Problème :

Il existe une limitation à la commande "Get-ADGroupMember" et cette dernière est de 5000, ce qui veut dire que si le groupe détient plus de 5000 membres vous obtiendrez un joli message d'erreur du type :

Get-ADGroupMember : The size limit for this resquest was exceeded

Solution :

Voici une fonction Powershell qui vous permettra de récupérer l'intégralité des membres d'un groupe même s'il y en a 10 000 dedans.

Vous pourrez choisir de retourner :

• Les utilisateurs
• Les groupes
• Le tout

Function Get-AllMembers {
     <#
    .SYNOPSIS
    Return a list of members for a group.

    .DESCRIPTION
    Get-AllMembers is a function that returns a list of members for a specific group.
    
    .PARAMETER Name
    The name of the group you want to get the member list.

    .EXAMPLE
    Get-AllMembers "Domain Admins", "DNS Admins"

    .INPUTS
    String

    .OUTPUTS
        PSCustomObject

    .NOTES
        Author:  ADELAIDE Mathieu
    #>
    PARAM (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true, Position = 0)]
        [STRING]$Name,
        [Parameter(Mandatory = $true, ValueFromPipeline = $true, Position = 1)]
        [ValidateSet("UsersOnly","GroupsOnly","All")]
        [STRING]$Return
        )
    Process {
        $Name | Foreach {
            $GroupName = $_
            $ArrayUsers = @()
            $ArrayGroups = @()
            $ArrayAll = @()
            Try {
                $DistinguishedName = Get-ADGroup -Identity $GroupName -ErrorAction Stop | select -ExpandProperty DistinguishedName
                # Searching all Users who's member of current Group
                Try {
                    $AllUsersMembers = Get-ADUser -LDAPFilter "(&(objectCategory=user)(memberOf=$DistinguishedName))" -ErrorAction Stop
                    $AllUsersMembers | foreach {
                        $ArrayUsers += New-Object psobject -Property @{
                            GroupName = $GroupName
                            DistinguishedName = $_.DistinguishedName
                            Enabled = $_.Enabled
                            GivenName = $_.GivenName
                            Name = $_.Name
                            ObjectClass = $_.ObjectClass
                            ObjectGUID = $_.ObjectGUID
                            SamAccountName = $_.SamAccountName
                            SID = $_.SID
                            Surname = $_.Surname
                            UserPrincipalName = $_.UserPrincipalName
                            }

                        # Collect All
                        $ArrayAll += New-Object psobject -Property @{
                            GroupName = $GroupName
                            DistinguishedName = $_.DistinguishedName
                            Enabled = $_.Enabled
                            GivenName = $_.GivenName
                            Name = $_.Name
                            ObjectClass = $_.ObjectClass
                            ObjectGUID = $_.ObjectGUID
                            SamAccountName = $_.SamAccountName
                            SID = $_.SID
                            Surname = $_.Surname
                            UserPrincipalName = $_.UserPrincipalName
                            }
                        }
                    }
                Catch {
                    Write-Warning -Message "Unable to find all users member of $Name"
                    }
                # Searching all Groups who's member of current Group
                Try {
                    $AllGroupsMembers = Get-ADGroup -LDAPFilter "(&(objectCategory=group)(memberOf=$DistinguishedName))" -ErrorAction Stop
                    $AllGroupsMembers | foreach {
                        $ArrayGroups += New-Object psobject -Property @{
                            GroupName = $GroupName
                            DistinguishedName = $_.DistinguishedName
                            GroupCategory = $_.GroupCategory
                            GroupScope = $_.GroupScope
                            Name = $_.Name
                            ObjectClass = $_.ObjectClass
                            ObjectGUID = $_.ObjectGUID
                            SamAccountName = $_.SamAccountName
                            SID = $_.SID
                            }

                        # Collect All
                        $ArrayAll += New-Object psobject -Property @{
                            GroupName = $GroupName
                            DistinguishedName = $_.DistinguishedName
                            Enabled = $_.Enabled
                            GivenName = $_.GivenName
                            Name = $_.Name
                            ObjectClass = $_.ObjectClass
                            ObjectGUID = $_.ObjectGUID
                            SamAccountName = $_.SamAccountName
                            SID = $_.SID
                            Surname = $_.Surname
                            UserPrincipalName = $_.UserPrincipalName
                            }
                        }
                    }
                Catch {
                    # Return an error message if member not found.
                    Write-Warning -Message "Unable to find all groups member of $Name"
                    }
                }
            Catch {
                # Return an error message if Group was not found.
                Write-Warning -Message "Unable to find $Name"
                }
            
            Switch ($Return) {
                "UsersOnly" {Return $ArrayUsers}
                "GroupsOnly" {Return $ArrayGroups}
                "All" {Return $ArrayAll}
                }

            # Release
            $GroupName = $null
            $DistinguishedName = $null
            $AllUsersMembers = $null
            $AllGroupsMembers = $null
            }
        }
    }