I’ve seen the nat.py example that comes with MiniNet. But I was wondering if there was another way to have a MiniNet host communicate with the internet. Since I am running MiniNet inside a VirtualBox VM, I thought I would just connect one of the external interfaces on the VM to the OVS switch running in MiniNet. I also didn’t want to configure static IP address on all the hosts, so I decided to use DHCP. Now MiniNet hosts only support being created with static IP addresses, but there is a shortcut to have them do DHCP. So the basic steps to get MiniNet hosts using DHCP to get an address and connect to the internet are as follows.
- In the VirtualBox settings for your VM, add an additional interface to the VM and set it to NAT.
- Start up your VM. In my case, the new interface that was added was called eth2 in the VM. Don’t do any special configuration in the VM for the interface, just leave it as is.
- Create a simple one host one switch network and attach the VM interface (eth2 in my case) to the switch.
- Start your MiniNet network.
- Open an xterm to your MiniNet host and issue the following. Note, ny host is called ‘h1’.
- ifconfig h1-eth0 inet 0.0.0.0
- dhclient h1-eth0
After that is done, you should be able to communicate with the internet. I tested it by pinging http://www.google.com.
Note that, instead of adding a new interface to your VirtualBox VM as NAT setting, you could have added it as ‘Bridge Adapter’ and then the host would be communicating on your LAN getting an IP address from your LAN’s DHCP server. But in some cases, that is not desired scenerio.
So I made a small MiniNet script, see below, that automates the above steps and you can use as an example on how to add it to your scripts.
#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Controller
from mininet.cli import CLI
from mininet.link import Intf
from mininet.log import setLogLevel, info
def myNetwork():
net = Mininet( topo=None,
build=False)
info( '*** Adding controller\n' )
net.addController(name='c0')
info( '*** Add switches\n')
s1 = net.addSwitch('s1')
Intf( 'eth2', node=s1 )
info( '*** Add hosts\n')
h1 = net.addHost('h1', ip='0.0.0.0')
info( '*** Add links\n')
net.addLink(h1, s1)
info( '*** Starting network\n')
net.start()
h1.cmdPrint('dhclient '+h1.defaultIntf().name)
CLI(net)
net.stop()
if __name__ == '__main__':
setLogLevel( 'info' )
myNetwork()
And then you can see it in action below.
mininet@mininet-vm:~$ sudo ./hostInternet.py
*** Adding controller
*** Add switches
*** Add hosts
*** Add links
*** Starting network
*** Configuring hosts
h1
*** Starting controller
*** Starting 1 switches
s1
*** h1 : ('dhclient h1-eth0',)
*** Starting CLI:
mininet> h1 ping -c 1 www.google.com
PING www.google.com (74.125.226.112) 56(84) bytes of data.
64 bytes from yyz08s13-in-f16.1e100.net (74.125.226.112): icmp_req=1 ttl=55 time=11.6 ms
--- www.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 11.692/11.692/11.692/0.000 ms
Hope you found this useful.
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