[squid-users] question about squid and https connection .

[Alex Rousskov]

On 07/12/2018 02:35 PM, Eliezer Croitoru wrote:

> Every RSA key and certificate pair regardless to the origin server
> and the SSL-BUMP enabled proxy can be different.

I cannot find a reasonable interpretation of the above that would
contradict what I have said. Yes, each unique certificate has its own
private key, but that is not what Ahmad was asking about AFAICT.


> Will it be more accurate to say that just as long as these 200 squid
> instances(different squid.conf and couple other local variables) use
> the same exact ssl_db cache directory  then it's probable that they
> will use the same certificate.

That statement is incorrect. Squids configured with different CA
certificates will generate different fake certificates for the same real
certificate.

I assume that Ahmad was asking about a situation where 200 Squid
instances had the same configuration (including CA certificates).

Please note that the certificate generator helper gets the signing (CA)
certificate as a parameter with each generation request (because
different Squid ports may use different CA certificates). Also, Squid
probably does not officially support sharing the certificate directory
across Squid instances (even if it works).


> Or these 200 squid instances are in SMP mode with 200 workers... If
> these 200 instances do not share memory and certificate cache then
> there is a possibility that the same site from two different sources 
> will serve different certificates(due to the different RSA key which
> is different).

200 SMP workers or 200 identically-configured Squid instances will
generate the same fake certificates for the same real certificate.
"Stable certificates" is an important requirement for many distributed
Squid deployments.

Alex.



> -----Original Message-----
> From: squid-users [mailto:squid-users-bounces at lists.squid-cache.org] On Behalf Of Alex Rousskov
> Sent: Thursday, July 12, 2018 11:27 PM
> To: --Ahmad-- <ahmed.zaeem at netstream.ps>; Squid Users <squid-users at lists.squid-cache.org>
> Subject: Re: [squid-users] question about squid and https connection .
> 
> On 07/12/2018 01:17 PM, --Ahmad-- wrote:
> 
>> if i have pc# 1 and that pc open facebook .
>>
>> then i have other pc # 2 and that other pc open facebook .
>>
>>
>> now  as we know facebook is https .
>>
>> so is the key/ cert that used on pc # 1 is same as cert in pc # 2 to decrypt the fb encrypted traffic ?
> 
> Certificates themselves are not used (directly) to decrypt traffic
> AFAIK, but yes, both PCs will see the same server certificate (ignoring
> CDNs and other complications).
> 
> 
> 
>> now in the presence of squid .
>>
>> if i used tcp connect method  , will it be different than above ?
> 
> If you are not bumping the connection, then both PCs will see the same
> real Facebook certificate as if those PCs did not use a proxy.
> 
> If you are bumping the connection, then both PCs will see the same fake
> certificate generated by Squid.
> 
> 
> 
>> say i used 200 proxies in same squid machine and i used to access FB from the same pc same browser .
>>
>> will facebook see my cert/key i used to decrypt its traffic ?
> 
> If you are asking whether Facebook will know anything about the fake
> certificate generated by Squid for clients, then the answer is "no,
> unless Facebook runs some special client code to deliver (Squid)
> certificate back to Facebook".
> 
> In general, the origin server assumes that the client is talking to it
> directly. Clients may pin or otherwise restrict certificates that they
> trust, but after the connection is successfully established, the server
> may assume that it is talking to the client directly. A paranoid server
> may deliver special code to double check that assumption, but there are
> other, more standard methods to prevent bumping such as certificate
> pinning and certificate transparency cervices.
> 
> 
> 
>> is the key/cert of FB to decrypt the https content is same on all browsers on all computers ?
> 
> If you are asking whether the generated certificates are going to be the
> same for all clients, then the answer is "yes, provided all those 200
> Squids use the same configuration (including the CA certificate) and
> receive the same real certificate from Facebook". Squid's certificate
> generation algorithm generates the same certificate given the same
> configuration and the same origin server certificate.
> 
> 
> HTH,
> 
> Alex.
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