Re: Reconfiguring network on the fly

["John O'Hagan" <johnohagan@iprimus.com.au>]

On Sat, 18 Feb 2006 07:20 am, Nigel Ridley wrote:

> To Switch Network Setups On The Fly (on reboot original setup is used):
> With the laptop already running (and configured using static ip) as root:
> # dhcpcd eth0 (this configures the nic to dhcp)
> # dhcpcd -k eth0 (to disconnect)
> # ifdown eth0
> # ifup eth0 (to get the static ip config working again).
>
> Hope this is of some use to others.
> If you know a better way then do share it :-)
>
 
Not better; but different: I wrote a small bash script which does this using 
alternative interfaces files (same as those in /etc/network/interfaces); you 
write one for each different networking situation, and place it in a folder 
called ~/.profiles. I call the script in konsole using sudo (any root shell 
would work I guess), and it asks me to pick which profile to use, then brings 
up the appropriate interface. You can add new profiles as they are needed.

Here it is:

<begin>

#!/bin/bash

ethernet=(`mii-tool | gawk -F: '/link/ {print $1}'`)
wireless=(`iwpriv | gawk '/Available/ {print $1}'`)

profiles=~/.profiles
test=(`mii-tool $ethernet | grep "link ok"`)

echo "Enter a profile from the list below" ; echo

select profile in $( ls $profiles ) ; do

	if [ ! -f $profiles/$profile ] ; then
		echo
		echo Huh? ; echo
	else  echo
		echo $profile chosen ; echo
	
		if  [ "$test" ] ; then
			echo Cable connected, using $ethernet ; echo 
			ifdown $ethernet $wireless
			ifup $ethernet -i $profiles/$profile
			
		elif [ "$wireless" ] ; then 
			echo Bringing up wireless interface $wireless ; echo
			ifdown  $ethernet $wireless
			ifup $wireless -i $profiles/$profile
			
		else echo "No networks available"
			sleep 3
			exit
		fi	
	echo
	echo Done
	sleep 3
	exit	
	fi
done

<end>

If anyone is interested, I've also written a much more elaborate (too long to 
post) script that uses kdialog to present a GUI for managing networking 
profiles like these and also wireless connections and other network stuff, 
which I'd be glad to share.

John