On Mon, 19 Feb 2007, Edward Lewis wrote: > At 10:55 +0000 2/19/07, Tony Finch wrote: > > > > It allows you to use a DNS server to tunnel past a firewall. It allows you > > to use a DNS server to probe a private network. > > How?
If you point NS records at private networks then you can get DNS servers to send queries to their private networks. The timing of any responses you get might give you some information about their network topology, e.g. which hosts are up, etc. More interestingly, consider a user on a private network that is heavily firewalled (not even NAT connectivity to the Internet) and who wants to tunnel out. If there is a nameserver connected to the internal and external networks, and the user can persuade it to make a query controlled by the user, then the user can get it to recurse back and forth between a public IP address and the user's private IP address, passing data in the process. Note that the user does not require direct access to a recursive resolver: for example, they could trigger the query by saying HELO to a mail server. One trigger query can result in several back-and-forth exchanges via the tunnel. Tony. -- f.a.n.finch <[EMAIL PROTECTED]> http://dotat.at/ MALIN HEBRIDES: SOUTHEAST 5 OR 6, INCREASING 7 OR GALE 8. ROUGH OR VERY ROUGH. OCCASIONAL RAIN. MODERATE OR GOOD. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www1.ietf.org/mailman/listinfo/dnsop
