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