[mattyb]

I've looked at a few forum threads, Google searches and I'm obviously missing something basic to get this working.

Modem (ADSL) - ethernet - iMac - Airport (Internet Sharing on) - MacBook

I'm not sure that I've got the correct settings to exploit the Internet sharing. Sorry if this sounds confused.

The iMac has Airport settings of :

IP : 12.23.45.56 - this is not the actual IP
Subnet Mask : 255.255.0.0 - this is the actual mask
No router setting
Self-Assigned IP
Network Name : MacBeauty
Airport is ON
For the Airport, there are no DNS settings

The MacBook has Airport settings of :
IP : 12.23.45.57
Subnet Mask : 255.255.0.0 - this is the actual mask
Router : 12.23.45.56 - the address on the iMac
DNS settings are the same as for the Ethernet connection of the iMac - taken these away and same prob.
No proxy settings for the Airport - should this have the iMac's Airport IP address?

Would appreciate some help, even a slap around the head if it gets my 'new' MacBook to share internet with the iMac.

[seanc]

Are you actually using 192.168.x.x, 172.16.x.x or 10.x.x.x (could possibly be 172.x.x.x I've forgotten) addresses?

You shouldn't need a proxy.
With your current setup:
In a web browser, go to 208.69.34.230
If it takes you to Google, we know it's a DNS issue.

Make the DNS settings on the Airport share on the iMac point to the ethernet IP address.

[mattyb]

Not using any private addresses.

No luck with Google IP address.

Tried iMac Airport DNS server = iMac Ethernet IP address

No luck.

Changed the IPv4 config on the MacBook to 'Using DHCP', still no luck, can't even ping from terminal.

In Finder, I can see the MacBeauty but cannot connect - I also have File sharing setup.

Going to update to 10.5.6 and try again.

EDIT : SOLVED - firewall on the iMac had 'Allow only essential services', I changed it to Allow all incoming connections and it worked.
Now I presume that I'm less secure on that thar intarweb.

Not sure that I like leaving this as it is.