iRule to reject a specific activesync DeviceId

Part of the iRule. It seems the HTTP header command is case insensitive about the header name but not it's value. If you ensure the string your matching against is lower case we can avoid doing the conversion to lower case twice. I've added some logging too which you can remove or comment out later;

when HTTP_REQUEST {
 if { [string tolower [HTTP::header value "DeviceId"]] equals "samsungxyz123" } {
  drop
  log local0. "Dropped a request from [HTTP::header value "DeviceId"]"
 } 
}