[squid-users] SSL Bump Failures with Google and Wikipedia
Rafael Akchurin
rafael.akchurin at diladele.com
Sat Sep 30 22:16:07 UTC 2017
Hello Jeff,
Do not forget Google and YouTube are now using brotli encoding extensively, not only gzip.
Best regards,
Rafael Akchurin
> Op 30 sep. 2017 om 23:49 heeft Jeffrey Merkey <jeffmerkey at gmail.com> het volgende geschreven:
>
>> On 9/30/17, Eliezer Croitoru <eliezer at ngtech.co.il> wrote:
>> Hey Jeffrey,
>>
>> What happens when you disable the next icap service this way:
>> icap_service service_avi_resp respmod_precache
>> icap://127.0.0.1:1344/cherokee bypass=0
>> adaptation_access service_avi_resp deny all
>>
>> Is it still the same?
>> What I suspect is that the requests are defined to accept gzip compressed
>> objects and the icap service is not "gnuzip" them which results in what you
>> see.
>>
>> To make sure that squid is not at fault here try to disable both icap
>> services and then add then one at a time and see which of this triangle is
>> giving you trouble.
>> I enhanced an ICAP library which is written in GoLang at:
>> https://github.com/elico/icap
>>
>> And I have couple examples on how to work with http requests and responses
>> at:
>> https://github.com/andybalholm/redwood/
>> https://github.com/andybalholm/redwood/search?utf8=%E2%9C%93&q=gzip&type=
>>
>> Let me know if you need help finding out the issue.
>>
>> All The Bests,
>> Eliezer
>>
>> ----
>> Eliezer Croitoru
>> Linux System Administrator
>> Mobile: +972-5-28704261
>> Email: eliezer at ngtech.co.il
>>
>>
>>
>> -----Original Message-----
>> From: squid-users [mailto:squid-users-bounces at lists.squid-cache.org] On
>> Behalf Of Jeffrey Merkey
>> Sent: Saturday, September 30, 2017 23:28
>> To: squid-users <squid-users at lists.squid-cache.org>
>> Subject: [squid-users] SSL Bump Failures with Google and Wikipedia
>>
>> Hello All,
>>
>> I have been working with the squid server and icap and I have been
>> running into problems with content cached from google and wikipedia.
>> Some sites using https, such as Centos.org work perfectly with ssl
>> bumping and I get the decrypted content as html and it's readable.
>> Other sites, such as google and wikipedia return what looks like
>> encrypted traffic, or perhaps mime encoded data, I am not sure which.
>>
>> Are there cases where squid will default to direct mode and not
>> decrypt the traffic? I am using the latest squid server 3.5.27. I
>> really would like to get this working with google and wikipedia. I
>> reviewed the page source code from the browser viewer and it looks
>> nothing like the data I am getting via the icap server.
>>
>> Any assistance would be greatly appreciated.
>>
>> The config I am using is:
>>
>> #
>> # Recommended minimum configuration:
>> #
>>
>> # Example rule allowing access from your local networks.
>> # Adapt to list your (internal) IP networks from where browsing
>> # should be allowed
>>
>> acl localnet src 127.0.0.1
>> acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
>> acl localnet src 172.16.0.0/12 # RFC1918 possible internal network
>> acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
>> acl localnet src fc00::/7 # RFC 4193 local private network range
>> acl localnet src fe80::/10 # RFC 4291 link-local (directly
>> plugged) machines
>>
>> acl SSL_ports port 443
>> acl Safe_ports port 80 # http
>> acl Safe_ports port 21 # ftp
>> acl Safe_ports port 443 # https
>> acl Safe_ports port 70 # gopher
>> acl Safe_ports port 210 # wais
>> acl Safe_ports port 1025-65535 # unregistered ports
>> acl Safe_ports port 280 # http-mgmt
>> acl Safe_ports port 488 # gss-http
>> acl Safe_ports port 591 # filemaker
>> acl Safe_ports port 777 # multiling http
>> acl CONNECT method CONNECT
>>
>> #
>> # Recommended minimum Access Permission configuration:
>> #
>> # Deny requests to certain unsafe ports
>> http_access deny !Safe_ports
>>
>> # Deny CONNECT to other than secure SSL ports
>> http_access deny CONNECT !SSL_ports
>>
>> # Only allow cachemgr access from localhost
>> http_access allow localhost manager
>> http_access deny manager
>>
>> # We strongly recommend the following be uncommented to protect innocent
>> # web applications running on the proxy server who think the only
>> # one who can access services on "localhost" is a local user
>> #http_access deny to_localhost
>>
>> #
>> # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
>> #
>>
>> # Example rule allowing access from your local networks.
>> # Adapt localnet in the ACL section to list your (internal) IP networks
>> # from where browsing should be allowed
>> http_access allow localnet
>> http_access allow localhost
>>
>> # And finally deny all other access to this proxy
>> http_access deny all
>>
>> # Squid normally listens to port 3128
>> #http_port 3128
>>
>> # Uncomment and adjust the following to add a disk cache directory.
>> #cache_dir ufs /usr/local/squid/var/cache/squid 100 16 256
>>
>> # Leave coredumps in the first cache dir
>> coredump_dir /usr/local/squid/var/cache/squid
>>
>> #
>> # Add any of your own refresh_pattern entries above these.
>> #
>> refresh_pattern ^ftp: 1440 20% 10080
>> refresh_pattern ^gopher: 1440 0% 1440
>> refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
>> refresh_pattern . 0 20% 4320
>>
>> http_port 3128 ssl-bump generate-host-certificates=on
>> dynamic_cert_mem_cache_size=4MB cert=/etc/squid/ssl_cert/myCA.pem
>> http_port 3129
>>
>> # SSL Bump Config
>> always_direct allow all
>> ssl_bump server-first all
>> sslproxy_cert_error deny all
>> sslproxy_flags DONT_VERIFY_PEER
>> sslcrtd_program /usr/local/squid/libexec/ssl_crtd -s /var/lib/ssl_db
>> -M 4MB sslcrtd_children 8 startup=1 idle=1
>>
>> # For squid 3.5.x
>> #sslcrtd_program /usr/local/squid/libexec/ssl_crtd -s /var/lib/ssl_db -M
>> 4MB
>>
>> # For squid 4.x
>> # sslcrtd_program /usr/local/squid/libexec/security_file_certgen -s
>> /var/lib/ssl_db -M 4MB
>>
>> icap_enable on
>> icap_send_client_ip on
>> icap_send_client_username on
>> icap_client_username_header X-Authenticated-User
>> icap_preview_enable on
>> icap_preview_size 1024
>> icap_service service_avi_req reqmod_precache icap://127.0.0.1:1344/request
>> bypass=1
>> adaptation_access service_avi_req allow all
>>
>> icap_service service_avi_resp respmod_precache
>> icap://127.0.0.1:1344/cherokee bypass=0
>> adaptation_access service_avi_resp allow all
>>
>> Jeff
>> _______________________________________________
>> squid-users mailing list
>> squid-users at lists.squid-cache.org
>> http://lists.squid-cache.org/listinfo/squid-users
>>
>>
>
> Eliezer,
>
> Well, you certainly hit the nail on the head. I added the following
> code to check the content being sent to the icap server from squid,
> and here is what I found when I check the headers being sent from the
> remote web server:
>
> Code to check for content type and encoding received by the icap
> server added to c-icap:
>
> hdrs = ci_http_response_headers(req);
> content_type = ci_headers_value(hdrs, "Content-Type");
> if (content_type)
> ci_debug_printf(1,"srv_cherokee: content-type: %s\n",
> content_type);
>
> content_encoding = ci_headers_value(hdrs, "Content-Encoding");
> if (content_encoding)
> ci_debug_printf(1,"srv_cherokee: content-encoding: %s\n",
> content_encoding);
>
> And the output from scanned pages sent over from squid:
>
> srv_cherokee: init request 0x7f3dbc008eb0
> pool hits:1 allocations: 1
> Allocating from objects pool object 5
> pool hits:1 allocations: 1
> Geting buffer from pool 4096:1
> Requested service: cherokee
> Read preview data if there are and process request
> srv_cherokee: content-type: text/html; charset=utf-8
> srv_cherokee: content-encoding: gzip <-- As you stated, I am
> getting gzipped data
> srv_cherokee: we expect to read :-1 body data
> Allow 204...
> Preview handler return allow 204 response
> srv_cherokee: release request 0x7f3dbc008eb0
> Store buffer to long pool 4096:1
> Storing to objects pool object 5
> Log request to access log file /var/log/i-cap_access.log
>
>
> Wikipedia at https://en.wikipedia.org/wiki/HTTP_compression describes
> the process as:
>
> " ...
> Compression scheme negotiation[edit]
> In most cases, excluding the SDCH, the negotiation is done in two
> steps, described in
> RFC 2616:
>
> 1. The web client advertises which compression schemes it supports
> by including a list
> of tokens in the HTTP request. For Content-Encoding, the list in a
> field called Accept -
> Encoding; for Transfer-Encoding, the field is called TE.
>
> GET /encrypted-area HTTP/1.1
> Host: www.example.com
> Accept-Encoding: gzip, deflate
>
> 2. If the server supports one or more compression schemes, the
> outgoing data may be
> compressed by one or more methods supported by both parties. If
> this is the case, the
> server will add a Content-Encoding or Transfer-Encoding field in
> the HTTP response with
> the used schemes, separated by commas.
>
> HTTP/1.1 200 OK
> Date: mon, 26 June 2016 22:38:34 GMT
> Server: Apache/1.3.3.7 (Unix) (Red-Hat/Linux)
> Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
> Accept-Ranges: bytes
> Content-Length: 438
> Connection: close
> Content-Type: text/html; charset=UTF-8
> Content-Encoding: gzip
>
> The web server is by no means obligated to use any compression method – this
> depends on the internal settings of the web server and also may
> depend on the internal
> architecture of the website in question.
>
> In case of SDCH a dictionary negotiation is also required, which
> may involve additional
> steps, like downloading a proper dictionary from .
> .."
>
>
> So, it looks like it is a feature of the browser. So, is it possible
> to have squid gunzip the data or configure the browser not to send the
> header to remove "Accept-Encoding: gzip, deflate" from the request
> sent to the remote server telling it to gzip the data?
>
> Thanks
>
> Jeff
> _______________________________________________
> squid-users mailing list
> squid-users at lists.squid-cache.org
> http://lists.squid-cache.org/listinfo/squid-users
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