Argh
I found the error - one of my ethernet interfaces were partially
defective.. That explains why the bridge didn't know of the machine
behind the bridge itself :-)

I love this concept - I am SO thrilled, that I made it work :-)))

/Klaus


On Fri, 2002-06-21 at 14:22, Klaus Agnoletti wrote:
> Hi there,
> 
> I am trying to set up a bridging firewall on a debian woody server, so
> it can firewall certain windows servers at our ISP.
> 
> We got 32 ips or so, on one subnet, so I figured this was the right way
> to do firewalling for those.
> 
> What I've done is this :
> I pathched the kernel without any errors. I tried this both on the stock
> kernel from kernel.org and on the debian distributed
> kernel-source-2.4.18 package.
> I compiled a new kernel with both Network packet filtering support and
> support for 802.1d Ethernet bridging and netfilter firewalling support
> there.
> 
> So far so good.
> 
> With the new kernel, I have setup a testing environment with one Linux
> box behind the bridge, attached with a cross-over cable into eth1 and
> eth0 plugged into a switch with uplink to the switch that controls the
> company network.
> 
> I added these lines in /etc/network/interfaces :
> 
> iface br0 inet static
>         address 192.168.200.200
>         network 192.168.200.0
>         broadcast 192.168.200.255
>         netmask 255.255.255.0
>         gateway 192.168.200.1
>         bridge_ports all
> 
> A very simple setup, described in the docs that comes with the
> bridge-utils deb package.
> 
> I've set up two forwarding iptables rules, taken from this mailing list
> to allow forwarding between the two ethernet interfaces :
> 
> wp-fw-1:~# iptables -n -L
> Chain INPUT (policy ACCEPT)
> target     prot opt source               destination         
> 
> Chain FORWARD (policy ACCEPT)
> target     prot opt source               destination         
> ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0          
> ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0          
> 
> Chain OUTPUT (policy ACCEPT)
> target     prot opt source               destination         
> wp-fw-1:~# 
> 
> When doing a brctl showmacs br0, I can see a few macs on interface 1
> (going into the switch and the company network) and only one on
> interface 2 - which is the mac address of interface 2 on the bridge -
> _not_ the ethernet interface of the machine behind the bridge, which
> triggers me. As far as I understand it this means that the bridge
> doesn't know about that box - and thus can't forward any traffic to it.
> 
> I think this is the core of my problem.
> 
> In debian setting up the network interfaces is handled by the above
> mentioned configuration file (/etc/network/interfaces), and as far as I
> understand it isn't possible to setup the bridge without having an IP
> due to this distribuition specific thing. What I would like to do
> eventually though, is to set the bridge up without an IP. How can this
> be done in debian ?
> 
> To elminate the firewalling issues, I tried building a vanilla 2.4.18
> kernel as well, with only bridging support - and no firewalling. Same
> result.
> 
> Can anybody help ?
> 
> 
> -- 
> Med venlig hilsen / Regards
> 
> Klaus Agnoletti
> Junior Geek Engineer
> 
> Xenux - The Linux People
> Bredgade 35A, 2.
> 1260 K�benhavn K
> Tel: +45 3315 8202
> Fax: +45 3332 1832
> http://www.xenux.dk
> 
-- 
Med venlig hilsen / Regards

Klaus Agnoletti
Junior Geek Engineer

Xenux - The Linux People
Bredgade 35A, 2.
1260 K�benhavn K
Tel: +45 3315 8202
Fax: +45 3332 1832
http://www.xenux.dk

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