[squid-users] TLS passthrough

Fernando Giorgetti fgiorgetti at gmail.com
Fri Sep 29 00:35:04 UTC 2023


>
> Bugs notwithstanding, none of the configuration
> sketches I shared previously will do that though.


Do you have any recommendations on how I could have it done?
When my tls client tries to reach the target through Squid, using
a "ssl_bump splice", it seems like squid is trying to reach itself in a
loop.

I have also tried including a peek first, but no luck.

Thanks again for all suggestions.

On Thu, Sep 28, 2023 at 7:23 PM Alex Rousskov <
rousskov at measurement-factory.com> wrote:

> On 2023-09-28 15:23, Fernando Giorgetti wrote:
>
> > Actually with the suggested blind passthrough, Squid would not handle
> > the TLS termination.
>
> Correct.
>
>
> > how will Squid know what the target is?
>
> In many cases, Squid can learn SNI by peeking at TLS ClientHello,
> without terminating TLS. Bugs notwithstanding, none of the configuration
> sketches I shared previously will do that though.
>
>
> HTH,
>
> Alex.
>
>
>
> > On Thu, Sep 28, 2023 at 1:02 PM Alex Rousskov wrote:
> >
> >     On 2023-09-28 11:31, Fernando Giorgetti wrote:
> >
> >      > And what should I do to let Squid use the SNI defined by the TLS
> >     client?
> >
> >     What do you want Squid to use that SNI for?
> >
> >     Alex.
> >
> >
> >      > On Thu, Sep 28, 2023 at 11:51 AM Alex Rousskov wrote:
> >      >
> >      >     On 2023-09-28 09:06, Fernando Giorgetti wrote:
> >      >      > Hi Matus, do you mean something like a DNAT (iptables)
> rule?
> >      >      > If so, I would say, it should work as well.
> >      >      >
> >      >      > But this is an environment I do not control, and I have
> >     been told
> >      >     to try
> >      >      > using an existing squid installation to proxy non-http/TLS
> >     data
> >      >     through.
> >      >      >
> >      >      > I appreciate any guidance or recommendation.
> >      >
> >      >
> >      >     Bugs notwithstanding, Squid can blindly tunnel intercepted
> >     (at TCP port
> >      >     X) TCP traffic to its intended destination:
> >      >
> >      >           https_port X intercept ssl-bump ...
> >      >           ssl_bump splice all
> >      >
> >      >
> >      >     Without interception, then Squid can only tunnel stuff inside
> >     HTTP
> >      >     CONNECT tunnels (for HTTP CONNECT requests received at TCP
> >     port Y):
> >      >
> >      >           http_port Y ssl-bump ...
> >      >           ssl_bump splice all
> >      >
> >      >
> >      >     In both cases, Squid does not care about the protocols that
> >     tunneled
> >      >     traffic is using. It could be HTTP, HTTPS, TLS, or anything
> >     else on top
> >      >     of TCP.
> >      >
> >      >     Your ACLs may differ from "all" in the above sketches, of
> course,
> >      >     but if
> >      >     traffic is not TLS, then you want an "ssl_bump splice" rule
> that
> >      >     matches
> >      >     during SslBump step1. A rule with an "all" ACLs is the
> >     simplest example
> >      >     of that.
> >      >
> >      >
> >      >     HTH,
> >      >
> >      >     Alex.
> >      >     P.S. I am getting an "Internal Server Error" when following
> >     the haproxy
> >      >     link in the original question, so I cannot map what that page
> >     says to
> >      >     the configurations above.
> >      >
> >      >
> >      >      > On Thu, Sep 28, 2023 at 3:41 AM Matus UHLAR - fantomas
> wrote:
> >      >      >
> >      >      >     On 27.09.23 16:48, Fernando Giorgetti wrote:
> >      >      >      >I would like to know if it is possible to set up
> >     Squid to
> >      >     perform
> >      >      >      >TLS passthrough to a given backend, relaying TLS
> >     encrypted
> >      >      >      >traffic to the backend, similarly to what HAProxy
> >     does below?
> >      >      >      >
> >      >      >
> >      >
> >      >
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough>
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough>>
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough>
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough
> <
> https://www.haproxy.com/documentation/aloha/latest/security/tls/encryption-strategies/#tls-passthrough
> >>>
> >      >      >      >
> >      >      >      >I have tried a few different configurations using
> >     reverse
> >      >     proxy,
> >      >      >      >or peek and splice, but I could not make it work
> without
> >      >     providing
> >      >      >      >a valid HTTP request or a CONNECT request.
> >      >      >
> >      >      >     what's the difference between TCP redirect and this?
> >      >      >
> >      >      >     --
> >      >      >     Matus UHLAR - fantomas, uhlar at fantomas.sk
> >     <mailto:uhlar at fantomas.sk>
> >      >     <mailto:uhlar at fantomas.sk <mailto:uhlar at fantomas.sk>>
> >     <mailto:uhlar at fantomas.sk <mailto:uhlar at fantomas.sk>
> >      >     <mailto:uhlar at fantomas.sk <mailto:uhlar at fantomas.sk>>>
> >      >      >     ; http://www.fantomas.sk/ <http://www.fantomas.sk/>
> >     <http://www.fantomas.sk/ <http://www.fantomas.sk/>>
> >      >     <http://www.fantomas.sk/ <http://www.fantomas.sk/>
> >     <http://www.fantomas.sk/ <http://www.fantomas.sk/>>>
> >      >      >     Warning: I wish NOT to receive e-mail advertising to
> this
> >      >     address.
> >      >      >     Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek
> >     reklamnu
> >      >     postu.
> >      >      >     Depression is merely anger without enthusiasm.
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