Re: Tproxy4+squid: ebtables wiki

Dan <dan@xxxxxxxx> · Thu, 29 Oct 2009 11:24:52 -0500

Those are the same ebtable and iptable rules that I am using except that 
I use DROP.  If it is working for you then that is great. :) As for why 
it works that way I don't know.  When I use ACCEPT the traffic is 
bridged through and not redirected to squid.

Dan

Marko Kotar wrote:
Ok
My ebtable rules are(without -i option):
ebtables -t broute -A BROUTING -p ipv4 --ip-proto tcp --ip-dport 80 -j redirect --redirect-target ACCEPT

 ebtables -t broute -A BROUTING -p ipv4 --ip-proto tcp --ip-sport 80 -j redirect --redirect-target ACCEPT

This might be the different:
Bridge is up and it is having an ip address. Ethernet interfaces are up but not having any ip address asigned.
ifconfig eth0 up promisc
...
bridge interface is configured with dhclient:
dhclient3 br0

This rules are for the routing;
ip rule add fwmark 1 lookup 100
ip route add local 0.0.0.0/0 dev lo table 100
And:
echo 0 > /proc/sys/net/ipv4/conf/lo/rp_filter
echo 1 > /proc/sys/net/ipv4/ip_forward

iptables are:
iptables -t mangle -N DIVERT
iptables -t mangle -A DIVERT -j MARK --set-mark 1
iptables -t mangle -A DIVERT -j ACCEPT
iptables -t mangle -A PREROUTING -p tcp -m socket -j DIVERT
iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY --tproxy-mark 0x1/0x1 --on-port 3129

squid configuration is default, except
acl allow all
and port is set to the same address as in iptables, and having TPROXY set.
I am using: 2.6.28-16-server x86_64 ubuntu, default or compiled ebtables v2.0.9-1 (June 2009), compiled iptables v1.4.5,
Squid Cache: Version 3.1.0.14
configure options:  '--enable-linux-netfilter' --with-squid=/home/marko/src/squid-3.1.0.14 --enable-ltdl-convenience
configured ony with additional linux-netfilter flag

I've used various network configurations:
-virtual computer using VmBox with virtual interface in the linux bridge on guest pc.
-computer with two interfaces.
-double bridged vmbox: two virtual machines: first having 2 virtual interfaces. 
birdged and having sqiud. second virtual pc being client with one virtual interface. one interface of first was bridged on guest computer to external interface, other two were bridged together.

Drop didn't work in any of them, accept was tested only in first.

i think thats all the settings i have.

--- On Wed, 10/28/09, Dan <dan@xxxxxxxx> wrote:

From: Dan <dan@xxxxxxxx>
Subject: Re:  Tproxy4+squid: ebtables wiki
To: "Marko Kotar" <kotarmarko@xxxxxxxxx>, squid-users@xxxxxxxxxxxxxxx
Date: Wednesday, October 28, 2009, 9:21 PM
Marko Kotar wrote:

Thanks.

"redirect

The redirect target will change the MAC target address

to that of the bridge device the frame arrived on. This
target can only be used in the BROUTING chain of the broute
table and the PREROUTING chain of the nat table. In the
BROUTING chain, the MAC address of the bridge port is used
as destination address, in the PREROUTING chain, the MAC
address of the bridge is used.

--redirect-target target

     Specifies the standard target.

After doing the MAC redirect, the rule still has to give a
standard target so ebtables knows what to do. The default
target is ACCEPT. Making it CONTINUE could let you use
multiple target extensions on the same frame. Making it DROP
in the BROUTING chain will let the frames be routed. RETURN
is also allowed. Note that using RETURN in a base chain is
not allowed." 

I think: If accept is used it goes in the tproxy

because dst mac is changed to bridge address. (So it goes up
as it would if client had  gateway configured to that
machine?) But is also should drop work? 

I decided to test it. I changed my rule to ACCEPT and
traffic passes but not through the proxy.  My
access.log shows no new traffic after changing the
rule.  DROP is what passes the frame off to
iptables.  Could you show all your rules?  If
squid is receiving the traffic the only thing I can think of
is that maybe there is another rule further down the chain
that cause the frame to be routed.

I have tryed drop but it didn't work. I didn't get

through any traffic.

If i didn't use any of ebtable rules it went through.
But accept works.  --- On Wed, 10/28/09, Dan

<dan@xxxxxxxx>
wrote:

From: Dan <dan@xxxxxxxx>
Subject: Re:  Tproxy4+squid: ebtables

wiki

To: "Marko Kotar" <kotarmarko@xxxxxxxxx>
Cc: squid-users@xxxxxxxxxxxxxxx
Date: Wednesday, October 28, 2009, 1:03 AM
Marko Kotar wrote:

Hi,
You have incorrect commands in squid wiki for

tproxy4

ebtables:

I figure out that it is not "--redirect-target

DROP"

but it is  "--redirect-target ACCEPT" .

With ebtables using broute ACCEPT and DROP have

special

meanings.  DROP means route the frame and

ACCEPT means bridge the frame.

http://ebtables.sourceforge.net/misc/ebtables-man.html

There is a "-j REDIRECT" which should be in

lowercase

letters "-j redirect".

Thanks for guide.

Marko

Dan