Thought I would test the airport sharing mechanism of the Snow Leopard mini-server.
On normal Macs, an adhoc wifi hotspot is easily created with just a quick trip to System Preferences. System Preferences->Sharing->Internet Sharing->Share your connection from <Ethernet> to computers using AirPort.
Absent any tricky DNS or firewall settings, it is just that simple. Then everyone in the vicinity with a Touch or a PC can jump onto your connection, subject to any password restrictions you may have set up. Reversing the move is as simple as unchecking the box in sharing preferences.
How hard could this be on the Snow Leopard Server? Does it still work from System Preferences?
It does not work from System Preferences in the server version. Snow Leopard Server only provides a full blown implementation of NAT (Network Address Translation). NAT must be setup from Server Admin app. It is enabled via a "Gateway Setup" wizard interface, which makes configuring NAT and creating a wifi hotspot a simple affair. Server->Settings->Services->Checkmark NAT box and save. This adds NAT to the services list. But it is grayed out, not yet setup or running.
Click the NAT service in the services list, then the "Overview" tab. In the lower right hand corner is a button to launch the "Gateway Setup Assistant". To simplify NAT setup, the wizard interface makes a series of significant configuration decisions for the server. In this instance, the wizard began with a big warning regarding probable DNS problems.
Believe These Warnings!
Believe this warning! Also believe that the firewall will be enabled with some enhanced security settings.
Creating the ad hoc wifi hotspot is only a little more difficult in the server version than in standard Snow Leopard. Reversing the system wide changes the wizard makes can be a bear. In this case, reversing the changes required wiping out and rebuilding DNS zones, a special trip to the services screen to uncheck NAT even after it is disabled in the services list, and a revisit of firewall settings. If running headless, the ip address may be the only way to access Server Admin after enabling NAT.
Updated - no longer nearly so nasty
Not sure if these problems were cleared up in a service release or I did something wrong the first time around, but rolling back the NAT was as simple as disabling the NAT service and the Firewall. Just like it should be.
Service Export
I get a little smarter every time I do this, and now export-import the DNS and Firewall service settings as a plist file when switching back and forth. Server->Export->Service Settings, pick just DNS, save the plist file someplace safe. Then Server->Import->Service Settings and browse to that saved file location to restore. Repeat for the Firewall.
NAT is simple to setup, no longer a bear to reverse.
The warning that is the first step in the NAT wizard, should be heeded and some preparations made if it is going to be rolled back. Snow Leopard Server is not quite as simple to jump in and out of wifi hotspot mode as the desktop version, but not too bad considering the more powerful options.
The mini server can easily be used as a wifi hot spot, if that is the need. It can easily provide DNS services if that is the need. Switching modes, or configuring simultaneous wifi hotspot and DNS server services requires planning and a fair amount of knowledge to get right.
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