the user specified by User from the internal authentication cache.

Syntax

procedure RemoveUser(User: String);

Remarks

The internal authentication cache can be used as an alternative to the GetUserPassword event, automatically checking the cache against the security parameters provided in the request signature.

The ShowCache method is used to show the contents of the internal authentication cache.

The ClearCache method can be used to completely clear the cache.

Reset Method (SNMPTCPAgent Component)

Clears the object arrays.

Syntax

procedure Reset();

Remarks

Clears the object arrays, and sets the trap and error properties to their default values. This is useful for reinitializing all the properties that are used to create outgoing packets before building a new packet.

Note: SNMPVersion will be reset to snmpverV2c (2).

SendResponse Method (SNMPTCPAgent Component)

Sends a response packet to a Get, Get-Next, Get-Bulk, or Set request.

Syntax

procedure SendResponse(RemoteHost: String; RemotePort: Integer; RequestId: Integer; Community: String; ErrorStatus: Integer; ErrorIndex: Integer);

Remarks

Use this method to send asynchronous response packets. A valid RequestId must be specified. SendResponse sends an unauthenticated response packet. Depending upon the value of the SNMPVersion property, the packet is constructed as an SNMPv1, SNMPv2c, or SNMPv3 (unauthenticated) response PDU. To send authenticated or encrypted SNMPv3 responses, use SendSecureResponse

The RemoteHost and RemotePort parameters are used to determine where the response is to be sent. The object identifiers, types, and values for the request are taken from the Objects collection. The RequestId, Community, ErrorStatus, and ErrorIndex parameters are used to specify other properties of the response.

SendSecureResponse Method (SNMPTCPAgent Component)

Sends an authenticated and/or encrypted SNMPv3 response.

Syntax

procedure SendSecureResponse(RemoteHost: String; RemotePort: Integer; RequestId: Integer; MessageId: Integer; ErrorStatus: Integer; ErrorIndex: Integer; User: String; AuthenticationProtocol: Integer; AuthenticationPassword: String; EncryptionAlgorithm: Integer; EncryptionPassword: String);

Remarks

Similar to the SendResponse method except that User, Authentication Protocol, and AuthenticationPassword are used to authenticate the response. EncryptionAlgorithm and EncryptionPassword (if not empty) are used to encrypt the response.

The MessageId argument must match the MessageId parameter obtained from the GetRequest, GetNextRequest, SetRequest, or GetBulkRequest event.

The user and password arguments used to send the response will be added to the internal user cache. If the user is already in the cache, its passwords will be updated with those supplied.

Valid Authentication Protocols are:

Valid Encryption Algorithms are:

SendSecureTrap Method (SNMPTCPAgent Component)

Sends an authenticated and/or encrypted SNMPv3 trap.

Syntax

procedure SendSecureTrap(RemoteHost: String; TrapOID: String; User: String; AuthenticationProtocol: Integer; AuthenticationPassword: String; EncryptionAlgorithm: Integer; EncryptionPassword: String);

Remarks

Similar to the SendTrap method except that User, AuthenticationPassword, and Authentication Protocol are used to authenticate the trap. EncryptionPassword (if not empty) and EncryptionAlgorithm are used to encrypt the message.

The user and password arguments used to send the trap will be added to the internal user cache. If the user is already in the cache, its passwords will be updated with those supplied.

Valid Authentication Protocols are:

Valid Encryption Algorithms are:

SendTrap Method (SNMPTCPAgent Component)

Sends an SNMP Trap.

Syntax

procedure SendTrap(RemoteHost: String; TrapOID: String);

Remarks

Depending upon the value of the SNMPVersion property, the packet is constructed as an SNMPv1 or SNMPv2 Trap PDU. The following configuration settings provide more control about how traps are generated: TrapPort, TrapAgentAddress, TrapCommunity, TrapEnterprise. The SysUpTime property provides the trap timestamp.

SendTrap sends an unauthenticated trap. The SendSecureTrap method is used to send authenticated SNMPv3 traps.

If any values are provided in the Objects collection, they are sent unchanged. In the case of an SNMPv2 or SNMPv3 Trap, if Objects has a count that is equal to 0, the following values are set: sysUpTime.0 equal to SysUpTime and snmpTrapOID.0 equal to TrapOID.

For SNMPv2 and SNMPv3 Traps, TrapOID must contain the full OID of the Trap. For SNMPv1, TrapOID must be a string of the form "generic.specific" where generic and specific are numeric values providing the Trap Generic Type and Specific Type.

For SNMPv1, TrapOID must be of the form "GenericTrap.SpecificTrap". These values are sent in the PDU header. TrapAgentAddress and TrapEnterprise are taken from the corresponding configuration settings.

Additionally, the following symbolic values are recognized and translated as follows:

ShowCache Method (SNMPTCPAgent Component)

Lists all entries in the internal user authentication cache.

Syntax

procedure ShowCache();

Remarks

A CacheEntry event is fired for every record in the internal user authentication cache.

The internal authentication cache can be used as an alternative to the GetUserPassword event, automatically checking the cache against the security parameters provided in the request signature.

The ShowCache method is used to show the contents of the internal authentication cache.

The ClearCache method can be used to completely clear the cache.

Value Method (SNMPTCPAgent Component)

Returns the value corresponding to an OID.

Syntax

function Value(OID: String): String;

Remarks

If the OID does not exist in the Objects collection, a trappable error is generated.

Please refer to the SNMPObject type for more information.

BadPacket Event (SNMPTCPAgent Component)

Fired for erroneous and/or malformed messages.

Syntax

type TBadPacketEvent = procedure (
  Sender: TObject;
  const Packet: String;
  const PacketB: TBytes;
  const SourceAddress: String;
  SourcePort: Integer;
  ErrorCode: Integer;
  const ErrorDescription: String;
  var Report: Boolean
) of Object;

property OnBadPacket: TBadPacketEvent read FOnBadPacket write FOnBadPacket;

Remarks

The full message is provided in the Packet parameter.

The BadPacket event is also fired when authentication fails for received packets due to a bad password or other reasons.

If the Report parameter is set to True, an unauthenticated error report will be sent to the client, otherwise the packet will be silently ignored.

Please refer to the GetUserPassword event for more information concerning SNMPv3 authentication.

CacheEntry Event (SNMPTCPAgent Component)

Shows in the internal cache.

Syntax

type TCacheEntryEvent = procedure (
  Sender: TObject;
  const User: String;
  const AuthenticationProtocol: String;
  const AuthenticationPassword: String;
  const EncryptionAlgorithm: String;
  const EncryptionPassword: String
) of Object;

property OnCacheEntry: TCacheEntryEvent read FOnCacheEntry write FOnCacheEntry;

Remarks

CacheEntry events are triggered by a call to ShowCache. One event is fired for each user.

Connected Event (SNMPTCPAgent Component)

Fired immediately after a connection completes (or fails).

Syntax

type TConnectedEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

Remarks

This event fires after a connection completes or fails.

StatusCode is the value returned by the system TCP/IP stack. This will be 0 if the connection was successful.

Description contains a human readable description of the status. This will be "OK" if the connection was successful.

RemoteAddress is the IP address of the remote host.

RemotePort is the port on the remote host.

ConnectionStatus Event (SNMPTCPAgent Component)

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

Syntax

type TConnectionStatusEvent = procedure (
  Sender: TObject;
  const ConnectionEvent: String;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnectionStatus: TConnectionStatusEvent read FOnConnectionStatus write FOnConnectionStatus;

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:

Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Disconnected Event (SNMPTCPAgent Component)

Fired when a connection is closed.

Syntax

type TDisconnectedEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

Remarks

This event fires after a connection is broken.

StatusCode is the value returned by the system TCP/IP stack. This will be 0 if the connection was broken normally.

Description contains a human readable description of the status. This will be "OK" if the connection was broken normally.

RemoteAddress is the IP address of the remote host.

RemotePort is the port on the remote host.

DiscoveryRequest Event (SNMPTCPAgent Component)

Fired when an SNMPv3 discovery packet is received.

Syntax

type TDiscoveryRequestEvent = procedure (
  Sender: TObject;
  const EngineId: String;
  const EngineIdB: TBytes;
  EngineBoots: Integer;
  EngineTime: Integer;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  var Respond: Boolean
) of Object;

property OnDiscoveryRequest: TDiscoveryRequestEvent read FOnDiscoveryRequest write FOnDiscoveryRequest;

Remarks

EngineId, EngineBoots, EngineTime, and User are the values received from SourceAddress.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

Respond is True by default, and will automatically send a response using the value in LocalEngineId. To suppress the response, set Respond to False.

The value returned to SourceAddress for EngineBoots is always 0, and EngineTime is the number of seconds since January 1st, 1970 (GMT).

Error Event (SNMPTCPAgent Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

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

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

GetBulkRequest Event (SNMPTCPAgent Component)

Fired when a GetBulkRequest packet is received.

Syntax

type TGetBulkRequestEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  MessageId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  NonRepeaters: Integer;
  MaxRepetitions: Integer;
  var ErrorIndex: Integer;
  var ErrorStatus: Integer;
  const ErrorDescription: String;
  var Respond: Boolean
) of Object;

property OnGetBulkRequest: TGetBulkRequestEvent read FOnGetBulkRequest write FOnGetBulkRequest;

Remarks

This is only available for SNMP versions 2 and 3.

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

The MessageId parameter identifies the received request.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

To send a response, the Respond parameter must be set to true. By default, this value is false, which means no response will be sent. The ErrorStatus parameter may also be set to a valid SNMP status code (the default value is 0, which represents no error).

The following is a list of valid SNMP status code values:

Variable indexes start with 0. ErrorIndex has no meaning when ErrorStatus is 0 (no error).

A GetBulkRequest is very similar to a GetNextRequest, the difference is that Getbulk performs a continuous GetNext operation based on the MaxRepitions value. The NonRepeaters value will determine the number of Objects for which a simple GetNext operation should be performed. For the remaining variables, a continuous GetNext operation is performed based on the MaxRepitions value.

So if you send a request containing X objects, the agent will perform N simple GetNext operations and M continuous GetNext operations X - N times. With X being the number of objects received, N being the number of NonRepeaters, and M being the number of MaxRepitions. Thus the SNMPMgr is expecting to receive N + M x (X - N) objects, assuming that each object has M successors.

GetNextRequest Event (SNMPTCPAgent Component)

Fired when a GetNextRequest packet is received.

Syntax

type TGetNextRequestEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  MessageId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  var ErrorIndex: Integer;
  var ErrorStatus: Integer;
  const ErrorDescription: String;
  var Respond: Boolean
) of Object;

property OnGetNextRequest: TGetNextRequestEvent read FOnGetNextRequest write FOnGetNextRequest;

Remarks

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

The MessageId parameter identifies the received request.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

To send a response, the Respond parameter must be set to true. By default, this value is false, which means no response will be sent. The ErrorStatus parameter may also be set to a valid SNMP status code (the default value is 0, which represents no error).

The following is a list of valid SNMP status code values:

Variable indexes start with 0. ErrorIndex has no meaning when ErrorStatus is 0 (no error).

GetRequest Event (SNMPTCPAgent Component)

Fired when a GetRequest packet is received.

Syntax

type TGetRequestEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  MessageId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  var ErrorIndex: Integer;
  var ErrorStatus: Integer;
  const ErrorDescription: String;
  var Respond: Boolean
) of Object;

property OnGetRequest: TGetRequestEvent read FOnGetRequest write FOnGetRequest;

Remarks

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

The MessageId parameter identifies the received request.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

To send a response, the Respond parameter must be set to true. By default, this value is false, which means no response will be sent. The ErrorStatus parameter may also be set to a valid SNMP status code (the default value is 0, which represents no error).

The following is a list of valid SNMP status code values:

Variable indexes start with 0. ErrorIndex has no meaning when ErrorStatus is 0 (no error).

GetUserPassword Event (SNMPTCPAgent Component)

Retrieves a password associated with a user.

Syntax

type TGetUserPasswordEvent = procedure (
  Sender: TObject;
  PasswordType: Integer;
  const User: String;
  var Password: String;
  var Algorithm: Integer
) of Object;

property OnGetUserPassword: TGetUserPasswordEvent read FOnGetUserPassword write FOnGetUserPassword;

Remarks

The GetUserPassword event is fired after initial inspection of SNMPv3 requests.

The type of password required is provided in the PasswordType parameter: 1 for authentication, and 2 for encryption (privacy).

The password corresponding to User (if any) must be provided in the Password parameter. If the password is valid, processing will continue to other events such as GetRequest, SetRequest, etc.

If the PasswordType parameter is 1 (authentication is used), the Algorithm parameter can be set. Possible values are:

If the password does not match the signature in the request, a BadPacket event will be fired, at which point you can decide whether to report the error to the client (see the description of the BadPacket event for more information).

If the User is invalid or unknown, set the password to empty string (default) to ignore the request. This will result in a BadPacket event being fired, at which point you can decide whether to report the error to the client or not.

GetUserSecurityLevel Event (SNMPTCPAgent Component)

Sets the security level for an incoming packet.

Syntax

type TGetUserSecurityLevelEvent = procedure (
  Sender: TObject;
  const User: String;
  const EngineId: String;
  const EngineIdB: TBytes;
  var SecurityLevel: Integer
) of Object;

property OnGetUserSecurityLevel: TGetUserSecurityLevelEvent read FOnGetUserSecurityLevel write FOnGetUserSecurityLevel;

Remarks

The GetUserSecurityLevel event is fired after the first inspection of each SNMPv3 request. The SecurityLevel parameter determines the level of security for the message.

On entry, the SecurityLevel parameter contains the default security level for User if the user is located in the internal cache, or if the User is not found in the cache, the SecurityLevel will be -1.

The value of SecurityLevel upon exiting the event, determines how the message will be processed:

HashPassword Event (SNMPTCPAgent Component)

Fired before and after a password is hashed.

Syntax

type THashPasswordEvent = procedure (
  Sender: TObject;
  const Password: String;
  AuthAlgorithm: Integer;
  var Hash: String
) of Object;

property OnHashPassword: THashPasswordEvent read FOnHashPassword write FOnHashPassword;

Remarks

SNMPv3 passwords are hashed in order to obtain authentication and encryption keys. This is an expensive operation, and in certain situations it may be preferable to store the hashed passwords externally and supply them on demand.

If a hash is required, the event fires with an empty string in the Hash parameter. In this case, you can choose to supply a value for the hash and stop the component from computing the hash.

The event also fires every time a hash is computed. In this case, the Hash parameter contains the value of the computed hash.

AuthAlgorithm contains either 1 for HMAC-MD5-96, 2 for HMAC-SHA-96 or 3 for HMAC-192-SHA-256

PacketTrace Event (SNMPTCPAgent Component)

Fired for every packet sent or received.

Syntax

type TPacketTraceEvent = procedure (
  Sender: TObject;
  const Packet: String;
  const PacketB: TBytes;
  Direction: Integer;
  const PacketAddress: String;
  PacketPort: Integer
) of Object;

property OnPacketTrace: TPacketTraceEvent read FOnPacketTrace write FOnPacketTrace;

Remarks

The PacketTrace event shows all the packets sent or received by the component.

Packet contains the full contents of the datagram.

Direction shows the direction of the packet: 1 for incoming packets, and 2 for outgoing packets.

In the case of an incoming packet, PacketAddress and PacketPort identify the source of the packet.

In the case of an outgoing packet, PacketAddress and PacketPort identify the destination of the packet.

ReadyToSend Event (SNMPTCPAgent Component)

Fired when the component is ready to send data.

Syntax

type TReadyToSendEvent = procedure (
  Sender: TObject
) of Object;

property OnReadyToSend: TReadyToSendEvent read FOnReadyToSend write FOnReadyToSend;

Remarks

The ReadyToSend event indicates that the underlying TCP/IP subsystem is ready to accept data after a failed DataToSend(TBD. DataToSend is removed).

Report Event (SNMPTCPAgent Component)

Fired when a Report packet is received.

Syntax

type TReportEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  ErrorIndex: Integer;
  ErrorStatus: Integer;
  const ErrorDescription: String
) of Object;

property OnReport: TReportEvent read FOnReport write FOnReport;

Remarks

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

SetRequest Event (SNMPTCPAgent Component)

Fired when a SetRequest packet is received.

Syntax

type TSetRequestEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  MessageId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  var ErrorIndex: Integer;
  var ErrorStatus: Integer;
  const ErrorDescription: String;
  var Respond: Boolean
) of Object;

property OnSetRequest: TSetRequestEvent read FOnSetRequest write FOnSetRequest;

Remarks

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

The MessageId parameter identifies the received request.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

To send a response, the Respond parameter must be set to true. By default, this value is false, which means no response will be sent. The ErrorStatus parameter may also be set to a valid SNMP status code (the default value is 0, which represents no error).

The following is a list of valid SNMP status code values:

Variable indexes start with 0. ErrorIndex has no meaning when ErrorStatus is 0 (no error).

SSLClientAuthentication Event (SNMPTCPAgent Component)

Fired when the client presents its credentials to the server.

Syntax

type TSSLClientAuthenticationEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const CertEncoded: String;
  const CertEncodedB: TBytes;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSLClientAuthentication: TSSLClientAuthenticationEvent read FOnSSLClientAuthentication write FOnSSLClientAuthentication;

Remarks

This event fires when a client connects to the component and presents a certificate for authentication. 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").

RemoteAddress is the IP address of the connecting client.

RemotePort is the source port of the connecting client.

CertEncoded is the base64 encoded certificate presented by the client.

CertSubject is the subject of the certificate presented by the client.

CertIssuer is the subject of the issuer of the certificate presented by the client.

Status is the stauts of the certificate.

Accept defines whether the certificate is accepted.

SSLServerAuthentication Event (SNMPTCPAgent Component)

Fires when connecting to the server.

Syntax

type TSSLServerAuthenticationEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const CertEncoded: String;
  const CertEncodedB: TBytes;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSLServerAuthentication: TSSLServerAuthenticationEvent read FOnSSLServerAuthentication write FOnSSLServerAuthentication;

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.

RemoteAddress is the IP address of the server.

RemotePort is the source port of the server.

CertEncoded is the base64 encoded certificate presented by the server.

CertSubject is the subject of the certificate presented by the server.

CertIssuer is the subject of the issuer of the certificate presented by the server.

Status is the stauts of the certificate.

Accept defines whether the certificate is accepted.

SSLStatus Event (SNMPTCPAgent Component)

Shows the progress of the secure connection.

Syntax

type TSSLStatusEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const Message: String
) of Object;

property OnSSLStatus: TSSLStatusEvent read FOnSSLStatus write FOnSSLStatus;

Remarks

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

RemoteAddress is the IP address of the remote machine.

RemotePort is the port of the remote machine.

Message is the log message.

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

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constructor Create();

constructor Create(valEncoded: TBytes);

constructor Create(valStoreType: TipnCertStoreTypes; valStore: String; valStorePassword: String; valSubject: String);

constructor Create(valStoreType: TipnCertStoreTypes; valStore: TBytes; valStorePassword: String; valSubject: String);

SNMPObject Type

The current SNMP object.

Remarks

This type defines an SNMP object. Each object has an Oid, ObjectType, and Value. These values are populated by the component when incoming packets are received. You may use these fields to define objects to be used in outgoing packets.

Fields

Constructors

constructor Create();

constructor Create(valOid: String);

constructor Create(valOid: String; valValue: TBytes);

Config Settings (SNMPTCPAgent Component)

SNMPTCPAgent Config Settings

TCPClient Config Settings

SSL Config Settings

-----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-----

-----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-----

-----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-----

Socket Config Settings

Base Config Settings

Trappable Errors (SNMPTCPAgent Component)

SNMPTCPAgent Errors

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

TCPClient Errors

SSL Errors

TCP/IP Errors