Re: SSL SNI

Hi Peter,
I imagine this also (finally) opens up the possibility for the server
to present a different certificate for each hostname based on SNI.
This eliminates the requirement for wildcard certs where the cluster
is running on a host with multiple (typically two to three) hostnames
and the clients check the hostname against SAN in the cert
(sslmode=verify-full). Am I right? Is that feature on anybody's
roadmap?

Cheers,
Jesse

On Mon, Feb 15, 2021 at 6:09 AM Peter Eisentraut
<peter(dot)eisentraut(at)enterprisedb(dot)com> wrote:
>
> A customer asked about including Server Name Indication (SNI) into the
> SSL connection from the client, so they can use an SSL-aware proxy to
> route connections. There was a thread a few years ago where this was
> briefly discussed but no patch appeared.[0] I whipped up a quick patch
> and it did seem to do the job, so I figured I'd share it here.
>
> The question I had was whether this should be an optional behavior, or
> conversely a behavior that can be turned off, or whether it should just
> be turned on all the time.
>
> Technically, it seems pretty harmless. It adds another field to the TLS
> handshake, and if the server is not interested in it, it just gets ignored.
>
> The Wikipedia page[1] discusses some privacy concerns in the context of
> web browsing, but it seems there is no principled solution to those.
> The relevant RFC[2] "recommends" that SNI is used for all applicable TLS
> connections.
>
>
> [0]:
> https://www.postgresql.org/message-id/flat/CAPPwrB_tsOw8MtVaA_DFyOFRY2ohNdvMnLoA_JRr3yB67Rggmg%40mail.gmail.com
> [1]: https://en.wikipedia.org/wiki/Server_Name_Indication
> [2]: https://tools.ietf.org/html/rfc6066#section-3