[docman]

Hi Guys,

I'm trying to create a software base station on my G5. I've got a built-in AE card, and my g5 is connected to the net via ethernet. This ethernet connection sits behind a router (NAT box), and that router provides DHCP service to everyone on the lan.

What I would like to do is make "connection sharing" simply bridge the Airport connection to the Ethernet connection -- something that the first AirPort BaseStation could do.

Currrently, the connection sharing works, but it does so by creating another virtual network behind my current NAT network. Computers connecting through the shared connection get an address of 10.0.2.* assigned; nowhere do I see an option for controlling this assignment.

I believe this to be a pretty silly omission. Not everyone needs _another_ NAT+DHCP service; I simply want to let my existing router take care of this stuff. (Plus NAT behind NAT is pretty ugly.) I can't imagine what havoc this might cause on a network that already uses the 10.0.2 class...

Anyone have any ideas? I've looked all around for information on this. I'll file a bug at apple ADC, but just wanted to see if anyone else has noticed this, and (cross fingers) maybe has a solution...?

Cheers...

[barney ntd]

Internet sharing in MacOS X always uses natd. You can't change that. However, you can change the IP addresses used for the airport network as follows:

On your base computer, open System Preferences>Network>Airport>TCP/IP, and switch to Configure: Manually. You can then set the IP address and subnet mask to whatever you want (10.0.n.1 and 255.255.255.0 recommended). All the other computers will configure automatically using DHCP.

I think the chances of Apple implementing a transparent bridge are vanishingly small. Send feedback if you like, but I doubt anything will come of it.

Barney.

[docman]

Originally posted by barney ntd:
Internet sharing in MacOS X always uses natd. You can't change that.

Interesting! I checked it out, and it turns out natd is run with the following options:

Code:
/usr/sbin/natd -alias_address [LOCAL IP] -interface en0 -use_sockets -same_ports -unregistered_only -dynamic -clamp_mss

I believe adding "-proxy_only" should do what I want, but in the absence of an editable natd options list, doing this would be somewhat kludgey (eg redirecting /usr/sbin/natd to some perl/python wrapper..).

I think the chances of Apple implementing a transparent bridge are vanishingly small. Send feedback if you like, but I doubt anything will come of it.

I will be sending feedback, and I disagree that it is unlikely to change. Apple wants OS X to be a first-class network citizen, and it is clear that they've been trying to improve the networking features by bringing traditionally command-line tools (eg, ipfw, connection sharing) into the preferences pane.

There is no technical reason why bridging shouldn't work, it just seems to be the case that apple has hardcoded some default operation. It is silly and makes the whole connection sharing option more confusing for someone who wants that sort of control.

The bright side is that I'm sure I can do what I want by using ipfw and nat on my own (eg in a startup script)...

Cheers...

[barney ntd]

I didn't know about the -proxy_only option. If this is really all that's needed, Apple might well add a checkbox to the pref. panel for it.

My pessimism is based on my attempts to persuade them to add interface specific firewall settings. If you run internet sharing, the built-in firewall is useless because it blocks everything from the client computers as well as from the outside. I've been sending feedback about this since 10.1 (or whenever it was the firewall first appeared) with no luck.

Barney.

[Ov3rdraw]

Found something in a Panther Server review at http://www.afp548.com/Articles/Panther/review.html under DHCP:

A quick look at the man page for bootpd, the daemon that services DHCP requests, will show you a wealth of changes not present in the GUI. For example, you can now set up your server to be a DHCP helper and forward on requests to another DHCP server in another subnet by editing the DHCP configuration in your server's local NetInfo database.

bootpd is also in OS X client but I really have no clue. I just passed it in case it's useful...