[speirsfr]

Hi,

I've been trying to get my Mac OS X Server (10) box to route stuff from my home LAN to the internet.

I figured out the options in gNAT OK, but I was more confused about the configuration of my 2 ethernet cards in the Network preferences.

I created a DHCP configuration for the built in ethernet (en0 - connected to my cable modem). That seemed to work OK, but when I create a second, manually specified IP address (192.168.0.1) for en1, I don't understand how the system decides which port to use when I'm sitting at the server box trying to use the internet.

I know in the advanced popup you can select a priority for ports, but if I'm sending data to the 192.168.0.0 network, and en1 is the second-choice interface after en0, do I need to wait for the process to somehow 'fail' to send on en0 before it will try en1?

I followed the instructions on osxfaq.com, but they weren't explicitly for Server, so I'm wondering if the IPFilter service in MOSXS changes the ipfw/nat landscape somehow?

Ideas?

Thanks,
Fraser

[geekstud]

Originally posted by speirsfr:
<STRONG>Hi,

I've been trying to get my Mac OS X Server (10) box to route stuff from my home LAN to the internet.

I figured out the options in gNAT OK, but I was more confused about the configuration of my 2 ethernet cards in the Network preferences.

I created a DHCP configuration for the built in ethernet (en0 - connected to my cable modem). That seemed to work OK, but when I create a second, manually specified IP address (192.168.0.1) for en1, I don't understand how the system decides which port to use when I'm sitting at the server box trying to use the internet.

I know in the advanced popup you can select a priority for ports, but if I'm sending data to the 192.168.0.0 network, and en1 is the second-choice interface after en0, do I need to wait for the process to somehow 'fail' to send on en0 before it will try en1?

I followed the instructions on osxfaq.com, but they weren't explicitly for Server, so I'm wondering if the IPFilter service in MOSXS changes the ipfw/nat landscape somehow?

Ideas?

Thanks,
Fraser</STRONG>

If I understand the question correctly, the answer is that the underlying BSD Unix layer will establish a table of IP routes to known networks, and your packets will be routed accordingly.

For example, in the setup you've described, the routing table would have an entry for the 192.168.0.0 network, an entry for the DHCP network, and an additional default entry. If your packets don't have an address in you "local" 192.168.0.0 range they will be sent to the default entry, which would be your DHCP network attached to your "other" interface. If you open up a terminal window and type "netstat -rn" you can see the route entries for yourself. For more information you could try "man netstat" and "man route".

Cheers,

-Nathan