[j-nsp] Firewall filter for locally generated packets

[Ian MacKinnon]

Hi all,

I am doing some work with PXE-booting of servers and using bootp helpers 
to get to the dhcp server.

All working fine so far.

However the dhcp response back to the server appears to be coming from 
the local interface directly, and our standard firewalling is dropping it.

I can open the firewall to allow all udp 67/68 packets through,but I 
would rather limit it.

Now I could add the local ip address to the rule, but have have a 
standard set of rules we apply to all interfaces, so if there is some 
way of specifying allow locally generated packets through that would be 
better.

eg
we have an interface with an ip address like 192.168.0.1/24
In syslog we see
Mar 27 16:05:41 my-router-01/my-router-01 /kernel: %FIREWALL-6-FW: 
.local..0    R  udp 192.168.0.1 255.255.255.255    67    68


ie the interface name is .local..0 and the source is 192.168.0.1


Our firewall rule then looks like :-
term permit_bootp_install {
     from {
         source-address {
             192.168.0.1/32;
         }
         protocol udp;
         destination-port [ 67 68 ];
     }
}


But rather than use the source-address what can I use for locally 
generated packets?

Thanks


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