[squid-users] HTTPS Filtering and SSL-Bump

[Marcus Kool]

On 04/23/2015 05:52 PM, Jonathan Chretien wrote:
> Hi all.
>
> I'm trying to implement the filtering of https content for a particular url. The only thing that I'm trying to do it's to unlock corporate video on the Youtube website. I do not want to unlock everything on Youtube but only our corporate stuff.
>
> The url looks like this: https://www.youtube.com/users/MyCompany.
>
> I'm using UFDBGuard as a url filter.
>
> The problem is that SSL-Bump is working well but the URL pass from Squid to UFDBGuard is the non SSL-Bump url. What I means is that the URL that UFDBGuard is receiving is https://www.youtube.com:443 instead of the https://www.youtube.com/users/MyCompany.
>
> So because UFDBGuard is not receiving the complete SSL-Bump URL, UFDBGuard see that it's Youtube.com, so it block the website. If UFDBGuard was receiving the real SSL-Bump url https://www.youtube.com/users/MyCompany, UFDBGuard will see that this url is whitelisted and should allow the access.


This is not the full story.
With SSLbump on Squid sends to ufdbGuard first
    CONNECT www.youtube.com:443
and then
    GET  https://www.youtube.com/users/MyCompany

ufdbGuard has not yet support for this but you could whitelist
    www.youtube.com:443
using a regular expression
and whitelist https://www.youtube.com/users/MyCompany and a bunch of other URLs that used for the markup of the entire page
and blacklist a bunch of other youtube URLs to get the desired behavior.

Whitelisting a subset of a website is usually not so straightforward so one needs to pay much attention to the "bunch of URLs" used in the whitelist and blacklist.
I suggest to not blacklist www.youtube.com but start with blacklisting a few important URLs of youtube such that the effective result is that non-company access to Youtube is blocked.

Marcus
maintainer of ufdbGuard.

PS: after you have done all this, you also need to block all web proxies which can be used to circumvent the intended Youtube block.


> Log in the UFDBGuard.log
> 2015-04-23 16:19:59 [10669] BLOCK MyUser   192.168.100.27       Internet   movies    www.youtube.com:443 CONNECT
>
> Is there something missing in my Squid.conf to pass the correct URL?
>
> http_port 192.168.100.2:3129 ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=4MB key=/etc/squid/ssl/mycert.com.private cert=/etc/squid/ssl/mycert.com.cert
>
> # SSL Bump Config
> sslproxy_cert_error deny all
> sslproxy_flags DONT_VERIFY_PEER
> sslcrtd_program /usr/lib64/squid/ssl_crtd -s /var/lib/ssl_db -M 4MB sslcrtd_children 8 startup=1 idle=1
>
> acl sslBumpYoutube dstdomain www.youtube.com
>
> # SSL Bump Config
> always_direct allow sslBumpYoutube
> ssl_bump server-first sslBumpYoutube
> ssl_bump none all
>
> Also all my users using the proxy are authenticated.
>
>
> Thanks
> ___________________________________
> Jonathan
>
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