powershellactive-directorymac-address

Adding only real MAC address

During the course of the work day I have field techs out and about and they'll occasionally need to add a MAC address to our Wireless Access group in AD. We don't fully support them getting into AD on their own and we've been using a script to allow them to add MAC addresses the right way. I have taken it upon myself to fully idiot-proof this thing and i'm nearly there minus one glaring issue. I can't stop them from adding MAC addresses with values greater than 'f'.

Write-Host "MAC Address must be entered as lowercase and without colons. EX: 14d6aa6ac9be" -ForegroundColor Yellow
    $MACUserName = Read-Host -Prompt 'Please Input the MAC Address of the Device to be added to AD and press Enter'
    $MACUserName = $MACUserName -replace '[\W]', ''
    If ($MACUserName.Length -ne 12 -or $MACUserName -notmatch '[A-Za-z0-9]') {
        Write-Host "MAC Address: " -ForegroundColor Red -NoNewline; Write-Host $MACUserName -ForegroundColor White -NoNewline; Write-Host " is not the correct length or contains invalid characters. Please verify MAC address" -ForegroundColor Red
        Pause
        Single-Device}

This is where i'm at with everything so far, obviously there is much more to this than just this section but for now this is where i live.

I'm able to get rid of any colons that might be entered in and my -notmatch section includes all possible values.

if i change -notmatch '[A-Za-z0-9]' to -notmatch '[A-Fa-f0-9]' It still lets me add fake MAC addresses with z's and whatnot. How do I go about limiting the characters this section will accept?

Solution

  • Santiago Squarzon's helpful answer offers the best solution to your problem, using a .NET API.

    As for what you tried:

    '[A-Fa-f0-9]' matches one character that falls into the specified ranges, which means that one such character in the input string makes the expression evaluate to $true - even if other characters outside these ranges are present.

    Therefore you must make sure that all characters that make up the input string fall into the expected ranges:

    -notmatch '^[a-f0-9]+$'

    Alternatively, invert the logic and look for at least one invalid character:

    -match '[^a-f0-9]'

    Note: