SNMPAgent Control

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The SNMPAgent control is used to implement UDP-based SNMP Agent Applications.

Syntax

SNMPAgent

Remarks

The SNMPAgent control implements a UDP-based standard SNMP Agent as specified in the SNMP RFCs. The control supports SNMP v1, v2c, and v3.

The control 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 control 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 control 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

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

Method List

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

Event List

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

Config Settings

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

AcceptData Property (SNMPAgent Control)

Enables or disables data reception.

Syntax

snmpagentcontrol.AcceptData[=boolean]

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.

Data Type

Boolean

Active Property (SNMPAgent Control)

Indicates whether the control is active.

Syntax

snmpagentcontrol.Active[=boolean]

Default Value

False

Remarks

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

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

Note: Use the Activate or Deactivate method to control whether the control is active.

This property is not available at design time.

Data Type

Boolean

LocalEngineId Property (SNMPAgent Control)

The Engine Id of the SNMP Agent.

Syntax

snmpagentcontrol.LocalEngineId[=string]

Default Value

""

Remarks

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

To read or write binary data to the property, a Variant (Byte Array) version is provided in .LocalEngineIdB.

Data Type

Binary String

LocalHost Property (SNMPAgent Control)

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

Syntax

snmpagentcontrol.LocalHost[=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 control initiate connections (or accept in the case of server controls) only through that interface.

If the control 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.

Data Type

String

LocalPort Property (SNMPAgent Control)

The port in the local host where the control listens.

Syntax

snmpagentcontrol.LocalPort[=integer]

Default Value

161

Remarks

The LocalPort property must be set before the control is activated (Active is set to True). It instructs the control 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 control is activated through the Active property.

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

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

Data Type

Integer

ObjCount Property (SNMPAgent Control)

The number of records in the Obj arrays.

Syntax

snmpagentcontrol.ObjCount[=integer]

Default Value

0

Remarks

This property controls the size of the following arrays:

• ObjId
• ObjType
• ObjTypeString
• ObjValue

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

This property is not available at design time.

Data Type

Integer

ObjType Property (SNMPAgent Control)

The current object's type.

Syntax

snmpagentcontrol.ObjType(ObjIndex)[=integer]

Possible Values

otInteger(2), 
otOctetString(4), 
otNull(5), 
otObjectId(6), 
otIPAddress(64), 
otCounter32(65), 
otGauge32(66), 
otTimeTicks(67), 
otOpaque(68), 
otNSAP(69), 
otCounter64(70), 
otUnsignedInteger32(71), 
otNoSuchObject(128), 
otNoSuchInstance(129), 
otEndOfMibView(130)

Default Value

5

Remarks

The current object's type. The default type is NULL (5).

The corresponding object id and value are specified by the ObjOid and ObjValue properties.

Possible object type values include:

The control also supports the following artificial object values used to designate error conditions:

The ObjIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ObjCount property.

This property is not available at design time.

Data Type

Integer

ObjId Property (SNMPAgent Control)

The current object's id which is encoded as a string of numbers separated by periods.

Syntax

snmpagentcontrol.ObjId(ObjIndex)[=string]

Default Value

""

Remarks

The current object's id which is encoded as a string of numbers separated by periods. For instance: "1.3.6.1.2.1.1.1.0" (OID for "system description").

The corresponding object type and value (if any) are specified by the ObjectType and ObjValue properties.

Example

SNMPControl.ObjCount = 1 SNMPControl.ObjId(0) = "1.3.6.1.2.1.1.1.0"

The ObjIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ObjCount property.

This property is not available at design time.

Data Type

String

ObjTypeString Property (SNMPAgent Control)

A string representation of the current object's ObjectType .

Syntax

snmpagentcontrol.ObjTypeString(ObjIndex)

Default Value

""

Remarks

A string representation of the current object's ObjectType.

The corresponding object id and value are specified by the ObjOid and ObjValue properties.

The ObjIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ObjCount property.

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

Data Type

String

ObjValue Property (SNMPAgent Control)

The current object's value.

Syntax

snmpagentcontrol.ObjValue(ObjIndex)[=string]

Default Value

""

Remarks

The current object's value. The corresponding object id and type are specified by the ObjOid and ObjectType properties.

Example

SNMPControl.ObjCount = 1 SNMPControl.ObjId(0) = "1.3.6.1.2.1.1.1.0" SNMPControl.ObjValue(0) = "New Value"

The ObjIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ObjCount property.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .ObjValueB.

This property is not available at design time.

Data Type

Binary String

RequestId Property (SNMPAgent Control)

The request-id to mark outgoing packets with.

Syntax

snmpagentcontrol.RequestId[=integer]

Default Value

1

Remarks

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

This property is not available at design time.

Data Type

Integer

SNMPVersion Property (SNMPAgent Control)

Version of SNMP used for outgoing requests (traps).

Syntax

snmpagentcontrol.SNMPVersion[=integer]

Possible Values

snmpverV1(1), 
snmpverV2c(2), 
snmpverV3(3)

Default Value

2

Remarks

This property takes one of the following values:

Data Type

Integer

SysUpTime Property (SNMPAgent Control)

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

Syntax

snmpagentcontrol.SysUpTime[=long64]

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.

Data Type

Long64

Activate Method (SNMPAgent Control)

Activates the control.

Syntax

snmpagentcontrol.Activate 

Remarks

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

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

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

AddUser Method (SNMPAgent Control)

Adds a user to the internal authentication cache.

Syntax

snmpagentcontrol.AddUser User, AuthenticationProtocol, AuthenticationPassword, EncryptionAlgorithm, EncryptionPassword

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 control will attempt to verify users with all valid authentication protocols.

ClearCache Method (SNMPAgent Control)

Clears the internal authentication database.

Syntax

snmpagentcontrol.ClearCache 

Remarks

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

Config Method (SNMPAgent Control)

Sets or retrieves a configuration setting.

Syntax

snmpagentcontrol.Config ConfigurationString

Remarks

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

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

Deactivates the control.

Syntax

snmpagentcontrol.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 (SNMPAgent Control)

Processes events from the internal message queue.

Syntax

snmpagentcontrol.DoEvents 

Remarks

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

HashPasswords Method (SNMPAgent Control)

Hashes all passwords in the cache.

Syntax

snmpagentcontrol.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 (SNMPAgent Control)

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

Syntax

snmpagentcontrol.RemoveUser User

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 (SNMPAgent Control)

Clears the object arrays.

Syntax

snmpagentcontrol.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 (SNMPAgent Control)

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

Syntax

snmpagentcontrol.SendResponse RemoteHost, RemotePort, RequestId, Community, ErrorStatus, ErrorIndex

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 (SNMPAgent Control)

Sends an authenticated and/or encrypted SNMPv3 response.

Syntax

snmpagentcontrol.SendSecureResponse RemoteHost, RemotePort, RequestId, MessageId, ErrorStatus, ErrorIndex, User, AuthenticationProtocol, AuthenticationPassword, EncryptionAlgorithm, EncryptionPassword

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 (SNMPAgent Control)

Sends an authenticated and/or encrypted SNMPv3 trap.

Syntax

snmpagentcontrol.SendSecureTrap RemoteHost, TrapOID, User, AuthenticationProtocol, AuthenticationPassword, EncryptionAlgorithm, EncryptionPassword

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 (SNMPAgent Control)

Sends an SNMP Trap.

Syntax

snmpagentcontrol.SendTrap RemoteHost, TrapOID

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 (SNMPAgent Control)

Lists all entries in the internal user authentication cache.

Syntax

snmpagentcontrol.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 (SNMPAgent Control)

Returns the value corresponding to an OID.

Syntax

snmpagentcontrol.Value OID

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 (SNMPAgent Control)

Fired for erroneous and/or malformed messages.

Syntax

Sub snmpagentcontrol_BadPacket(Packet As String, SourceAddress As String, SourcePort As Integer, ErrorCode As Integer, ErrorDescription As String, Report As Boolean)

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 (SNMPAgent Control)

Shows in the internal cache.

Syntax

Sub snmpagentcontrol_CacheEntry(User As String, AuthenticationProtocol As String, AuthenticationPassword As String, EncryptionAlgorithm As String, EncryptionPassword As String)

Remarks

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

DiscoveryRequest Event (SNMPAgent Control)

Fired when an SNMPv3 discovery packet is received.

Syntax

Sub snmpagentcontrol_DiscoveryRequest(EngineId As String, EngineBoots As Integer, EngineTime As Integer, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, Respond As Boolean)

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 (SNMPAgent Control)

Fired when information is available about errors during data delivery.

Syntax

Sub snmpagentcontrol_Error(ErrorCode As Integer, Description As String)

Remarks

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

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 (SNMPAgent Control)

Fired when a GetBulkRequest packet is received.

Syntax

Sub snmpagentcontrol_GetBulkRequest(RequestId As Integer, MessageId As Integer, SNMPVersion As Integer, Community As String, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, NonRepeaters As Integer, MaxRepetitions As Integer, ErrorIndex As Integer, ErrorStatus As Integer, ErrorDescription As String, Respond As Boolean)

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 ObjId, ObjType, and ObjValue 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:

The ErrorIndex parameter indicates the index of the first variable (object) that caused an error. The default value is 0.

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 (SNMPAgent Control)

Fired when a GetNextRequest packet is received.

Syntax

Sub snmpagentcontrol_GetNextRequest(RequestId As Integer, MessageId As Integer, SNMPVersion As Integer, Community As String, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, ErrorIndex As Integer, ErrorStatus As Integer, ErrorDescription As String, Respond As Boolean)

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 ObjId, ObjType, and ObjValue 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:

The ErrorIndex parameter indicates the index of the first variable (object) that caused an error. The default value is 0.

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

GetRequest Event (SNMPAgent Control)

Fired when a GetRequest packet is received.

Syntax

Sub snmpagentcontrol_GetRequest(RequestId As Integer, MessageId As Integer, SNMPVersion As Integer, Community As String, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, ErrorIndex As Integer, ErrorStatus As Integer, ErrorDescription As String, Respond As Boolean)

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 ObjId, ObjType, and ObjValue 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:

The ErrorIndex parameter indicates the index of the first variable (object) that caused an error. The default value is 0.

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

GetUserPassword Event (SNMPAgent Control)

Retrieves a password associated with a user.

Syntax

Sub snmpagentcontrol_GetUserPassword(PasswordType As Integer, User As String, Password As String, Algorithm As Integer)

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 PasswordType parameter is 2 (encryption is used), the Algorithm parameter must also 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 (SNMPAgent Control)

Sets the security level for an incoming packet.

Syntax

Sub snmpagentcontrol_GetUserSecurityLevel(User As String, EngineId As String, SecurityLevel As Integer)

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 (SNMPAgent Control)

Fired before and after a password is hashed.

Syntax

Sub snmpagentcontrol_HashPassword(Password As String, AuthAlgorithm As Integer, Hash As String)

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 control 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 (SNMPAgent Control)

Fired for every packet sent or received.

Syntax

Sub snmpagentcontrol_PacketTrace(Packet As String, Direction As Integer, PacketAddress As String, PacketPort As Integer)

Remarks

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

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 (SNMPAgent Control)

Fired when the control is ready to send data.

Syntax

Sub snmpagentcontrol_ReadyToSend()

Remarks

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

Report Event (SNMPAgent Control)

Fired when a Report packet is received.

Syntax

Sub snmpagentcontrol_Report(RequestId As Integer, SNMPVersion As Integer, Community As String, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, ErrorIndex As Integer, ErrorStatus As Integer, ErrorDescription As String)

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 ObjId, ObjType, and ObjValue 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 (SNMPAgent Control)

Fired when a SetRequest packet is received.

Syntax

Sub snmpagentcontrol_SetRequest(RequestId As Integer, MessageId As Integer, SNMPVersion As Integer, Community As String, User As String, SecurityLevel As Integer, SourceAddress As String, SourcePort As Integer, ErrorIndex As Integer, ErrorStatus As Integer, ErrorDescription As String, Respond As Boolean)

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 ObjId, ObjType, and ObjValue 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:

The ErrorIndex parameter indicates the index of the first variable (object) that caused an error. The default value is 0.

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

Config Settings (SNMPAgent Control)

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

SNMPAgent Config Settings

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (SNMPAgent Control)

SNMPAgent Errors

	20202    Timeout.
	20302    Bad Object Index.
	20303    Value exceeds maximum number of objects allowed.
	20304    The value must be an IP address in dotted format.
	20306    Unsupported SNMP version.
	20307    Unknown PDU type.
	20308    The control is busy performing the current action.
	20309    Verification failed.
	20310    Missing password for Verification.
	20311    Missing signature.
	20312    Missing remote time.
	20313    Missing timeout value.
	20314    Decryption Failed.
	20315    Missing password for decryption.
	20316    Not encrypted.
	20317    Security model not supported.
	20318    Defective packet
	20319    Not from bound point.
	20320    Operation not permitted in current role.
	20321    Bad packet.
	20322    Message not authenticated.
	20323    No such oid.
	20324    Missing privacy parameter.
	20325    Bad engine id.
	20326    Bad time frame.
	20327    Bad user name.
	20328    Security level was not accepted.
	20329    Discovery failed.
	20330    Incorrect key length.
	20331    No authentication password supplied.

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

UDP Errors

	20105    UDP is already Active.
	20107    You cannot change the LocalPort while the control is Active.
	20108    You cannot change the LocalHost at this time. A connection is in progress.
	20110    The control must be Active for this operation.
	20113    Cannot change MaxPacketSize while the control is Active.
	20114    Cannot change ShareLocalPort option while the control is Active.
	20115    Cannot change RemoteHost when UseConnection is set and the control Active.
	20116    Cannot change RemotePort when UseConnection is set and the control is Active.
	20117    RemotePort can't be zero when UseConnection is set. Please specify a valid service port number.
	20118    Cannot change UseConnection while the control is Active.
	20119    Message can't be longer than MaxPacketSize.
	20120    Message too short.
	20435    Unable to convert string to selected CodePage

SSL Errors

	20271    Cannot load specified security library.
	20272    Cannot open certificate store.
	20273    Cannot find specified certificate.
	20274    Cannot acquire security credentials.
	20275    Cannot find certificate chain.
	20276    Cannot verify certificate chain.
	20277    Error during handshake.
	20281    Error verifying certificate.
	20282    Could not find client certificate.
	20283    Could not find server certificate.
	20284    Error encrypting data.
	20285    Error decrypting data.

TCP/IP Errors

	25005    [10004] Interrupted system call.
	25010    [10009] Bad file number.
	25014    [10013] Access denied.
	25015    [10014] Bad address.
	25023    [10022] Invalid argument.
	25025    [10024] Too many open files.
	25036    [10035] Operation would block.
	25037    [10036] Operation now in progress.
	25038    [10037] Operation already in progress.
	25039    [10038] Socket operation on non-socket.
	25040    [10039] Destination address required.
	25041    [10040] Message too long.
	25042    [10041] Protocol wrong type for socket.
	25043    [10042] Bad protocol option.
	25044    [10043] Protocol not supported.
	25045    [10044] Socket type not supported.
	25046    [10045] Operation not supported on socket.
	25047    [10046] Protocol family not supported.
	25048    [10047] Address family not supported by protocol family.
	25049    [10048] Address already in use.
	25050    [10049] Can't assign requested address.
	25051    [10050] Network is down.
	25052    [10051] Network is unreachable.
	25053    [10052] Net dropped connection or reset.
	25054    [10053] Software caused connection abort.
	25055    [10054] Connection reset by peer.
	25056    [10055] No buffer space available.
	25057    [10056] Socket is already connected.
	25058    [10057] Socket is not connected.
	25059    [10058] Can't send after socket shutdown.
	25060    [10059] Too many references, can't splice.
	25061    [10060] Connection timed out.
	25062    [10061] Connection refused.
	25063    [10062] Too many levels of symbolic links.
	25064    [10063] File name too long.
	25065    [10064] Host is down.
	25066    [10065] No route to host.
	25067    [10066] Directory not empty
	25068    [10067] Too many processes.
	25069    [10068] Too many users.
	25070    [10069] Disc Quota Exceeded.
	25071    [10070] Stale NFS file handle.
	25072    [10071] Too many levels of remote in path.
	25092    [10091] Network subsystem is unavailable.
	25093    [10092] WINSOCK DLL Version out of range.
	25094    [10093] Winsock not loaded yet.
	26002    [11001] Host not found.
	26003    [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
	26004    [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
	26005    [11004] Valid name, no data record (check DNS setup).