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optimization:using_extra_ports_as_a_network_switch

Using extra ports as a network switch

Overview

I ran into this problem with hardware from Soekris, a nice little device designed for network equipment. It comes with 4 NIC's and a PCI slot which you can plug a wireless card into. It is pretty low on memory, and the processor is slower than most smart phones, but it makes a nice IPFire machine.

It is those 4 NIC's that bothered me. I never use them. Sometimes, I set up Red/Green/Blue and put Blue on a WAP, but rarely do I need Red/Green/Blue/Orange. So, I wanted to see if I could use the extra ports as a switch, similar to some low end consumer products.

Reading some documents, specifically one from Soekris and a wiki article by Arne here at IPFire, I came upon a good, tested solution. With this, you can use as many NIC's as you have.

How To

First, determine which ports you will use for your required setup. In most cases, you will want Red/Green/Blue, with Blue being set up on a wireless card. Do the normal install, using only the minimum you need.

After you are done with the setup, ssh into the firewall and see what devices are being used, and which ones are available. One way to find all NIC's in a system is: cat /proc/net/dev In my case it showed (I've cut off part of the output because it had tons of columns):

 Inter-| Receive       
 face |  bytes      packets 
 red0:   14654744   19270
 tun0:   22539     261 
 green0: 2132884   12490 
 lo:     2632      30 
 eth2:       0       0 
 eth3:       0       0 

As you can see, IPFire has set the first two NIC's to red0 and green0, then put the other two NIC's as the standard eth2 & eth3. These are the NIC's we will use to set up our bridge.

Create the file /etc/init.d/bridge with the following contents:

#!/bin/sh
########################################################################
# Begin $rc_base/init.d/bridge
#
# Description : Skript to use more than one NIC's as green net
#
# Authors     : Arne Fitzenreiter - arne_f@ipfire.org
#
# Version     : 01.00
#
# Notes       : http://wiki.ipfire.org/en/configuration/network/bridge-green-blue
#               Modified Rod Rodolico, 20151105
#
# Script is changed from Arne's original to use all ports listed herein as
# extra green ports.
#
########################################################################
 
. /etc/sysconfig/rc
. ${rc_functions}
 
case "${1}" in
	start)
		boot_mesg "Create bridge for green net..."
		# down green0
		ip link set green0 down
		# rename green0 to eth1
                ip link set green0 name eth1
		# create new bridge green0
		brctl addbr green0
		# wait 2 seconds because udev try to rename the nics
		# if the real green nic was added to fast...
		sleep 2
		# Add real green nic and the unused ones
		brctl addif green0 eth1
                # add all the unused nics here
                brctl addif green0 eth2
                brctl addif green0 eth3
		# Bring nic's up
		ip link set eth1 up
		ip link set eth2 up
		ip link set eth3 up
		;;
 
	stop)
		boot_mesg "Remove bridge for green net......"
		# Bring nic's down
		ip link set eth1 down
		ip link set eth2 down
		ip link set eth3 down
		# Bring bridge down
		ip link set green0 down
		# Delete Bridge
		brctl delbr green0
		# rename eth1 to green0
		ip link set eth1 name green0
		;;
	*)
		echo "Usage: ${0} {start|stop}"
		exit 1
		;;
esac
 
# End $rc_base/init.d/bridge 

Now, you should set permissions on the script, then create links from the appropriate run levels

chmod 754 /etc/init.d/bridge
ln -s /etc/init.d/bridge /etc/rc.d/rc3.d/S19bridge
ln -s /etc/init.d/bridge /etc/rc.d/rc0.d/K82bridge
ln -s /etc/init.d/bridge /etc/rc.d/rc6.d/K82bridge

Sources

optimization/using_extra_ports_as_a_network_switch.txt · Last modified: 2018/09/18 21:03 by Jon