[squid-users] HTTPS caching is not working in squid with ssl-bump enabled

Vignesh Ramessh vigneshisvignesh at gmail.com
Wed Mar 24 10:11:01 UTC 2021

Hi Alex,

We have just started to integrate squid proxy in our project, thanks for
your reply and support.

Previously we were seeing TCP_TUNNEL for https://www.google.com.
Now, we are able to see the TCP_MISS transactions for https://www.google.com
As https://www.google.com does not contain a cache-control header in
response, the response cannot be cached which we are aware of.

1616580079.857     73 ::1 NONE/200 0 CONNECT www.google.com:443 -
1616580079.945     44 ::1 TCP_MISS/200 967 HEAD https://www.google.com/ -
HIER_DIRECT/ text/html

I generated key.pem and cert.pem files using openssl and when i tried to
connect a local python https web server which has cache-control headers in
https response, got the below error,

root at raspberrypi-rdk-hybrid:~# curl -I
--proxy-cacert cert.pem --proxy http://localhost:3128
HTTP/1.1 200 Connection established

curl: (60) SSL certificate problem: unable to get local issuer certificate
More details here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

Have attached the squid.conf file for your reference. Can you please check
and let me know if I am missing something ?


On Tue, Mar 23, 2021 at 7:44 PM Alex Rousskov <
rousskov at measurement-factory.com> wrote:

> On 3/23/21 2:10 AM, Vignesh Ramessh wrote:
> > Currently am running squid version 4.14 on RPi3.
> > Trying to cache https responses with cache-control:max-age headers
> > available,
> > using ssl bump - peek n splice feature with examples available in this
> > link :- https://elatov.github.io/2019/01/using-squid-to-proxy-ssl-sites/
>    ssl_bump peek step1
>    ssl_bump bump all
>    ssl_bump splice all
> AFAICT, the above "bump all during step2" configuration (the last line
> does not do anything and should be removed) should bump all traffic. Is
> that your configuration?
> > But the https caching doesnt seem to work, https connections are getting
> > established as TCP_TUNNEL/200 in squid access logs.
> Do you see non-CONNECT HTTP traffic (e.g. GET, POST, etc.) in access
> log? If not, then Squid is not bumping traffic OR the client does not
> like what Squid is doing. Please post your http*_port and ssl_bump
> configuration with access.log lines corresponding to a single test
> transaction that you think should be bumped.
> Also, does the client (e.g. curl, wget, or browser) get an error from
> Squid? Does the client display any kind of warning or error at all? What
> certificate does the client show for the test connection?
> > I wasnt able to find any proper documentation on https caching using
> squid.
> What you call "HTTPS caching" consists of two virtually independent
> actions: Bumping HTTPS connections and caching. Documentation exists for
> each action. Currently, it sounds like the first action (bumping) is not
> working in your setup. Until that is addressed, you can ignore the
> caching part.
> HTH,
> Alex.
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