[jdev] Securing XMPP

Thijs Alkemade thijs at xnyhps.nl
Fri Sep 6 18:16:05 UTC 2013


On 6 sep. 2013, at 20:04, Peter Saint-Andre <stpeter at stpeter.im> wrote:

> On 9/6/13 10:40 AM, Peter Saint-Andre wrote:
> > On 8/28/13 10:14 AM, Simon Tennant wrote:
> >> I'm attempting to gather the details in one place on how to
> >> secure XMPP servers C2S and S2S traffic:
> > 
> >> http://wiki.xmpp.org/web/Securing_XMPP
> > 
> > Thanks.
> > 
> > As you've seen from the news over the last 24 hours, things are
> > even worse than we thought.
> > 
> > Among other things, forcing the use of SSL/TLS is not enough. We
> > need to be careful about what ciphersuites we allow. Some of the
> > older, weaker ciphersuites need to be disabled (e.g., RC4 / MD5).
> > We need to start preferring ciphersuites that enable perfect
> > forward secrecy (PFS).
> 
> To be clear, those are suites with EDH/DHE/ECDH in the name. It would
> be interesting to see how widely those are supported in current XMPP
> software.
> 
> Peter

I have gathered some data on that:

https://blog.thijsalkema.de/blog/2013/08/26/the-state-of-tls-on-xmpp-1/
https://blog.thijsalkema.de/blog/2013/09/02/the-state-of-tls-on-xmpp-3/

29 of the 100 servers from xmpp.net that I could reach have at least one
ephemeral suite enabled.

All clients I've tested have some variant of EDH/DHE enabled. 8 of the 18
different client/OS combinations have ECDHE enabled.

However, a large number of clients do not prioritize (EC)DHE above the non-
ephemeral variants. To enforce that these are used, it is therefore required
to either disable all non-ephemeral suites or configure the server to override
the client's order with the server's order.

Regards,
Thijs

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