Leopard server 10.5.6 with two nic card and two hostname

Question

Hi,
Here is what I am intending to do but don't know how:
-setup a Mac server that has 2 built-in nic.
-nic1 is setup as a DHCP, has proper hostname, DNS, etc. and connects to internet and is easy when you configure it as a server while is connected.
-But, my other nic2 is not DHCP and is cut off from outside and is intended for internal research, but given a proper IP and hostname.
If I want to install the server, then without internet connection it is hard to complete the setup and If I do then it assigns the hostname pointing to the nic1 (which i don't want)
How should I go about this? I tried both way, but Mac picks the hostname that is associated with nic1 always.
Any help is appreciated!
Thanks

Answer 1

Can you do what you want? Sure. (If I understand what you're up to.) But it gets a little ugly.
It's easier to use a firewall-router-NAT device here.
Dual-NIC configurations and IP are an interesting case.
A firewall-router-NAT configuration and the resulting IP routing works out of the box. It also avoids the case where users and software are active on the firewall (as is the case with a dual-NIC host system acting as a firewall), and where these activities happen to modify the firewall configuration; this whether by accident, by intention, or through an exploit. Firewalls are best kept locked down.
If you want to learn IP routing and preferred paths and other network-level considerations, then by all means do continue to work with a dual-NIC host system. (This isn't specific to Mac, either. This is simply how IP and IP routing works. There's no concept of automatically returning the packets of a connection out the same controller that the connection arrived on, for instance. And various IP protocols don't use connections.)
As for DNS and particularly with NAT, you'll probably end up with a split configuration. I'd tend to have an external DNS provider translate the public DNS domain and the public address, and have the NAT box (with port forwarding) map that to the appropriate private IP address. Within the private address space, a private DNS domain (a subdomain of a public registered domain, or a separate registered domain) uses the local (private) DNS server to resolve its queries, and that DNS server forwards queries for which it is not authoritative to the organization's public DNS server.
Do use node.foo.example.com and node.example.com (where you own example.com) or use node.example.com and node.example.net (where you hold both domains), with the former being external and the latter being the internal address space. Having the same name resolve to two different IP addresses gets weird, as (for instance) a laptop moving between domains (particularly in the co-presence of that abomination known as NAT) may not end up routing its IP traffic where you expect. Having the convention of a specific internal subdomain or a specific internal domain also makes the "inside versus outside" distinction very clear, too. It's possible to use a completely private domain internally, but (given ICANN is opening up TLDs, and in the absence of an ICANN-reserved internal-only domain) I don't recommend that.
If you want to continue with the original course of action, this IP routing and split DNS is a common question. Dig around in the forums, and dig around specifically for discussions of IP default routing, for split-brain or split-horizon or split-zone DNS, consider acquiring Cricket Liu's DNS book (which is what we all usually go read when we hit a DNS weirdness), and for tools such as the CutEdge Systems DNS Enabler tool.