We have issued tutorials for connecting Windows or Linux to a physical network using gns3, but apparently, there is a little difference for MacOSX.  I recently received an email from one of our readers, Ivan Pletenev. Ivandescribes how to connect GNS3 to internet through wifi-interface in MacOSX. You will find his writeup below. Thanks Ivan!

First of all, like blindhog.net says, we need to edit our GNS3 .net file. After that we will have something like this:

[localhost:3700]

workingdir = /Users/besch/tmp/gns3

[[3640]]

image = /Users/besch/Documents/Documentations/cisco/c3640-jk9o3s-mz.124-16a.bin

ram = 96

chassis = 3640

[[ROUTER R1]]

model = 3640

console = 2002

cnfg = /Users/besch/tmp/gns3/WLANRouter/R1.cfg

slot0 = NM-1FE-TX

f0/0 = nio_tap:/dev/tap0

[GNS3-DATA]

[[Cloud C0]]

connections = R1:f0/0:nio_tap:/dev/tap0

Now we need a loopback interface (tap0). Download and install tuntaposx program from http://tuntaposx.sourceforge.net/

After installing we can check that we have necessary devices by running ‘ls /dev’ command in the console window. If you have tap0..tap15 and tun0..tun15 in your listing, then everything is ok.

But we still don’t have the created tap interface.  To create tap0 interface all we need is just open our GNS3-project. But it has to be opened with root privileges. Execute this command in the console:

Now we can open our project. Then we need to set up our new tap0 interface:

The last thing – setting up router’s interface in GNS3 and checking connection:

2 . Now let’s try to connect our R1 with internet. I remind you that we have an wireless connection (interface en1, ip 10.189.249.130). All what we need to do is to use NAT:

Lets check do we have IP Forwarding turned on?

If we’ve got 1 – it’s on, if 0 – then we have to turn it on:

The same thing for the firewall:

if we’ve got 0 – we need to turn it on:

Now let’s run natd and add rule for firewall:

The last thing – setting up router’s gateway of last resort in GNS3 and checking connection: