[squid-users] SSL Bump Failures with Google and Wikipedia
Jeffrey Merkey
jeffmerkey at gmail.com
Sat Sep 30 22:22:09 UTC 2017
On 9/30/17, Rafael Akchurin <rafael.akchurin at diladele.com> wrote:
> 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
>
Resetting the browser settings to disable gzip worked. I can see the
pages now. The best way to implement this is to intercept the
accept-encoding header and either remove it or modify it from icap
before being sent to the remote server.
Jeff
More information about the squid-users
mailing list