Re: [Doh] [Ext] Fallback to untrusted DOH servers
Mateusz Jończyk <mat.jonczyk@o2.pl> Mon, 23 April 2018 12:57 UTC
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To: Patrick McManus <pmcmanus@mozilla.com>
Cc: Paul Hoffman <paul.hoffman@icann.org>, DoH WG <doh@ietf.org>
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From: Mateusz Jończyk <mat.jonczyk@o2.pl>
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Date: Mon, 23 Apr 2018 14:56:46 +0200
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Subject: Re: [Doh] [Ext] Fallback to untrusted DOH servers
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What I am discussing here are modifications to DOH so that adding support for discovery would be possible without modifying the future RFC. Thanks, Mateusz Jończyk W dniu 23.04.2018 o 14:40, Patrick McManus pisze: > I really think you are discussing discovery. The chairs have said that is out of > scope for this draft but they are soliciting proposals for new work that could > include it. > > On Mon, Apr 23, 2018, 06:04 Mateusz Jończyk <mat.jonczyk@o2.pl > <mailto:mat.jonczyk@o2.pl>> wrote: > > W dniu 22.04.2018 o 17:15, Paul Hoffman pisze: > > On Apr 22, 2018, at 6:21 AM, Mateusz Jończyk <mat.jonczyk@o2.pl > <mailto:mat.jonczyk@o2.pl>> wrote: > >> I think if Your interpretation of DOH is correct, that the text is > unclear there > >> and should be clarified. > >> I would suggest to add the following clarification: > >> > >> A client MAY use an untrustworthy DNS API server as a fallback. > > > > This seems horribly dangerous without a clear definition of "fallback". > > There was a definition of "fallback" in a modification I proposed several mails > ago, but I removed it for sake of simplicity. > > So, I would propose a following addition: > A client MAY use an untrustworthy > DNS API server as a fallback, for example: when no trustworthy DNS API > server is configured, no configured DNS server works or > when the trustworthy DNS API server returned NXDOMAIN (and the client > checks whether an untrustworthy DNS API server would resolve the address in > question). > > The client MUST use separate DNS API caches for trustworthy and untrustworthy > DNS API servers or drop DNS caches when switching from an untrustworthy > DNS API server to a trustworthy one. > > Ted Lemon suggested in a private e-mail that contacting an untrusworthy DNS API > server after the trustworthy DNS API server returned NXDOMAIN exposes all > mistyped domains to the untrustworthy DNS API server. This is a valid concern, > and applies equally well to using old-school DNS in such a situation. > > I would therefore propose to add the following warning after the phrase: > "If a client of this protocol encounters an HTTP error after sending a > DNS query, and then falls back to a different > DNS retrieval mechanism, doing so can weaken the privacy and > authenticity expected by the user of the client." > > When a DNS API server returns NXDOMAIN, a client may wish to check > whether another server will resolve the domain name (as this may be > a local name to be resolved by a local DNS server). Doing so will, > however, expose all mistyped domain to that server. > > > > > >> I am going to submit a draft that specifies how a fallback DNS API server > could > >> be retrieved from DHCP. > > > > That would be quite useful. If you do that, wouldn't it define the DNS API > server as trusted? > > No, the server retrieved via DHCP is going to an untrustworthy DNS API server > (as defined above) as DHCP is usually unauthenticated and prone to various > manipulations. > > > > > --Paul Hoffman > > > > Greetings, > Mateusz Jończyk > _______________________________________________ > Doh mailing list > Doh@ietf.org <mailto:Doh@ietf.org> > https://www.ietf.org/mailman/listinfo/doh >
- [Doh] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] Fallback to untrusted DOH servers Ted Lemon
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Paul Hoffman
- Re: [Doh] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Patrick McManus
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Paul Hoffman
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Patrick McManus
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Mateusz Jończyk
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Paul Hoffman
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Ben Schwartz
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Ted Lemon
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Tom Pusateri
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Paul Hoffman
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Tom Pusateri
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Ted Lemon
- Re: [Doh] [Ext] Fallback to untrusted DOH servers Tom Pusateri
- [Doh] Goals of DOH Paul Hoffman
- Re: [Doh] Goals of DOH Ted Lemon
- Re: [Doh] [Ext] Goals of DOH Paul Hoffman
- Re: [Doh] [Ext] Goals of DOH Ted Lemon