Hello,

What does your shorewall interfaces looks like?
One question I had is which interface is the <elsewhere> zone connected to?

Maybe <elsewhere> is better suited for an entry on shorewall host file?

Cheers

 
-----------------
Leandro Avila


----- Original Message -----
From:Vieri Di Paola <[email protected]>
To:[email protected]
Cc:
Sent:Thursday, March 24, 2011 4:09 AM
Subject:Re: [Shorewall-users] shorewall bridge

Hi,

According to http://www.shorewall.net/bridge-Shorewall-perl.html:

<fw> -> <BP zone> rules are not allowed
<non-BP zone> -> <BP zone> rules are not allowed

"Policies from a non-BP zone to a BP are disallowed.
Rules where the SOURCE is a non-BP zone and the DEST is a BP zone are 
disallowed."


/etc/shorewall/zones defines a <BP zone> as a "subzone" of a <non-BP zone>:

#ZONE           TYPE            OPTIONS
fw              firewall
elsewhere       ipv4  
world           ipv4  
net:world       bport
loc:world       bport

So I'm supposing that one CANNOT define rules and policies such as:

<elsewhere> -> <loc>

but can define rules such as:

<elsewhere> -> <world>

Suppose that my loc zone is physically connected to eth0 and net is connected 
to eth1 and that I want to allow specific IP addr/port traffic from <elsewhere> 
to <net> but block it from <elsewhere> to <loc>.
If I set this in /etc/shorewall/policy:
elsewhere    world        REJECT
and this in /etc/shorewall/rules:
ACCEPT            elsewhere              world:<SMTP_SERVER_IP_ADDR>            
 tcp              25
then I should be blocking all SMTP traffic except to my SMTP server.
However, I won't be able to explicitly allow tcp 25 traffic to the "loc" 
subzone of "world" and disallow tcp 25 traffic to the "net" subzone.
Also, if the net subzone is considered "insecure" then a host in that subzone 
could assign itself the same IP address as my SMTP server thus receiving SMTP 
traffic illegitimately.

Is this a physdev match limitation?
Is there a solution to this other than making sure that my net subzone isn't 
"insecure"?

On the other hand, if my /etc/shorewall/policy file contains:
net             elsewhere             REJECT          info
net             world             REJECT          info
and a host from <elsewhere> tries to connect to <SMTP_SERVER_IP_ADDR> and the 
latter is within the net bport subzone (ie. connected to eth1 in my example) 
then it should fail, right?
The connection should succeed if <SMTP_SERVER_IP_ADDR> were connected to eth0 
(loc bport subzone).

Thanks,

Vieri


      

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