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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, Host, Switch
from mininet.log import info, warn
from mininet.moduledeps import pathCheck
from mininet.util import quietRun
import re
from tempfile import NamedTemporaryFile
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 ):
"Check dependencies and warn about firewalling"
pathCheck( 'brctl', moduleName='bridge-utils' )
# Disable Linux bridge firewalling so that traffic can flow!
for table in 'arp', 'ip', 'ip6':
cmd = 'sysctl net.bridge.bridge-nf-call-%stables' % table
out = quietRun( cmd ).strip()
if out.endswith( '1' ):
warn( 'Warning: Linux bridge may not work with', out, '\n' )
class NAT( Node ):
"NAT: Provides connectivity to external network"
def __init__( self, name, subnet='10.0/8',
localIntf=None, flush=False, **params):
"""Start NAT/forwarding between Mininet and external network
subnet: Mininet subnet (default 10.0/8)
flush: flush iptables before installing NAT rules"""
super( NAT, self ).__init__( name, **params )
self.subnet = subnet
self.localIntf = localIntf
self.flush = flush
self.forwardState = self.cmd( 'sysctl -n net.ipv4.ip_forward' ).strip()
def config( self, **params ):
"""Configure the NAT and iptables"""
super( NAT, self).config( **params )
if not self.localIntf:
self.localIntf = self.defaultIntf()
if self.flush:
self.cmd( 'sysctl net.ipv4.ip_forward=0' )
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' )
# Install NAT rules
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',
'-o', self.localIntf, '-d', self.subnet,'-j ACCEPT' )
self.cmd( 'iptables -t nat -A POSTROUTING',
'-s', self.subnet, "'!'", '-d', 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 terminate( self ):
"Stop NAT/forwarding between Mininet and external network"
# Remote NAT rules
self.cmd( 'iptables -D FORWARD',
'-i', self.localIntf, '-d', self.subnet, '-j DROP' )
self.cmd( 'iptables -D FORWARD',
'-i', self.localIntf, '-s', self.subnet, '-j ACCEPT' )
self.cmd( 'iptables -D FORWARD',
'-o', self.localIntf, '-d', self.subnet,'-j ACCEPT' )
self.cmd( 'iptables -t nat -D POSTROUTING',
'-s', self.subnet, '\'!\'', '-d', self.subnet,
'-j MASQUERADE' )
# Put the forwarding state back to what it was
self.cmd( 'sysctl net.ipv4.ip_forward=%s' % self.forwardState )
super( NAT, self ).terminate()
class Server( Host ):
"Run sshd in a net/mnt/pid/uts namespace, with private /etc/hosts"
ns = [ 'net', 'mnt', 'pid', 'uts' ]
overlayDirs = [ '/etc', '/var/run', '/var/log' ]
privateDirs = [ '/var/run/sshd', ]
def __init__( self, *args, **kwargs ):
"""Add overlay dirs and private dirs, and change permissions
ssh: run sshd? (True)"""
kwargs.setdefault( 'inNamespace', True )
kwargs.setdefault( 'ns', self.ns )
kwargs.setdefault( 'privateDirs', self.privateDirs )
kwargs.setdefault( 'overlayDirs', self.overlayDirs )
kwargs.setdefault( 'ssh', True )
super( Server, self ).__init__( *args, **kwargs )
# Change permissions, mainly for ssh
for pdir in self.privateDirs:
self.cmd( 'chown root:root', pdir )
self.cmd( 'chmod 755', pdir )
@staticmethod
def updateHostsFiles( servers, tmpdirs=[ '/tmp', '/var/tmp' ] ):
"""Update local hosts files on a list of servers
servers: list of servers
tmpdir: tmp dir shared between mn and servers"""
# For large configurations it will be more efficient
# to use a DNS server
hosts = ( '# Mininet hosts file\n'
'127.0.0.1 localhost %s\n' +
''.join( '%s %s\n' % ( t.IP(), t )
for t in servers ) )
for s in servers:
dirs = ( getattr( s, 'overlayDirs', [] ) +
getattr( s, 'privateDirs', [] ) )
if '/etc' in dirs:
tmpdirs = [ d for d in tmpdirs if d not in dirs ]
if tmpdirs:
with NamedTemporaryFile( dir=tmpdirs[ 0 ] ) as tmpfile:
tmpfile.write( hosts % s )
tmpfile.flush()
s.cmd( 'cp', tmpfile.name, '/etc/hosts' )
else:
warn( 'not updating hosts file on %s\n' % s )
def service( self, cmd ):
"""Start or stop a service
usage: service( 'ssh stop' )"""
self.cmd( '/etc/init.d/%s' % cmd )
def motd( self ):
"Return login message as a string"
return 'Welcome to Mininet host %s at %s' % ( self, self.IP() )
def startSSH( self, motdPath='/var/run/motd.dynamic' ):
"Update motd, Clear out utmp/wtmp/btmp, and start sshd"
# Note: /var/run and /var/log must be overlays!
assert ( '/var/run' in ( self.overlayDirs + self.privateDirs ) and
'/var/log' in ( self.overlayDirs + self.privateDirs ) )
self.cmd( "echo '%s' > %s" % ( self.motd(), motdPath ) )
self.cmd( 'truncate -s0 /var/run/utmp /var/log/wtmp* /var/log/btmp*' )
# sshd.pid should really be in /var/run/sshd instead of /var/run
self.cmd( 'rm /var/run/sshd.pid' )
self.cmd( '/etc/init.d/ssh start' )
def config( self, **kwargs ):
"""Configure/start sshd and other stuff
ssh: start sshd? (True )"""
super( Server, self ).config( **kwargs )
self.ssh = kwargs.get( 'ssh' )
if self.ssh:
self.startSSH()
if 'uts' in self.ns:
self.cmd( 'hostname', self )
def terminate( self, *args, **kwargs ):
"Shut down services and terminate server"
if self.ssh:
self.service( 'ssh stop' )
super( Server, self ).terminate( *args, **kwargs )