On 04/19/2012 01:58 PM, Ed W wrote:
> Hi, my dhcp configuration seems to be somewhat off
> 
> 1) I don't put dhcp on any interface, however, there is no problem 
> starting dhcp client on my net interfaces eth0, eth1
> 2) shorewall isn't "started" on eth0 because it detected there was no IP
> 3) When I plug in the network cable I guess netfilter isn't fully 
> limiting eth0?

No it isn't. There is no difference in the filter rules for an optional
interface when it is down as opposed to up.

> 4) At some point during the interface coming up, one stray packet from 
> dhcp port 67, to my net ip port=68 arrives, this is then forwarded and 
> appears to try and exit via the next entry in my default routing table 
> (the route makes sense, but not why the packet is being forwarded when 
> it's destination is the eth0 ip ?)

Sounds like the 'local' routing table hasn't been updated yet by the
DHCP client.

> 5) Once the interface is up, my scripts start "shorewall enable eth0" 
> and at this point I can't repro the effect from outside using netcat...
> 
> 
> I'm kind of stumped on the details here.  How should I configure 
> shorewall so that it does restrict this interface listed as optional, 
> which is down at shorewall start?

There is currently no way to do that. Optional interfaces were created
to allow multiple uplinks where a program like LSM can bring the links
up and down, based on the ability to pass traffic through the link.

> 
> Also how to block the stray packet which is bringing up my demand dial 
> ppp link?  I can see it on the forward chain, but I'm stumped figuring 
> out how I should set a rule to target that?

Do you block forwarded DHCP traffic?

> 
> Any thoughts on why my stack tries to forward this one packet (addressed 
> to the new eth0 ip)?

Again, sounds like the local routing table hasn't yet been updated.

-Tom
-- 
Tom Eastep        \ When I die, I want to go like my Grandfather who
Shoreline,         \ died peacefully in his sleep. Not screaming like
Washington, USA     \ all of the passengers in his car
http://shorewall.net \________________________________________________

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