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Re: [ietf] DNS spoofing at captive portals

2010-09-24 14:47:57

On Sep 24, 2010, at 8:38 AM, Alfred HÎnes wrote:

At Fri, 24 Sep 2010 07:21:21 -0400,  Michael Richardson wrote:

Has the IETF (or rather then IAB) written any simple documents that
explain to less informed (i.e. marketing/product) managers why it
is a bad thing for a captive portal to spoof DNS replies?
(not just in regard to DNSSEC, but also in regards to just caching)

a) Most of the arguments explained in the 2003 IAB Commentary:
  "Architectural Concerns on the use of DNS Wildcards",
  <http://www.IAB.ORG/documents/docs/2003-09-20-dns-wildcards.html>,
  apply in a similar fashion, but it indeed would be a good idea
  to produce such document.  I think much text from 2003 could
  be leveraged.

One important thing to realize is that this kind of "service" isn't always 
implemented using wildcards.  Sometimes the "service" is implemented using 
interception proxies.

b) It should be clearly spelled out that this practice falls among the
  category of actions commonly known as man-in-the-middle attacks.

Agreed.  Actually, when a server or interception proxy deliberately 
misrepresents the contents of others' DNS zones, the appropriate term (IMO) is 
"fraud".   

IANAL but would think that such practice should expose the operator of the 
server or proxy to civil and/or criminal action, both from the operators of the 
zones whose RRs are being misrepresented, and from the users' whose 
applications are affected.

c) draft-livingood-dns-redirect and draft-livingood-dns-malwareprotect
  descibe these "services" in a much too friendly tone;

Strongly agree, at least for the -redirect draft.  At the very least, a 
distinction needs to be made between services which the individual user 
deliberately chooses, and services which are imposed without the users' 
knowledge or consent.  The draft also glosses over the problems created by this 
practice for all applications other than web browsing by human beings.   Not 
only does this provide misleading error indications for all other applications, 
it even breaks applications that are layered on top of HTTP.

d) In my personal opinion, the original idea of having recursive
  DNS resolvers located "close to the hosts" should be given more
  traction again in the future.  All kinds of SOHO access gateways
  or home gateways should preferably offer (locally) full recursive
  and validating DNS resolution service.

Agree with this also.  In many cases the ideal model seems to be one in which 
the host serves as its own primary DNS server, or at least as the master DNS 
zone. 

Keith

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