NePA TesT: Community Network Emulator

#!/usr/bin/python

"""

Create a network and start sshd(8) on each host.

While something like rshd(8) would be lighter and faster,

(and perfectly adequate on an in-machine network)

the advantage of running sshd is that scripts can work

unchanged on mininet and hardware.

In addition to providing ssh access to hosts, this example

demonstrates:

- creating a convenience function to construct networks

- connecting the host network to the root namespace

- running server processes (sshd in this case) on hosts

"""

import sys

from mininet.net import Mininet

from mininet.cli import CLI

from mininet.log import lg

from mininet.node import Node

from mininet.topolib import TreeTopo

from mininet.link import Link

def TreeNet( depth=1, fanout=2, **kwargs ):

    "Convenience function for creating tree networks."

    topo = TreeTopo( depth, fanout )

    return Mininet( topo, **kwargs )

def connectToRootNS( network, switch, ip, routes ):

    """Connect hosts to root namespace via switch. Starts network.

      network: Mininet() network object

      switch: switch to connect to root namespace

      ip: IP address for root namespace node

      routes: host networks to route to"""

    # Create a node in root namespace and link to switch 0

    root = Node( 'root', inNamespace=False )

    intf = Link( root, switch ).intf1

    root.setIP( ip, intf=intf )

    # Start network that now includes link to root namespace

    network.start()

    # Add routes from root ns to hosts

    for route in routes:

        root.cmd( 'route add -net ' + route + ' dev ' + str( intf ) )

def sshd( network, cmd='/usr/sbin/sshd', opts='-D',

          ip='10.123.123.1/32', routes=None, switch=None ):

    """Start a network, connect it to root ns, and run sshd on all hosts.

       ip: root-eth0 IP address in root namespace (10.123.123.1/32)

       routes: Mininet host networks to route to (10.0/24)

       switch: Mininet switch to connect to root namespace (s1)"""

    if not switch:

        switch = network[ 's1' ]  # switch to use

    if not routes:

        routes = [ '10.0.0.0/24' ]

    connectToRootNS( network, switch, ip, routes )

    for host in network.hosts:

        host.cmd( cmd + ' ' + opts + '&' )

    print

    print "*** Hosts are running sshd at the following addresses:"

    print

    for host in network.hosts:

        print host.name, host.IP()

    print

    print "*** Type 'exit' or control-D to shut down network"

    CLI( network )

    for host in network.hosts:

        host.cmd( 'kill %' + cmd )

    network.stop()

if __name__ == '__main__':

    lg.setLogLevel( 'info')

    net = TreeNet( depth=1, fanout=4 )

    # get sshd args from the command line or use default args

    # useDNS=no -u0 to avoid reverse DNS lookup timeout

    opts = ' '.join( sys.argv[ 1: ] ) if len( sys.argv ) > 1 else (

        '-D -o UseDNS=no -u0' )

    sshd( net, opts=opts )