Решил проблему по этой ссылке http://www.kbrandt.com/2009/01/how-to-setup-up-an-emulated-c...Выдержка
Connect your Host Machine to the Virtual Network:
1. In GNS3 Create a cloud by dragging it from the left.
2. Right click the cloud and chose configure.
3. Click on the NIO TAP tab, type in ‘tap0′ to the field and click ‘Add’ and then ‘Apply’.
4. From your Linux host open up a terminal:
a. Install the utilities that let you create tap interfaces: sudo apt-get install uml-utilities
b. Become Root: sudo su -
c. Load the tun module: modprobe tun
d. Create the tunnel interface: tunctl
c. Give the tap interface an IP that matches your network for lab1’s f0/0, i.e. : ifconfig tap0 192.168.1.100 netmask 255.255.255.0 up
d. If using iptables you may need to add some rules like: iptables -I INPUT 1 -i tap0 -j ACCEPT
5. In GNS3 click the Ethernet icon and select fast ethernet. Then click Lab1 first and the cloud and select the tap0 interface.
6. Verify you can reach the IP of Lab1’s FastEthernet 0/0 ip by pinging it from you Linux Host.