public/Set-SnmpData.ps1

<#
.SYNOPSIS
Sets the value of a writable SNMP OID on a target device.

.DESCRIPTION
Sets the value of a writable OID on an SNMP-enabled device using
SNMP v1, v2c or v3.

The cmdlet supports multiple SNMP data types and returns the value
reported by the device after the operation.

Supports -WhatIf and -Confirm for safe execution.

.PARAMETER ComputerName
Hostname or IP address of the target device.

.PARAMETER Port
UDP port used for SNMP communication (default is 161)

.PARAMETER Oid
OID to modify.

.PARAMETER NewValue
The new value to assign to the specified OID.

The value is converted to the SNMP data type specified by
the DataType parameter.

.PARAMETER DataType
Specifies the SNMP data type used when setting the value.

Supported values include:
- OctetString
- Integer32
- Gauge32
- Counter32
- Unsigned32
- TimeTicks
- IpAddress

If omitted, OctetString is used.

.PARAMETER Timeout
The timeout value in milliseconds.
0 and -1 indicate an infinite timeout.

.PARAMETER Version
SNMP version to use (V1, V2C or V3)

.PARAMETER Community
SNMP community string (Only V1 or V2C)

.PARAMETER Username
SNMPv3 user name (Only V3)

.PARAMETER AuthenticationProtocol
SNMPv3 authentication protocol (Only V3)

.PARAMETER AuthenticationPassword
SNMPv3 authentication password (Only V3)

.PARAMETER PrivacyProtocol
SNMPv3 privacy protocol (Only V3)

.PARAMETER PrivacyPassword
SNMPv3 privacy password (Only V3)

.EXAMPLE
Set-SnmpData `
    -ComputerName switch01 `
    -Oid '1.3.6.1.x.x.x' `
    -NewValue 'Printer'

Sets the specified OID to the string value 'Printer'.

.EXAMPLE
Set-SnmpData `
    -ComputerName switch01 `
    -Oid '1.3.6.1.x.x.x' `
    -NewValue 1 `
    -DataType Integer32

Sets the specified OID to the Integer32 value 1.

.EXAMPLE
Set-SnmpData `
    -ComputerName switch01 `
    -Oid '1.3.6.1.x.x.x' `
    -NewValue '192.168.1.100' `
    -DataType IpAddress

Sets the specified OID to the IP address 192.168.1.100.

.EXAMPLE
Set-SnmpData `
    -ComputerName switch01 `
    -Oid '1.3.6.1.x.x.x' `
    -NewValue 'NewLocation' `
    -WhatIf

Shows what would happen without sending the SNMP SET request.

.OUTPUTS
SnmpTools.SnmpData

.NOTES
This cmdlet only supports single OID SET operations.

SNMP SET requests require the target OID to be writable and
the supplied credentials to have write permissions.
#>

function Set-SnmpData
{
    [OutputType('SnmpTools.SnmpData')]
    [CmdletBinding(
        DefaultParameterSetName = 'Community',
        SupportsShouldProcess = $true
    )]
    param (
        # General required parameters
        [Parameter(Mandatory)]
        [Alias('IPAddress')]
        [string]$ComputerName,

        [Parameter()]
        [ValidateRange(1,65535)]
        [int]$Port = 161,

        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string]$Oid,

        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [object]$NewValue,

        [Parameter()]
        [SnmpDataType]$DataType = [SnmpDataType]::OctetString,

        [Parameter()]
        [ValidateRange(-1,2147483647)]
        [int]$Timeout = 5000,

        [Parameter(ParameterSetName = 'Community')]
        [Parameter(ParameterSetName = 'V3')]
        [SnmpVersion]$Version = [SnmpVersion]::V2C,

        # Parameter for SNMP version v1 and v2, both rely on a set community
        [Parameter(ParameterSetName = 'Community')]
        [string]$Community = 'public',

        # Parameters for SNMP version v3
        [Parameter(Mandatory, ParameterSetName = 'V3')]
        [string]$Username,

        [Parameter(ParameterSetName = 'V3')]
        [ValidateSet(
            'MD5',
            'SHA1',
            'SHA256',
            'SHA384',
            'SHA512'
        )]
        [string]$AuthenticationProtocol,

        [Parameter(ParameterSetName = 'V3')]
        [securestring]$AuthenticationPassword,

        [Parameter(ParameterSetName = 'V3')]
        [ValidateSet(
            'DES',
            '3DES',
            'AES',
            'AES192',
            'AES256'
        )]
        [string]$PrivacyProtocol,

        [Parameter(ParameterSetName = 'V3')]
        [securestring]$PrivacyPassword
    )

    begin {
        Write-Verbose "Selected parameter set: $($PSCmdlet.ParameterSetName)"

        # Validate ParameterSet and Version combination
        if($PSCmdlet.ParameterSetName -eq 'Community' -and $Version -eq [SnmpVersion]::V3) {
            throw "SNMP version V3 cannot be used with the Community parameter set."
        }
        if ($PSCmdlet.ParameterSetName -eq 'V3' -and $Version -ne [SnmpVersion]::V3) {
            throw "Parameter set 'V3' requires -Version V3."
        }

        # Authentication pair validation
        if ($AuthenticationProtocol -and -not $AuthenticationPassword) {
            throw "AuthenticationPassword is required when AuthenticationProtocol is specified."
        }

        if ($AuthenticationPassword -and -not $AuthenticationProtocol) {
            throw "AuthenticationProtocol is required when AuthenticationPassword is specified."
        }

        # Privacy pair validation
        if ($PrivacyProtocol -and -not $PrivacyPassword) {
            throw "PrivacyPassword is required when PrivacyProtocol is specified."
        }

        if ($PrivacyPassword -and -not $PrivacyProtocol) {
            throw "PrivacyProtocol is required when PrivacyPassword is specified."
        }

        # Privacy without Authentication is not possible
        if (($PrivacyProtocol -or $PrivacyPassword) -and -not $AuthenticationProtocol) {
            throw "Privacy settings require authentication."
        }

        # Validate supplied address and resolve endpoint
        $Endpoint = Resolve-SnmpEndpoint -ComputerName $ComputerName -Port $Port

        # Resolve SNMP version code
        $VersionCode = Resolve-SnmpVersion $Version

        # Set the timestamp
        $Timestamp = Get-Date
    }

    process {
        # Add support for -WhatIf and -Confirm
        if (-not $PSCmdlet.ShouldProcess(
            "$ComputerName ($Oid)",
            "Set value to '$NewValue'"
        )) {
            return
        }
        
        # Create a list of variable to send in SNMP communication to the endpoint
        $Variables = [System.Collections.Generic.List[Lextm.SharpSnmpLib.Variable]]::new()
        $Variables.Add(
            [Lextm.SharpSnmpLib.Variable]::new(
                [Lextm.SharpSnmpLib.ObjectIdentifier]::new($Oid),
                (Resolve-SnmpDataType -DataType $DataType -Value $NewValue)
        ))

        # Start communication depending on SNMP version
        switch ($PSCmdlet.ParameterSetName) {
            'Community' {
                try {
                    $data = [Lextm.SharpSnmpLib.Messaging.Messenger]::Set($VersionCode, $Endpoint, $Community, $Variables, $Timeout)
                } catch {
                    throw "SNMP $Version error: $($_.Exception.Message)"
                }
            }

            'V3' {
                # Build auth and privacy providers
                $AuthProvider = Resolve-SnmpAuthenticationProvider `
                    -AuthenticationProtocol $AuthenticationProtocol `
                    -AuthenticationPassword $AuthenticationPassword
                $PrivacyProvider = Resolve-SnmpPrivacyProvider `
                    -AuthenticationProvider $AuthProvider `
                    -PrivacyProtocol $PrivacyProtocol `
                    -PrivacyPassword $PrivacyPassword

                # SNMP Discovery
                try {
                    $Discovery = [Lextm.SharpSnmpLib.Messaging.Messenger]::GetNextDiscovery([Lextm.SharpSnmpLib.SnmpType]::SetRequestPdu)
                    $Report = $Discovery.GetResponse($Timeout, $Endpoint)
                } catch {
                    throw "SNMP $Version discovery failed: $($_.Exception.Message)"
                }

                # SNMP Request
                try {
                    $Request = [Lextm.SharpSnmpLib.Messaging.SetRequestMessage]::new(
                        $VersionCode,
                        [Lextm.SharpSnmpLib.Messaging.Messenger]::NextMessageId,
                        [Lextm.SharpSnmpLib.Messaging.Messenger]::NextRequestId,
                        [Lextm.SharpSnmpLib.OctetString]::new($Username),
                        $Variables,
                        $PrivacyProvider,
                        $Report
                    )
                    $Reply = [Lextm.SharpSnmpLib.Messaging.SnmpMessageExtension]::GetResponse(
                        $Request,
                        $Timeout,
                        $Endpoint
                    )
                } catch {
                    throw "SNMP $Version request failed $($_.Exception.Message)"
                }

                # Check for agent errors
                if ($Reply.Scope.Pdu.ErrorStatus.ToInt32() -ne 0) {
                    throw (
                        "SNMP {0} error returned by device {1}. ErrorStatus: {2}, ErrorIndex: {3}" -f
                        $Version,
                        $Endpoint.Address,
                        $Reply.Scope.Pdu.ErrorStatus,
                        $Reply.Scope.Pdu.ErrorIndex
                    )
                }
                $data = $Reply.Scope.Pdu.Variables
            }

            default {
                throw "Unsupported parameter set: $($PSCmdlet.ParameterSetName)"
            }
        }

        #
        # Return objects
        #
        foreach ($Variable in $data) {
            New-SnmpDataObject `
                -ComputerName $ComputerName `
                -Variable $Variable `
                -Version $Version `
                -Timestamp $Timestamp
        }
    }
}