Re: [apps-discuss] Aggregated service discovery

Michiel de Jong <> Tue, 29 May 2012 12:23 UTC

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Date: Tue, 29 May 2012 14:22:59 +0200
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From: Michiel de Jong <>
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Cc:, Alessandro Vesely <>
Subject: Re: [apps-discuss] Aggregated service discovery
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in the remoteStorage spec we are using webfinger to discover a
personal data service. relying on network topology for security is not
an option here, and nor are SRV records, because we want to be able to
link any unhosted html5 app to any remoteStorage server. This is still
very much a draft, and we're still changing the link format around,
but our current proposal is this:

Basically, our example (publicly) announces the following service
attributes for a Read-Write Web (rww) server over public

- service base address
- service API version
- auth method
- auth end-point

I would love to get feedback on they way we're doing that discovery
there, and if anybody knows a more standard way to achieve the same


On Sun, May 27, 2012 at 5:43 AM, Andrew McMillan <> wrote:
> On Fri, 2012-05-25 at 10:15 +0200, Alessandro Vesely wrote:
>> On Thu 24/May/2012 16:30:03 +0200 Michiel de Jong wrote:
>> > but the main objection people would have to doing this is i think
>> > privacy/security. you don't want to announce the exact details of all
>> > your services publically, because:
>> > 1) it makes it easier for an attacker to know where to attack your systems
>> > 2) it may reveal non-public information about your users unnecessarily.
>> Requiring authentication in order to discover the services would seem
>> to be a relevant functional difference w.r.t. SRV records.  I, for
>> one, don't use SRV records because of those two reasons.
> I can definitely understand that reasoning, and it's a good point in
> favour of a more securable alternative.  You could also make the
> relevant SRV records available only on your private networks, but then
> that can result in a complex and fragile DNS setup.
>> Of course, directing all mass, blind dictionary attacks toward a
>> single entry point will call from some savvy implementation advice.
>> For example, centralized discovery could count failed attempts and
>> block a user when that number becomes comparable to her password's
>> entropy.  She won't be able to install new client devices for a while,
>> but that is much less disruptive than blocking IMAP access.
> I can see plenty of value in an administrator putting the discovery
> point inside a corporate (or ISP) firewall in order to reduce the value
> to automated external attackers.  Or having alternative representations
> of the discovery with only limited visible services for external
> visitors.  Analogously, a manual system of providing these configuration
> parameters could well place them inside a firewall on internal
> documentation.
> I would like to see a scheme which had significant utility with only a
> single static document providing the information.  More advanced
> implementations may well produce that document dynamically, but these
> parameters are not expected to be very changeable values in most
> installations.
> Regards,
>                                        Andrew.
> --
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> andrew (AT) morphoss (DOT) com                            +64(272)DEBIAN
>        Open Source: the difference between trust and antitrust
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