Thanks for the reply, Tom. Your critique of this routed Xen network has
shown me the fatal error in my thinking:

> So eth7 has IP address 196.168.2.169. From The routing table:
> 
> 192.168.192.252 dev eth7  scope link  src 192.168.2.169
> 
> So apparently, you have a VM with IP address 192.168.192.252 running on 
> the VM associated with VIF eth7. Is that correct?

I assumed (from previous standalone Bering firewalls) that the DMZ needs
to be on its own subnet. Hence I have Dom0's eth0 (192.168.2.169) in the
loc zone and eth7 (192.168.192.252) associated with DomU in the dmz
zone. Because Xen configures eth7 to have the same address as eth0 my
configuration is wrong. 

eth7 should have an address in the same subnet (192.168.2.0) as eth0,
right? Yet, having the loc and dmz zones on the same subnet seems
counter intuitive and insecure...

> Your /etc/shorewall/masq file makes no sense: It appears to look like:
> 
> eth2  192.168.2.0/24  
> eth2  192.168.2.11    
> eth2  192.168.2.12
> eth2  192.168.2.18    62.24.195.87
> 
> a) All but the first rule are useless since they are masked by the first 
> rule (remember that the first match determines the outcome except in the 
> tcrules file).

So, the first rule will be sufficient if eth7 has an address in the
192.168.2.0 subnet.

> b) You are not masquerading/SNATting 192.168.192.252.
> 
> I see that you have a couple of DNAT rules:
> 
>      0     0 DNAT       tcp  --  *      *       0.0.0.0/0 
> 192.168.1.27        tcp dpt:18080 to:192.168.192.252:80
>      0     0 DNAT       tcp  --  *      *       0.0.0.0/0 
> 192.168.1.27        tcp dpt:22252 to:192.168.192.252:22

I will update these DNAT rules with eth7's new IP address.

> I don't think there is anything correct about this IP configuration.

The truth hurts!

Thanks for your honest appraisal of my network. I based my configuration
on your routed Dom0 example at
http://www.shorewall.net/XenMyWay-Routed.html but got confused by the
fact that you have multiple public IP addresses associated with various
physical and virtual interfaces. The paradigm shift to Xen networking is
not trivial and your help is greatly appreciated.

Werner


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