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148 lines (121 loc) · 5.09 KB
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"""
Node Library for Mininet
This contains additional Node types which you may find to be useful.
"""
from mininet.node import Node, Switch
from mininet.log import info, warn
from mininet.moduledeps import pathCheck
import re
class LinuxBridge( Switch ):
"Linux Bridge (with optional spanning tree)"
nextPrio = 100 # next bridge priority for spanning tree
def __init__( self, name, stp=False, prio=None, **kwargs ):
"""stp: use spanning tree protocol? (default False)
prio: optional explicit bridge priority for STP"""
self.stp = stp
if prio:
self.prio = prio
else:
self.prio = LinuxBridge.nextPrio
LinuxBridge.nextPrio += 1
Switch.__init__( self, name, **kwargs )
def connected( self ):
"Are we forwarding yet?"
if self.stp:
return 'forwarding' in self.cmd( 'brctl showstp', self )
else:
return True
def start( self, _controllers ):
"Start Linux bridge"
self.cmd( 'ifconfig', self, 'down' )
self.cmd( 'brctl delbr', self )
self.cmd( 'brctl addbr', self )
if self.stp:
self.cmd( 'brctl setbridgeprio', self.prio )
self.cmd( 'brctl stp', self, 'on' )
for i in self.intfList():
if self.name in i.name:
self.cmd( 'brctl addif', self, i )
self.cmd( 'ifconfig', self, 'up' )
def stop( self, deleteIntfs=True ):
"""Stop Linux bridge
deleteIntfs: delete interfaces? (True)"""
self.cmd( 'ifconfig', self, 'down' )
self.cmd( 'brctl delbr', self )
super( LinuxBridge, self ).stop( deleteIntfs )
def dpctl( self, *args ):
"Run brctl command"
return self.cmd( 'brctl', *args )
@classmethod
def setup( cls ):
"Make sure our class dependencies are available"
pathCheck( 'brctl', moduleName='bridge-utils' )
class NAT( Node ):
"NAT: Provides connectivity to external network"
def __init__( self, name, inetIntf=None, subnet='10.0/8',
localIntf=None, **params):
"""Start NAT/forwarding between Mininet and external network
inetIntf: interface for internet access
subnet: Mininet subnet (default 10.0/8)="""
super( NAT, self ).__init__( name, **params )
self.inetIntf = inetIntf if inetIntf else self.getGatewayIntf()
self.subnet = subnet
self.localIntf = localIntf
def config( self, **params ):
"""Configure the NAT and iptables"""
super( NAT, self).config( **params )
if not self.localIntf:
self.localIntf = self.defaultIntf()
self.cmd( 'sysctl net.ipv4.ip_forward=0' )
# Flush any currently active rules
# TODO: is this safe?
self.cmd( 'iptables -F' )
self.cmd( 'iptables -t nat -F' )
# Create default entries for unmatched traffic
self.cmd( 'iptables -P INPUT ACCEPT' )
self.cmd( 'iptables -P OUTPUT ACCEPT' )
self.cmd( 'iptables -P FORWARD DROP' )
# Configure NAT
self.cmd( 'iptables -I FORWARD',
'-i', self.localIntf, '-d', self.subnet, '-j DROP' )
self.cmd( 'iptables -A FORWARD',
'-i', self.localIntf, '-s', self.subnet, '-j ACCEPT' )
self.cmd( 'iptables -A FORWARD',
'-i', self.inetIntf, '-d', self.subnet, '-j ACCEPT' )
self.cmd( 'iptables -t nat -A POSTROUTING',
'-o', self.inetIntf, '-s', self.subnet, '-j MASQUERADE' )
# Instruct the kernel to perform forwarding
self.cmd( 'sysctl net.ipv4.ip_forward=1' )
# Prevent network-manager from messing with our interface
# by specifying manual configuration in /etc/network/interfaces
intf = self.localIntf
cfile = '/etc/network/interfaces'
line = '\niface %s inet manual\n' % intf
config = open( cfile ).read()
if ( line ) not in config:
info( '*** Adding "' + line.strip() + '" to ' + cfile + '\n' )
with open( cfile, 'a' ) as f:
f.write( line )
# Probably need to restart network-manager to be safe -
# hopefully this won't disconnect you
self.cmd( 'service network-manager restart' )
def getGatewayIntf( self, fallback='eth0' ):
"""Return gateway interface name
fallback: default device to fall back to"""
routes = self.cmd( 'ip route show' )
match = re.search( r'default via \S+ dev (\S+)', routes )
if match:
return match.group( 1 )
else:
warn( 'There is no default route set.',
'Using', fallback, 'as gateway interface...\n' )
return fallback
def terminate( self ):
"""Stop NAT/forwarding between Mininet and external network"""
# Flush any currently active rules
# TODO: is this safe?
self.cmd( 'iptables -F' )
self.cmd( 'iptables -t nat -F' )
# Instruct the kernel to stop forwarding
self.cmd( 'sysctl net.ipv4.ip_forward=0' )
super( NAT, self ).terminate()