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Re: ssl_bump with parent cache

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Ok, with a bit more messing with it...  Changing bump to splice does work:

ssl_bump splice all

Adding:

acl step2 at_step SslBump2
ssl_bump peek step1
ssl_bump peek step2
ssl_bump splice step2

Fails (back to the connection errors as with bump).  My guess is that this means it can splice at step1 but not step 2, which I know is more intrusive. 

This appears to be the relevant data from the log:

2022/03/08 14:35:47.644 kid1| 83,7| bio.cc(163) stateChanged: FD 10 now: 0x4004 TED (TLSv1.3 early data)
2022/03/08 14:35:47.644 kid1| 83,7| bio.cc(163) stateChanged: FD 10 now: 0x2002 SSLERR (error)
2022/03/08 14:35:47.644 kid1| Error negotiating SSL connection on FD 10: error:00000001:lib(0):func(0):reason(1) (1/-1)

at which point it starts freeing memory, etc.

On Mar 8 2022, at 2:57 pm, Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
On 3/8/22 16:38, Aaron Dewell wrote:

> Hi Alex, thanks for your reply!  I did get access to the parent proxy
> and my assumption was wrong, it's doing minimal bumping.

TLS inspection at the parent proxy does not affect what I was trying to
double check. What matters is whether it is a forward HTTP proxy (e.g.,
a Squid instance listening on an http_port configured without intercept,
tproxy, or accel flags). It sounds like that is what it is. That's OK!

I do not remember whether your Squid version (v4.13) supports SslBump
with parent forward proxies, but I believe modern Squids do, and we can
assume that your Squid version does as well. The debugging should show
whether that is indeed the case.


> The parent is doing peek and splice to an exact list of internal
> destinations.  Specifically, peek step1 all, peek step2 allowed_sites,
> splice allowed_sites, terminate all.  That shouldn't (to my imperfect
> knowledge) interfere with what I'm doing though.

Yes, assuming the parent does not terminate your Squid connections, of
course (i.e. assuming connections from your Squid always match
allowed_sites after step1 at the parent proxy).


> That's a good idea to do splice only and see if that's successful.
> Trying to do too much at once!  I'll see what that does, then try debug
> again.  The debug output wasn't very helpful before, but stepwise may be
> more useful.

Just to clarify: The debugging output was not meant for you to
interpret. A Squid developer should do that. It may contain sensitive
details; it is best to not use anything but test traffic and test
certificate keys when sharing ALL,9 output.

Alex.


> On Mar 8 2022, at 1:43 pm, Alex Rousskov wrote:
>
> On 3/8/22 14:16, Aaron Dewell wrote:
>
> > I'm trying to use these two features at the same time.  The use
> case is
> > pretty simple.  I want to capture all traffic from a single source (a
> > device of mine) to another squid proxy server and decrypt/log
> it.    I'm
> > using the Ubuntu 20 package of squid-ssl version 4.13.
> >
> > Device -> ssl_bump proxy -> upstream proxy -> website
> >
> > It was all successfully working without ssl_bump, so the cache_peer
> > configuration works.  One side note: the parent proxy is running
> on 443
> > without SSL (I believe - I don't run it but I've asked those that
> do for
> > confirmation, but I do know it's a pretty standard destination proxy
> > configuration).
> >
> > The website itself is not directly accessible thus the upstream
> proxy is
> > required.
> >
> > Adding the ssl_bump configuration caused it to not work, with errors
> > about SSL versions and "Error negotiating SSL connection on FD
> xx".  My
> > best guess is that it is attempting to establish an SSL connection to
> > the upstream and failing.
> >
> > acl step1 at_step SslBump1
> > ssl_bump peek step1
> > ssl_bump bump all
> > http_port 3128 ssl-bump cert=/var/lib/squid/ssl_cert/myCA.pem
> > generate-host-certificates=on dynamic_cert_mem_cache_size=4MB
> > tls_outgoing_options options=NO_SSLv3
> > flags=DON'T_VERIFY_PEER,DONT_VERIFY_DOMAIN
> > cert=/var/lib/squid/ssl_cert/device.pem
> > key=/var/lib/squid/ssl_cert/client.key
> >
> > (client.key and client.pem are from the device and are needed due
> to the
> > authentication of the session at the destination server.  Also, I
> > haven't looked at the packet logging yet. I assume that will be
> an easy
> > addition once the setup works generally.)
> >
> > However, my understanding is that the cache_peer configuration should
> > NOT do TLS by default unless that was specified in the options, and I
> > see no way to explicitly disable it.
> >
> > So first question: is that assumption accurate?  No TLS to the parent
> > unless explicitly configured?
>
> Yes, that is correct: cache_peers are plain HTTP forward proxies unless
> explicitly configured otherwise. Their listening port value does carry
> any special meaning as far as Squid code is concerned.
>
> However, it is very unusual to run a plain HTTP forward proxy on port
> 443. That port may imply that your parent proxy is an HTTPS reverse
> proxy. If it is, you need to use originserver flag when configuring the
> corresponding cache_peer line. You can check by sending plain CONNECT
> requests to that upstream proxy using wget, curl, or some such. A
> reverse HTTPS proxy would reject such requests.
>
>
> > if the ssl_bump configuration is causing it to attempt an upstream
> > TLS connection ...
>
> Bugs notwithstanding, it should not.
>
>
> > Anything here that I'm doing obviously wrong?
>
> I see no red flags relevant to your specific question.
>
> Does replacing "bump all" with "splice all" fix the problem? I realize
> that you do want to bump/see the device traffic, but I wonder whether
> the errors are not between Squid and the upstream proxy but Squid and
> the web site. Splicing would remove those errors while still keeping
> some SslBump code active.
>
> Sharing a (pointer to compressed) libpcap packet capture and/or a
> (pointer to compressed) ALL,9 cache.log while reproducing the problem
> with a single transaction may help:
> https://wiki.squid-cache.org/SquidFaq/BugReporting#Debugging_a_single_transaction
>
> Alex.
> _______________________________________________
> squid-users mailing list
> squid-users@xxxxxxxxxxxxxxxxxxxxx
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>
> Sent from Mailspring
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