On 11/12/2015 07:03 AM, Edouard Gaulué wrote:
Hi Marcus, Amos and maybe others,
Here were I am. I've looked in the log. Let me describe what I observe. It's
maybe linked with some other posts I've read.
Imagine I try to connect to http://ad.doubleclick.net/ad.jpg. I observe the
request in wireshark. It goes to the squid process: there is no SSL involved so
no bump. Squidguard sends its redirect to
squid and Squid sends to the browser :
HTTP/1.1 302 Found
Server: squid/3.5.10
Date: Wed, 11 Nov 2015 22:49:44 GMT
Content-Length: 0
Location:
https://proxyweb.xxx.xxx/cgi-bin/squidGuard-simple.cgi?clientaddr=xxx&clientgroup=low-ip&targetgroup=adv&url=http://ad.doubleclick.net/ad.jpg
X-Cache: MISS from squid
X-Cache-Lookup: MISS from squid:3128
Via: 1.1 squid (squid/3.5.10)
Connection: keep-alive
The browser next sends a request to proxyweb: everything is fine.
Now let's add some SSL stuff and connect to https://ad.doubleclick.net/ad.jpg.
I observe the request in wireshark. It goes to the squid process with SSL.
Squidguard sends its redirect to squid and
Squid sends to the browser :
HTTP/1.1 302 Found
Server: squid/3.5.10
Date: Wed, 11 Nov 2015 22:49:44 GMT
Content-Length: 0
Location:
https://proxyweb.xxx.xxx/cgi-bin/squidGuard-simple.cgi?clientaddr=xxx&clientgroup=low-ip&targetgroup=adv&url=http://ad.doubleclick.net/ad.jpg
X-Cache: MISS from squid
The browser next tries to send a direct request to https://ad.doubleclick.net
that is never ending as this machine hasn't got the right to go on the Internet.
This is the strange part! Why would the browser connect to ad.doubleclick.net
if SG redirected the request to proxyweb.xxx.xxx ?
I think you need to increase debug levels of Squid and show the fragments of
cache.log where Squid receives the redirection from SG and what happens next.
Why is the REDIRECT not the same with and without SSL? It looks it disturbs the
navigator (at least Mozilla and IE).
SSL is a protocol designed not to be tampered with. The SSL protocol has no
support for redirection so any redirection by Squid or an other proxy is an
attempt to break the SSL protocol.
Redirection with HTTP is simple because the HTTP protocol has a built-in
mechanism for redirection that proxies can use.
Marcus
I can also provide squid logs, but tell me what because I've got a lot...
Regards, EG
Le 05/11/2015 14:01, Marcus Kool a écrit :
On 11/04/2015 08:55 PM, Edouard Gaulué wrote:
Hi Marcus,
Well that just an URL rewriter program. You can just test it from the command
line :
echo "URL" | /usr/bin/squidGuard -c /etc/squidguard/squidGuard.conf
Before I understood it was possible to precise the redirect code I got that:
#> echo
"https://ad.doubleclick.net/N4061/adi/com.ythome/_default;sz=970x250;tile=1;ssl=1;dc_yt=1;kbsg=HPFR151103;kga=-1;kgg=-1;klg=fr;kmyd=ad_creative_1;ytexp=9406852,9408210,9408502,9417689,9419444,9419802,9420440,9420473,9421645,9421711,9422141,9422865,9423510,9423563,9423789;ord=968558538238386?
- - GET"|/usr/bin/squidGuard -c /etc/squidguard/squidGuard.conf
#> OK
rewrite-url="https://proxyweb.XXXXX.XXXXX/cgi-bin/squidGuard-simple.cgi?clientaddr=-pipo&clientname=&clientuser=&clientgroup=default&targetgroup=unknown&url=https://ad.doubleclick.net/N4061/adi/com.ythome/_default;sz=970x250;tile=1;ssl=1;dc_yt=1;kbsg=HPFR151103;kga=-1;kgg=-1;klg=fr;kmyd=ad_creative_1;ytexp=9406852,9408210,9408502,9417689,9419444,9419802,9420440,9420473,9421645,9421711,9422141,9422865,9423510,9423563,9423789;ord=968558538238386?";
After a little change in the squidguard.conf, I get:
#> OK status=302
url="https://proxyweb.echoppe.lan/cgi-bin/squidGuard-simple.cgi?clientaddr=-pipo&clientname=&clientuser=&clientgroup=default&targetgroup=unknown&url=https://ad.doubleclick.net/N4061/adi/com.ythome/_default;sz=970x250;tile=1;ssl=1;dc_yt=1;kbsg=HPFR151103;kga=-1;kgg=-1;klg=fr;kmyd=ad_creative_1;ytexp=9406852,9408210,9408502,9417689,9419444,9419802,9420440,9420473,9421645,9421711,9422141,9422865,9423510,9423563,9423789;ord=968558538238386?";
This looks fine, so now you need to look at Squid and set the debug options to
find out what it is doing.
Note that squidGuard does not percent-escape the URL parameter as it should
(see RFC 3986).
This is, however, most likely not the cause of the issue that you are seeing.
Marcus
It's not so better handled by my browser saying "can't connect to
https://ad.doubleclick.net"; message. But, I don't get the squid message anymore
regarding http/https.
It may be that rewrite_rule_program come after peek and splice stuff leading
squid to an unpredictable situation. Is there a way to play on order things
happen in squid?
Regards, EG
Le 04/11/2015 14:10, Marcus Kool a écrit :
You need to know what squidGuard actually sends to Squid.
squidGuard does not have a debug option for this, so you have to set
debug_options ALL,1 61,9
in squid.conf to see what Squid receives.
I bet that what Squid receives, is what it complains about:
the URL starts with 'https://http'
Marcus
On 11/04/2015 10:55 AM, Edouard Gaulué wrote:
Le 04/11/2015 11:00, Amos Jeffries a écrit :
On 4/11/2015 12:48 p.m., Marcus Kool wrote:
I suspect that the problem is that you redirect a HTTPS-based URL to an
HTTP URL and Squid does not like that.
Marcus
To give it a try in that direction I now redirect to an https server. And I get
:
The following error was encountered while trying to retrieve the URL:
https://https/*
*Unable to determine IP address from host name "https"*
The DNS server returned:
Name Error: The domain name does not exist.
Moreover this would leads sometimes to HTTP-based URL to an HTTPS URL and I
don't know how much squid likes it either.
No it is apparently the fact that the domain name being redirected to is
"http".
As in:"http://http/something";
I can assure my rewrite_url looks like
"https://proxyweb.xxxxx.xxxxx/var1=xxxx&...";.
And this confirm ssl_bump parse this result and get the left part before the ":". To play with, I have
also redirect to "proxyweb.xxxxx.xxxxx:443/var1=xxxx&..." (ie. I removed the "https://";
and
add a
":443") to force the parsing. Then I don't get this message anymore, but
Mozilla gets crazy waiting for the ad.doubleclick.net certificate and getting the
proxyweb.xxxxx.xxxxx one. And of course it
breaks my SG configuration and can't be production solution.
Which brings up the question of why you are using SG to block adverts?
squid.conf:
acl ads dstdomain .doubleclick.net
http_access deny ads
Amos
I don't use SG to specificaly block adverts, I use it to block 90 % of the web.
Here it's just an example with ads but it could be with so much other things...
I just want to try make SG and ssl_bump live together.
Is this possible to have a rule like "if it has been rewrite then don't try to
ssl_bump"?
Regards, EG
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