After upgraded my iPhone 3G to OS 3.0, I am studying the new features bought by Apple. Previously my Nokia N95 8G was very convenience to share the 3G connection with the Macbook Pro. Once you connect the Phone to Macbook, it will recognize the 3G modem immediately, and then you just dial *99# under this modem and you can get the Internet connectivity. However, although iPhone also support the 3G network and I indeed have the 3G data plan, but you can not share it under OS 2.2.1 unless you Jail Break and install the PDANet app.

Now, finally Apple release this feature on OS 3.0! That is amazing because Apple really make it very convenient! You just plug the USB cable from your iPhone and MacBook, then click the ON for this feature. Done! Actually you can use bluetooth to achieve it. But I don't want the battery run out so fast...

The most excited thing for me, is I can use it to share the Internet with my dynamips lab! How to do it? Easy like Apple style. See the picture above? That is a test lab I did to try the feature, it works. If you don’t like to use the wired NIC like me, maybe you can have a try.

  1. 1. Get 3G connection. Connect you iPhone and MacBook with the USB cable. Then share the Internet with your laptop. It will create a new interface on your “Network Preferences”, which is “en2” here. And maybe you have noticed that, the Default gateway is 192.168.20.1 according to the DHCP information.


  1. 2. Run GNS3, add one cloud and one router.
  1. 3. Tap the cloud C0 to the interface connect to iPhone, it is “en2”.


  1. 4. Connect one Ethernet interface from Router 0 to C0. For the physical connect, we have done it.
  2. 5. Now you just need to configure your router and configure the iPhone as the default Internet gateway for your entire virtual network.

interface FastEthernet0/0
ip address dhcp
duplex auto
speed auto

ip route 0.0.0.0 0.0.0.0 192.168.20.1

Router#show ntp associations 

      address         ref clock     st  when  poll reach  delay  offset    disp
*~17.151.16.22     17.72.133.54      2    68   512  377  2273.2  996.13   385.9
  1. * master (synced), # master (unsynced), + selected, - candidate, ~ configured

Still can remember the time using Tap interface to share the wireless connection to the virtual. Need to install the Tap interface, tap the dynamips to the Tap interface, then change the firewall and configure a NAT for the wireless interface, need many steps. I admit that I don’t like to install the virtual Tap NIC.