On 28/07/17 10:32, Lei Wen wrote:
Hi Amos,
/Squid does not support relaying decrypted https:// requests over an
insecure connection. So HTTP cache_peer connections will be refused./
Do you mean HTTPS cache_peer connections will be refused?
No, I mean un-encrypted cache_peer connections will be refused.
Encrypted peers might be used, BUT the peer cert is used for the
fake-cert generation. Usually the end user then encounters 'invalid
cert' problems. One also has to be very careful not to introduce other
MITM or downgrade vulnerabilities on the connections to those peers.
/Also, when TLS cache_peer is used Squid is unable to tell the
difference between the peer TLS server details an origin. So any
server-cert forging uses the cache_peer's server cert instead of the
origin./
I am using the same cert on every host, so it doesn't matter if it picks
the peer's cert. Besides, I have all sibling relation in this pool, only
parent will start the request for peer, right?
No, any sibling may pass the request on to any other. If the first proxy
to handle a request thinks that a peer has the response and that peer in
fact does not, it may be passed on to a third sibling, etc.
It does not matter if the certs on the proxies are identical or not. The
SSL-Bump is ideally not sending that particular cert to the clients. It
is generating a fake cert specific for each HTTPS domain being visited -
based on that domains real official cert.
To do that Squid expected to receive that origin servers cert on its
next-hop connection.
/In Squid-3.5 (and v4) explicit/forward proxy it is best not to use
cache_peer for decrypted content. The most working way for now is to
let it go 'DIRECT' and repeat the intercept at the peer./
Which directive do you mean by 'DIRECT' as a replacement of cache_peer?
"DIRECT" in caching hierarchy, means the proxy handling the request uses
DNS records to identify the origin server and goes directly to that (not
through a cache_peer).
My setup doesn't have many layers like a CARP cluster, it's just a squid
host pool, and they are all siblings with each other, no
parent/frontend/backend concept, each squid host is also a container
host, all containers on different host are doing similar job, so they
can share cache between different hosts. This is our initial idea for
this project if you know there are better hierarchy and can give me some
suggest I am really appreciate.
Okay, understood.
You might be able to get a sort-of workable situation with the following
parameters. I'd still expect a lot of annoying problems though.
cache_peer sibling.example.com sibling 3128 3130 \
ssl sslcafile=/path/to/ca.pem \
sslflags=NO_DEFAULT_CA ssloptions=NO_SSLv3
The /path/to/ca.pem should contain the public cert of the CA used to
sign the peers cert. Do this whether it is a self-signed CA or a public
Trusted CA.
[avoid the DONT_VERIFY_* settings, they are deadly].
Amos
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