functions/Test-DbaConnectionAuthScheme.ps1

function Test-DbaConnectionAuthScheme {
    <#
        .SYNOPSIS
            Returns the transport protocol and authentication scheme of the connection. This is useful to determine if your connection is using Kerberos.
             
        .DESCRIPTION
            By default, this command will return the ConnectName, ServerName, Transport and AuthScheme of the current connection.
             
            ConnectName is the name you used to connect. ServerName is the name that the SQL Server reports as its @@SERVERNAME which is used to register its SPN. If you were expecting a Kerberos connection and got NTLM instead, ensure ConnectName and ServerName match.
 
            If -Kerberos or -Ntlm is specified, the $true/$false results of the test will be returned. Returns $true or $false by default for one server. Returns Server name and Results for more than one server.
             
        .PARAMETER SqlInstance
            The SQL Server that you're connecting to. Server(s) must be SQL Server 2005 or higher.
             
        .PARAMETER Kerberos
            If this switch is enabled, checks will be made for Kerberos authentication.
 
        .PARAMETER Ntlm
            If this switch is enabled, checks will be made for NTLM authentication.
             
        .PARAMETER Detailed
            If this switch is enabled, a detailed list of authentication schemes and transport methods in use will be returned.
 
        .PARAMETER SqlCredential
            Allows you to login to servers using SQL Logins instead of Windows Authentication (AKA Integrated or Trusted). To use:
 
            $scred = Get-Credential, then pass $scred object to the -SqlCredential parameter.
 
            Windows Authentication will be used if SqlCredential is not specified. SQL Server does not accept Windows credentials being passed as credentials.
 
            To connect as a different Windows user, run PowerShell as that user.
 
            .PARAMETER Silent
            Use this switch to disable any kind of verbose messages
 
        .NOTES
            Tags: SPN, Kerberos
            dbatools PowerShell module (https://dbatools.io, clemaire@gmail.com)
            Copyright (C) 2016 Chrissy LeMaire
            License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
        .LINK
            https://dbatools.io/Test-DbaConnectionAuthScheme
 
        .EXAMPLE
            Test-DbaConnectionAuthScheme -SqlInstance sqlserver2014a, sql2016
 
            Returns ConnectName, ServerName, Transport and AuthScheme for sqlserver2014a and sql2016.
 
        .EXAMPLE
            Test-DbaConnectionAuthScheme -SqlInstance sqlserver2014a -Kerberos
 
            Returns $true or $false depending on if the connection is Kerberos or not.
             
        .EXAMPLE
            Test-DbaConnectionAuthScheme -SqlInstance sqlserver2014a -Detailed
 
            Returns the results of "SELECT * from sys.dm_exec_connections WHERE session_id = @@SPID"
         
    #>

    [CmdletBinding()]
    Param (
        [parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstanceParameter[]]$SqlInstance,
        [Alias("Credential", "Cred")]
        [PSCredential]$SqlCredential,
        [switch]$Kerberos,
        [switch]$Ntlm,
        [switch]$Detailed,
        [switch]$Silent
    )
    
    begin {
        $sql = "SELECT SERVERPROPERTY('MachineName') AS ComputerName,
                            ISNULL(SERVERPROPERTY('InstanceName'), 'MSSQLSERVER') AS InstanceName,
                            SERVERPROPERTY('ServerName') AS SqlInstance,
                            session_id as SessionId, most_recent_session_id as MostRecentSessionId, connect_time as ConnectTime,
                            net_transport as Transport, protocol_type as ProtocolType, protocol_version as ProtocolVersion,
                            endpoint_id as EndpointId, encrypt_option as EncryptOption, auth_scheme as AuthScheme, node_affinity as NodeAffinity,
                            num_reads as NumReads, num_writes as NumWrites, last_read as LastRead, last_write as LastWrite,
                            net_packet_size as PacketSize, client_net_address as ClientNetworkAddress, client_tcp_port as ClientTcpPort,
                            local_net_address as ServerNetworkAddress, local_tcp_port as ServerTcpPort, connection_id as ConnectionId,
                            parent_connection_id as ParentConnectionId, most_recent_sql_handle as MostRecentSqlHandle
                            from sys.dm_exec_connections WHERE session_id = @@SPID"

    }
    
    process {
        foreach ($instance in $SqlInstance) {
            
            try {
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $SqlCredential -MinimumVersion 9
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }
            
            Write-Message -Level Verbose -Message "Getting results for the following query: $sql."
            try {
                $results = $server.Query($sql)
            }
            catch {
                Stop-Function -Message "Failure" -Target $server -Exception $_ -Continue
            }
            
            # sorry, standards!
            if ($Kerberos -or $Ntlm) {
                if ($Ntlm) {
                    $auth = 'NTLM'
                }
                else {
                    $auth = 'Kerberos'
                }
                [PSCustomObject]@{
                    ComputerName    = $results.ComputerName
                    InstanceName    = $results.InstanceName
                    SqlInstance        = $results.SqlInstance
                    Result            = ($server.AuthScheme -eq $auth)
                } | Select-DefaultView -Property SqlInstance, Result
            }
            else {
                if ($detailed) {
                    $results
                }
                else {
                    Select-DefaultView -InputObject $results -Property ComputerName, InstanceName, SqlInstance, Transport, AuthScheme
                }
            }
        }
    }
}