Scripts to support IPv6 networking in Debian pre-boot (initramfs) environment

debian-initramfs-ipv6-hook-script

#!/bin/sh
##########################################################################################
# Script to be placed in /etc/initramfs-tools/hooks/ipv6
#
# These initramfs IPv6 scripts were originally made by zajdee, and were modified by Someguy123
# at Privex Inc. ( https://www.privex.io ) to fix some issues and add debug logging.
#
# It can be found online here: https://gist.github.com/Someguy123/8092bdc9834aa210fb4bd1523e9a1c38
#
# (Original Gist this was based off of (broken script!): https://gist.github.com/zajdee/65aad61f35d3a63c56c7d1cc76c22e14)
#
# Usage:
#   Place this and the other script in their respective locations specified at the top, 
#   make them executable with 'chmod +x /etc/initramfs-tools/{hooks,scripts/init-premount}/ipv6', then
#   edit GRUB_CMDLINE_LINUX in /etc/default/grub to add your static IPv6 details.
#
#   Syntax: ipv6=addr=<address>/<netmask>,gw=<gateway>,iface=<interface>,forwarding=<0/1>,accept_ra=<0/1/2>
#   May optionally add 'll=fe80::1234' to configure a manual link local address
#
#   Example: GRUB_CMDLINE_LINUX="ipv6=addr=2a07:e00::333/64,gw=fe80::1,iface=ens18,forwarding=0,accept_ra=0"
#
#   After installing the scripts and adjusting your kernel cmdline, run:
#   
#     sudo update-initramfs -u; sudo upgrade-grub;
#
##########################################################################################

PREREQ=""

prereqs()
{
    echo "$PREREQ"
}

case $1 in
prereqs)
    prereqs
    exit 0
    ;;
esac

if [ ! -f /bin/ip ] && [ ! -f /usr/sbin/ip ] && [ ! -f /sbin/ip ]; then
    exit 0
fi

. /usr/share/initramfs-tools/hook-functions

# If you're on Debian, it should be in /bin/ip
# For Ubuntu, this should be in /usr/sbin/ip
# If this fails to detect where 'ip' is, run "which ip" or "whereis ip" to check the correct path of the 'ip' tool

if [ -f /usr/sbin/ip ]; then
  copy_exec /usr/sbin/ip
elif [ -f /bin/ip ]; then
  copy_exec /bin/ip
elif [ -f /sbin/ip ]; then
  copy_exec /sbin/ip
else
  echo "WARNING: could not find 'ip' in /bin, /sbin, nor /usr/sbin"
  exit 0
fi

debian-initramfs-ipv6-premount-script

#!/bin/sh
##########################################################################################
# Script to be placed in /etc/initramfs-tools/scripts/init-premount/ipv6
#
# These initramfs IPv6 scripts were originally made by zajdee, and were modified by Someguy123
# at Privex Inc. ( https://www.privex.io ) to fix some issues and add debug logging.
#
# It can be found online here: https://gist.github.com/Someguy123/8092bdc9834aa210fb4bd1523e9a1c38
#
# (Original Gist this was based off of (broken script!): https://gist.github.com/zajdee/65aad61f35d3a63c56c7d1cc76c22e14)
#
# Usage:
#   Place this and the other script in their respective locations specified at the top, 
#   make them executable with 'chmod +x /etc/initramfs-tools/{hooks,scripts/init-premount}/ipv6', then
#   edit GRUB_CMDLINE_LINUX in /etc/default/grub to add your static IPv6 details.
#
#   Syntax: ipv6=addr=<address>/<netmask>,gw=<gateway>,iface=<interface>,forwarding=<0/1>,accept_ra=<0/1/2>
#   May optionally add 'll=fe80::1234' to configure a manual link local address
#
#   Example: GRUB_CMDLINE_LINUX="ipv6=addr=2a07:e00::333/64,gw=fe80::1,iface=ens18,forwarding=0,accept_ra=0"
#
#   After installing the scripts and adjusting your kernel cmdline, run:
#   
#     sudo update-initramfs -u; sudo upgrade-grub;
#
##########################################################################################

PREREQ=""
prereqs()
{
	echo "$PREREQ"
}

parse_options()
{
        local v6opts
        v6opts="$1"
	echo "v6opts='$v6opts'"

	addr=""
	gw=""
	iface=""
	accept_ra=0
	forwarding=0

        local IFS=","
        for x in $v6opts; do
                case $x in
                addr=*)
                        addr=${x#addr=}
                        ;;
                gw=*)
                        gw=${x#gw=}
                        ;;
                iface=*)
                        iface=${x#iface=}
                        ;;
                accept_ra=*)
                        accept_ra=${x#accept_ra=}
                        ;;
                ll=*)
                        ll=${x#ll=}
                        ;;
                forwarding=*)
                        forwarding=${x#forwarding=}
                        ;;
		esac
        done
	echo -ne "\nV6 Var Dump: \n addr = $addr \n gw = $gw \n iface = $iface \n accept_ra = $accept_ra \n ll = $ll \n forwarding = $forwarding \n"
	if [ ! -d /proc/sys/net/ipv6/conf/${iface} ]; then
	    echo "IPv6: Interface ${iface} not found, sorry."
	    return 0
	fi
	echo -ne "IPv6 address: ${addr}\t"
	echo "IPv6 gateway: ${gw}"
	echo -ne "IPv6 iface: ${iface}\t"
        echo "IPv6 link-local address: ${ll}"
	echo ${accept_ra} > /proc/sys/net/ipv6/conf/${iface}/accept_ra
	echo ${forwarding} > /proc/sys/net/ipv6/conf/${iface}/forwarding
	if [ "x${ll}" != "" ]; then
	    /bin/ip -6 address flush dev ${iface}
	    /bin/ip -6 address add ${ll} scope link dev ${iface}
	fi
	/bin/ip link set ${iface} up
	/bin/ip -6 address add ${addr} dev ${iface}
	if [ "x${gw}" != "" ]; then
	    /bin/ip -6 route del default
	    /bin/ip -6 route add default via ${gw} dev ${iface}
	fi
#	/bin/ip -6 addr show dev ${iface}
        return 0
}

case $1 in
# get pre-requisites
prereqs)
	prereqs
	exit 0
	;;
esac

for x in $(cat /proc/cmdline); do
	case ${x} in
	ipv6=*)
		opt="${x#ipv6=}"
		modprobe ipv6
		# syntax: ipv6=addr=<address>/<netmask>,gw=<gateway>,iface=<interface>,forwarding=<0/1>,accept_ra=<0/1/2>
		# colons are not used as delimiters due to them being in use in ipv6 addrs
		parse_options ${opt}
		;;
	esac
done

This didn't work for me on debian 12 (ip binary not found on boot despite no errors from the hook script), but I had success with the scripts from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627164