Shawn Wright wrote:
> Hello,

Hello Shawn.

Haven't heard from you in quite a while.

> 
> We are using several DNAT rules for incoming traffic to our network, and 
> several 
> more MASQ rules for outgoing traffic. Now, I have a request for a mechanical 
> controls system which needs a DNAT for a single UDP port, but also needs a 
> MASQ rule for accessing web traffic. The machine will be a private IP inside 
> our 
> LAN, routed by our Cisco router to the firewall running shorewall. 
> 
> ie:
> 
> I have this in rules:
> 
> DNAT   net     sls:10.2.251.10:21068   udp     21068   -    x.x.x.x 
> (x.x.x.x = firewall eth1 address)

So let's see if I understand the problem.

You want to:

a) Forward UDP port 21068 to 10.2.251.10; and
b) You want to masquerade 10.2.241.10 to the internet.

If that's correct, then we need to know:

a) Does the Shorewall box have a route to 10.2.243.10 via the Cicso?
b) Is the Cisco doing any form of NAT on behalf of 10.2.251.10?

I assume that the firewall has a route via the Cisco for the 10.2.254.10/xx
network?

> 
> and this in masq:
> eth1    $VLAN251        64.251.72.14
> 
> I'm guessing this won't work.

Without knowing what the contents of $VLAN251 are, we have no way of telling.

Is there another way to achieve this without adding
> another external IP to the firewall?

If the Shorewall box has a route to 10.2.254.10 via the cisco and $VLAN251
includes 10.2.254.10, and if 10.2.254.10 has a default route through the
cisco and if the cisco has a default route through the Shorewalll box then
it should work with the rules that you have.

I suggest that you read http://www.shorewall.net/Multiple_Zones.html since
it covers your network topology.

> 
> shorewall version 2.2.0 (I know, it's old)

Old! That ancient thing went out of support between Thanksgiving day and
Christmas in 2005! Given that is the case, I don't know how much help we (or
the current Shorewall documents) will be.

> two nics as follows:
> 
> eth1 (net) <-> [fw] <-> eth0 (int) <-> [Cisco] <-> local 10.x.x.x subnets
> 
> both eth1 and eth0 are on public routable networks, everything behind the 
> Cisco 
> is private. 

-Tom
-- 
Tom Eastep    \ Nothing is foolproof to a sufficiently talented fool
Shoreline,     \ http://shorewall.net
Washington USA  \ [EMAIL PROTECTED]
PGP Public Key   \ https://lists.shorewall.net/teastep.pgp.key

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