public/Get-SnmpNext.ps1
|
<# .SYNOPSIS Retrieves the next OID in the SNMP MIB tree. .DESCRIPTION Retrieves the next available OID after the specified OID using an SNMP GETNEXT request. This cmdlet supports SNMP v1, v2c and v3 and returns the next variable together with its value. Get-SnmpNext can be used to explore MIB trees and serves as the foundation for MIB walking operations. .PARAMETER ComputerName Hostname or IP address of the target device. .PARAMETER Port UDP port used for SNMP communication (default is 161). .PARAMETER Oid The starting OID. The cmdlet returns the next OID and its value after the specified OID. .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 Get-SnmpNext ` -ComputerName switch01 ` -Oid '1.3.6.1.2.1.1' Returns the next OID and value after 1.3.6.1.2.1.1. .EXAMPLE Get-SnmpNext ` -ComputerName switch01 ` -Oid '1.3.6.1.2.1.1.5.0' ` -Community public ` -Version V2C Returns the next OID after sysName.0 using SNMPv2c. .EXAMPLE Get-SnmpNext ` -ComputerName switch01 ` -Oid '1.3.6.1.2.1.1' ` -Version V3 ` -Username snmpuser ` -AuthenticationProtocol SHA256 ` -AuthenticationPassword $AuthPassword Returns the next OID using SNMPv3 authentication. .OUTPUTS SnmpTools.SnmpData .NOTES Uses an SNMP GETNEXT request to retrieve the next OID in lexicographical order. This cmdlet returns a single result and can be used as the foundation for implementing SNMP walk operations. #> function Get-SnmpNext { [OutputType('SnmpTools.SnmpData')] [CmdletBinding( DefaultParameterSetName = 'Community' )] param ( # General required parameters [Parameter(Mandatory)] [Alias('IPAddress')] [string]$ComputerName, [Parameter()] [ValidateRange(1,65535)] [int]$Port = 161, [Parameter(Mandatory)] [ValidateNotNullOrEmpty()] [string]$Oid, [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 { # 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) )) # Start communication depending on SNMP version switch ($PSCmdlet.ParameterSetName) { 'Community' { try { # SharpSnmpLib doesn't expose a Messenger.GetNext(), so using Messaging.GetNextRequestMessage instead. $Request = [Lextm.SharpSnmpLib.Messaging.GetNextRequestMessage]::new( [Lextm.SharpSnmpLib.Messaging.Messenger]::NextRequestId, $VersionCode, [Lextm.SharpSnmpLib.OctetString]::new($Community), $Variables ) } catch { throw "SNMP $Version request failed: $($_.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]::GetNextRequestPdu) $Report = $Discovery.GetResponse($Timeout, $Endpoint) } catch { throw "SNMP $Version discovery failed: $($_.Exception.Message)" } # SNMP Request try { $Request = [Lextm.SharpSnmpLib.Messaging.GetNextRequestMessage]::new( $VersionCode, [Lextm.SharpSnmpLib.Messaging.Messenger]::NextMessageId, [Lextm.SharpSnmpLib.Messaging.Messenger]::NextRequestId, [Lextm.SharpSnmpLib.OctetString]::new($Username), $Variables, $PrivacyProvider, $Report ) } catch { throw "SNMP $Version request failed: $($_.Exception.Message)" } } default { throw "Unsupported parameter set: $($PSCmdlet.ParameterSetName)" } } # Get SNMP response try { $Reply = [Lextm.SharpSnmpLib.Messaging.SnmpMessageExtension]::GetResponse( $Request, $Timeout, $Endpoint ) } catch { throw "SNMP $Version reply error: $($_.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 ) } # Return objects $data = $Reply.Scope.Pdu.Variables foreach ($Variable in $data) { New-SnmpDataObject ` -ComputerName $ComputerName ` -Variable $Variable ` -Version $Version ` -Timestamp $Timestamp } } } |