On Wed, Nov 11, 2015 at 12:42:17PM +0100, Georg Lukas wrote:
> * Dave Cridland <[email protected]> [2015-11-11 08:58]:
> > > What do you suggest to replace it with?
> > [...] we need, I think, a mechanism which takes a potential new user
> > through new account creation, and helps in configuring their client,
> > and ideally works across multiple servers.
> 
> And it needs to be as easy as WhatsApp. I don't see a mechanism that
> will effectively prevent automatic registrations, that doesn't rely on
> a scarce out-of-band resource like cellphone numbers.
> 
> While spam is evil, it won't be solved by deprecating IBR, especially as
> it will take many more years until all the servers out there have
> adopted the new alternative.
> 
> I think we as a community must develop better mechanisms for spam
> detection and prevention, maybe in the form of massive throttling of
> incoming c2s and s2s message flows, maybe by improving our monitoring,
> maybe by other means.
> 
> I actually like Dave's suggestion from the other thread, to disallow
> message sending from untrusted users. What about the following approach:
> 
> 1. User registers with IBR
> 2. User sends message
> 3. Server (local or remote) flags user as potential spammer
> 4. Server stores undelivered message, gives the user a captcha to solve
>    (via a HTTP(S) link)
> 5. User solves captcha
> 6. Server forwards/delivers messages
> 
> #3 and #4 could be deployed on c2s and s2s links using different
> metrics, and could be repeated more than once if the user is considered
> evil.
> 
> C2S:
>  - age of the account
>  - IP address reputation (RBL / accounts from that IP / ...)
>  - number of messages sent vs. received
>  - roster size
> 
> S2S:
>  - number of messages received from the remote account vs. sent back
>  - number of "first contacts" (unsolicited messages) from different
>    accounts on this server
>  - if that other server offers IBR

Those metrics are already specified in XEP-0275 section 3, fyi.

> 
> 
> Example:
> 
> 1. Juliet registers [email protected]
> 2. Juliet sends "Hi" to [email protected]
> 3. montague.com thinks something is fishy.
> 4. The montague.com server responds with
>    "Your message to [email protected] must be unlocked. Please solve
>    the captcha on https://montague.com/xmpp/captcha?refid=too5cupoeN
>    and your message will be forwarded."
> 5. Juliet makes a dozen attempts and finally enters a valid text
> 6. montague.com delivers Juliet's "Hi", and also sends back to her:
>    "Thank you for your approval. 1 message has been forwarded."
> 
> This approach could be codified in an XEP, but it can be deployed with
> what we have today.

This happen to be exactly what XEP-0158 is about. :)

> 
> Servers could even exchange information about which remote servers /
> accounts they consider how trustworthy, provided that the security
> implications of passing along third-party account names are addressed.

I think XEP-0267 and XEP-0268 might be relevant.

> 
> 
> Georg
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-- 
Emmanuel Gil Peyrot

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