This script takes a list of space separated `desiredInterfaceName=HWaddr`, and renames them if necessary after network has been setup. Useful in OpenWRT 18+ and other embedded distros where udev is not available for remapping. Uses `ifconfig`, `awk`, `cut`. and `grep`.

nicrename.sh

#!/bin/sh /etc/rc.common
# OpenWRT udev-less physical interface renamer
#
# Place in /etc/init.d/ with +x
# /etc/init.d/<scriptname> enable
# /etc/init.d/<scriptname> enabled && echo on

# start after networking and logging
START=13

bindings="if1=MAC1 if2=MAC2 if3=MAC3"

start() {
	# Generate IFACE MAC list
	MACS=$(ifconfig -a | awk '/^eth/ {printf $1" "$5"\\n"}')
	for i in $bindings; do
		NEWNAME=$(echo $i | cut -d'=' -f 1)
		MAC=$(echo $i | cut -d'=' -f 2)
		OLDNAME=$(echo -e $MACS | grep $MAC | cut -d' ' -f 1)
		if [ "$OLDNAME" -a "$NEWNAME" != "$OLDNAME" ]; then
			ip link set ${OLDNAME} down
			ip link set ${OLDNAME} name ${NEWNAME}
			ip link set ${NEWNAME} up
		fi
	done

	# Rename the remaining ethN starting from 0
	N=0
	MACS=$(ifconfig -a | awk '/^eth/ {printf $1"="$5" "}')
	for i in $MACS; do
		OLDNAME=$(echo $i | cut -d'=' -f 1)
		MAC=$(echo $i | cut -d'=' -f 2)
		NEWNAME=eth$N
		N=$((N+1))
		if [ "$OLDNAME" -a "$NEWNAME" != "$OLDNAME" ]; then
			ip link set ${OLDNAME} down
			ip link set ${OLDNAME} name ${NEWNAME}
			ip link set ${NEWNAME} up
		fi
	done
}