chmac

#!/bin/bash
#
#	20081116	Brandon Pierce <brandon@ihashacks.com>
#
#	Increments to the next valid MAC address for an interface,
#	looping through all possible MAC addresses.
#
#	History:
#
#	-20081116 - Initial release
#	-20081123 - 

IF=eth1
DEFMAC="00:15:00:1d:ca:ca"

usage()
{
   	echo "Usage: `basename $0` [-i <interface>] [-m <mac address>] [-v verbose]"
	echo -e "\t\t [-d default]"
	exit 1
}

if [ ${#@} -eq 0 ]; then
	usage
fi

default()
{
	echo "Setting mac address for $IF to default of $DEFMAC"
	sudo /sbin/ifconfig $IF hw ether $DEFMAC
	exit 0
}

manual()
{
	echo "Manually setting mac address for $IF to $MAC"
	sudo /sbin/ifconfig $IF hw ether $MAC
	exit 0
}

random()
{
	echo "Random feature not yet implemented"
	exit 1
}

setintf()
{
	echo "Setting interface to $IF"
	#IF="$OPTARG"
}

while getopts im:hvdr o
do case "$o" in
	i) IF="$OPTARG" && setintf;;
	m) MAC="$OPTARG" && manual;;
	h) usage;;
	v) set -x;;
	d) default;;
	r) random;;
esac
done

#
# Use all but the last subscript of our current MAC to define our prefix
# Set the last subscript to be our current MAC suffix
#
MACPFX=`/sbin/ifconfig $IF | grep HWaddr | awk ' { print $5 } ' | cut -c 1-14`
MACSFX=`/sbin/ifconfig $IF | grep HWaddr | awk ' { print $5 } ' | \
		awk -F: ' { print $6 } '`
		
#
# Convert our current MAC suffix to base 10 for incrementing
#
DECSFX=`printf "%d\n" 0x$MACSFX`

#
# Increment the decimal value by 1 unless the total will exced 0xff,
# otherwise it will reset to 1
#
if [ $(($DECSFX+1)) -lt "256" ]; then
		DECSFX=$(($DECSFX+1));
else
		DECSFX=1;
fi

#
# Convert our new suffix to base 16
#
NEWSFX=`printf "%02X\n" $DECSFX`

#
# Concatenate variables and update the interface
#
NEWMAC=`echo $MACPFX:$NEWSFX`
echo "Setting mac address for $IF to $NEWMAC"
sudo /sbin/ifconfig $IF hw ether $NEWMAC