Hey Henry,

I want to emulate the setup to understand the complication with a FULL linux 
based setup here on my local testing grounds.
Can you give more details on the networks in the form of subnets and VLAN 
numbers?
What is not clear to me is: Who is doing the DNAT?
Also, if you have not used tproxy and intercept on the PROXY machine you should 
re-think the whole logic of the system first before deciding on the next step.
There are systems which needs redesign when moving from Squid 2 to 3 or 4.
When I and you will have the right understanding of the scenario I believe we 
can find the right path if this is not already there.

Let me know if these( the diagrams..):
http://wiki.squid-cache.org/EliezerCroitoru/Drafts/MwanLB#Intoduction_to_MultiWAN_LoadBalancing
http://wiki.squid-cache.org/ConfigExamples/UbuntuTproxy4Wccp2

Make any sense to you so we can find the right words to fill the gaps in the 
situation.
Once I will have the right picture I would probably have enough information to 
draw some picture in VISIO and move forward to the Systems table.

Eliezer

----
Eliezer Croitoru
Linux System Administrator
Mobile+WhatsApp: +972-5-28704261
Email: elie...@ngtech.co.il


-----Original Message-----
From: squid-users [mailto:squid-users-boun...@lists.squid-cache.org] On Behalf 
Of Henry Paulissen
Sent: Thursday, September 29, 2016 5:40 PM
To: squid-users@lists.squid-cache.org
Subject: [squid-users] External nat'ed transparent proxy

Hi all,

In the company I work for we are currently using squid v2 proxies in 
transparent mode to intercept traffic from servers to the outside (access 
control).

The technical solution for this is roughly as follows:
[server] -> [gateway] -> [firewall]
                              |
    ----------- DNAT ---------
   v
[squid]  -> [gateway] -> [firewall] -> [internet router]

Our firewalls (who live between the vlan gateway and internet router), DNAT the 
traffic towards separate squid proxies (who are in a lvs cluster). These squid 
proxies are in their own vlan with special permissions to allow unrestricted 
port 80 outbound, etc, etc...

Because squid v2 is becoming more and more obsolete we are looking at upgrading 
it towards squid v3.

From what I read in the manuals, transparent mode is replaced by intercept (and 
tproxy) mode. But both dont seem to be fully backward complaint with the v2 
transparent mode.

The old trasparent mode allowed us to just dnat traffic towards the squid host 
without the need for the client to be aware of this. For example, the old style 
accepted 'GET / HTTP/1.1' (without full URL in the GET request and looking at 
the Host header for the destination).

The new intercept mode comes close to this behavior, but instead of remotly 
dnat, it wants us to next-hop it towards the squid proxy and redirect it 
locally. This is problematic for us as firewall and squid proxy dont live in 
the same vlan, so next-hop should be the router to that vlan (and forgetting 
about the path back to the server). Secondly, and not less blocking, we use 
vservers (predecessor to linux containers
lxc) as such, we dont have any promiscuous interfaces rights within the 
container.


Is there still a option to emulate normal 'regularĀ“ style squid (as without any 
listen options) but instead accepting the URI path in the GET request and 
looking at the Host header for the destination? (lets call it passthrough 
mode?).

Or, is there in squid3 a new and better way to facilitate larger setups, with 
the knowledge the server, firewall and squids are all in different vlans (and 
no, we dont have Cisco firewalls in between them ;-)).


Thanks in advance,

--
Henry Paulissen - PD0OM
he...@nitronetworks.nl - Phone: +31-(0)6-115.305.64 Linux/Unix System Engineer


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