I am writing a script which will create backup schedules in 2008/2008R2. I am using get-credentials cmdlet and storing in a $cred variable and using $cred later in the script to run the scheduled jobs.

While the script is running fine, there are few missing things like verification and validation. I want to know how we can add these into the script for ex.: I want to first validate if the credential provided was correct and was Successfully authenticated by AD and once the credentials are validated, the script should look for a mandatory users group membership information, i.e. if the user is a member of US Admins group, only then proceed with the script else terminate with an intuitive error message. Can this be done? if so can you provide me some assistance here.

Here is a snippet of my code for which i want to add authentication and authorization mechanism

#Gets the backup scheduler credentials from the user
"Enter Credentials of the RMAD Backup Account in the format"
"Domain\User"
Write-host
$cred=get-credential
#create an array of Domain Controllers by reading from a text file
$dclist=get-content DCListing.txt

#Create an array of RMAD Collections
$col="Daily","Weekly","Monthly","Adhoc"

#Looping through the RMAD collections and adding the Domain Controllers to each collection
#and checking empty spaces or null value in the dclist.txt file

#Define iteration variables
$i=0
$j=0

foreach($objitem in $col)
{
new-rmadcollection -name $col[$i]
foreach($objitem2 in $dclist)
{
if($dclist -eq '') {}
Elseif($dclist -eq $null) {}
Else{add-rmadcollectionitem -Collection $col[$i] -DomainController $dclist[$j]}
$j++
}
$j=0
$i++
}

#Set the date and time for run Backup Schedules - Modify the date and time accordingly
$date1="4/1/2009 9:00:00 AM"
$date2="4/1/2009 9:00:00 PM"

Check this script: Test-ADCredentials http://poshcode.org/1393