# network-functions-ipv6

#

# Taken from: network-functions-ipv6

# (P) & (C) 1997-2005 by Peter Bieringer <pb@bieringer.de>

#

#  You will find more information on the initscripts-ipv6 homepage at

#   http://www.deepspace6.net/projects/initscripts-ipv6.html

#

# Version: 2006-08-03

#

#

# Source network-functions due to need of set_link_up()

. ./network-functions

##### Test for IPv6 capabilities

# $1: (optional) testflag: currently supported: "testonly" (do not load a module)

# return code: 0=ok 2=IPv6 test fails

ipv6_test() {

    local fn="ipv6_test"

    local testflag=$1

    if ! [ -f /proc/net/if_inet6 ]; then

        if [ "$testflag" = "testonly" ]; then

            return 2

        else

            modprobe ipv6

            if ! [ -f /proc/net/if_inet6 ]; then

                return 2

            fi

        fi

    fi

    if ! [ -d /proc/sys/net/ipv6/conf/ ]; then

        return 2

    fi

    return 0

}

##### Static IPv6 route configuration

# Set static IPv6 route

#  $1: <IPv6 network> : to route

#  $2: <IPv6 gateway> : over which $1 should be routed (if "::", gw will be skipped)

#  $3: [<Interface>] : (optional)

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem adding route

ipv6_add_route() {

    local fn="ipv6_add_route"

    local networkipv6=$1

    local gatewayipv6=$2

    local device=$3        # maybe empty

    if [ -z "$networkipv6" ]; then

        net_log $"Missing parameter 'IPv6-network' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$gatewayipv6" ]; then

        net_log $"Missing parameter 'IPv6-gateway' (arg 2)" err $fn

        return 1

    fi

    ipv6_test || return 2

    ipv6_test_ipv6_addr_valid $networkipv6 || return 2

    ipv6_test_ipv6_addr_valid $gatewayipv6 || return 2

    if [ -z "$device" ]; then

        local returntxt="$(/sbin/ip -6 route add $networkipv6 via $gatewayipv6 metric 1 2>&1)"

    else

        if [ "$gatewayipv6" = "::" ]; then

            local returntxt="$(/sbin/ip -6 route add $networkipv6 dev $device metric 1 2>&1)"

        else

            local returntxt="$(/sbin/ip -6 route add $networkipv6 via $gatewayipv6 dev $device metric 1 2>&1)"

        fi

    fi

    if [ -n "$returntxt" ]; then

        if echo $returntxt | LC_ALL=C grep -q "File exists"; then

            # Netlink: "File exists"

            true

        elif echo $returntxt | LC_ALL=C grep -q "No route to host"; then

            # Netlink: "No route to host"

            net_log $"'No route to host' adding route '$networkipv6' via gateway '$gatewayipv6' through device '$device'" err $fn

            return 3

        else

            net_log $"Unknown error" err $fn

            return 3

        fi

    fi

    return 0

}

##### automatic tunneling configuration

## Configure automatic tunneling up

# return code: 0=ok 2=IPv6 test fails 3=major problem

ipv6_enable_autotunnel() {

    local fn="ipv6_enable_autotunnel"

    ipv6_test || return 2

    # enable IPv6-over-IPv4 tunnels

    if ipv6_test_device_status sit0; then

        true

    else

        # bring up basic tunnel device

        set_link_up sit0

            if ! ipv6_test_device_status sit0; then

                net_log $"Tunnel device 'sit0' enabling didn't work" err $fn

                return 3

            fi

        # Set sysctls proper (regardless "default")

        /sbin/sysctl -e -w net.ipv6.conf.sit0.forwarding=1 >/dev/null 2>&1

        /sbin/sysctl -e -w net.ipv6.conf.sit0.accept_ra=0 >/dev/null 2>&1

        /sbin/sysctl -e -w net.ipv6.conf.sit0.accept_redirects=0 >/dev/null 2>&1

    fi

    return 0

}

##### Interface configuration

## Add an IPv6 address for given interface

#  $1: <Interface>

#  $2: <IPv6 address[/prefix]>

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_add_addr_on_device() {

    local fn="ipv6_add_addr_on_device"

    local device=$1

    local address=$2

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$address" ]; then

        net_log $"Missing parameter 'IPv6-address' (arg 2)" err $fn

        return 1

    fi

    ipv6_test || return 2

    ipv6_test_ipv6_addr_valid $address || return 1

    ipv6_test_device_status $device

    local result=$?

    if [ "$result" = "0" ]; then

        true

    elif [ "$result" != "11" ]; then

        net_log $"Device '$device' doesn't exist" err $fn

        return 3

    else

        set_link_up $device

            if ! ipv6_test_device_status $device; then

                net_log $"Device '$device' enabling didn't work" err $fn

                return 3

            fi

    fi

    # Extract address parts

    local prefixlength_implicit="$(echo $address | awk -F/ '{ print $2 }')"

    local address_implicit="${address%%/*}"

    # Check prefix length and using '64' as default

    if [ -z "$prefixlength_implicit" ]; then

        local prefixlength_implicit="64"

        local address="$address_implicit/$prefixlength_implicit"

    fi

    /sbin/ip -6 addr replace $address dev $device

    local result=$?

    if [ $result -eq 2 ]; then

        return 0

    elif [ $result -ne 0 ]; then

        net_log $"Cannot add IPv6 address '$address' on dev '$device'" err $fn

        return 3

    fi

    return 0

}

## Remove all IPv6 routes and addresses on given interface (cleanup to prevent kernel crashes)

#  $1: <Interface>

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_cleanup_device() {

    local fn="ipv6_cleanup_device"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

    # Remove all IPv6 routes through this device (but not "lo")

    if [ "$device" != "lo" ]; then

        /sbin/ip -6 route flush dev $device scope global >/dev/null 2>&1

        /sbin/ip -6 route flush dev $device scope site     >/dev/null 2>&1

    fi

    # Remove all IPv6 addresses on this interface

    /sbin/ip -6 addr flush dev $device scope global >/dev/null 2>&1

    /sbin/ip -6 addr flush dev $device scope site     >/dev/null 2>&1

    return 0

}

## Remove all IPv6 6to4 related routes and addresses on given interface

#  $1: <Interface>

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_cleanup_6to4_device() {

    local fn="ipv6_cleanup_6to4_device"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

    # Cleanup 6to4 addresses on this device

    /sbin/ip -6 addr show dev $device scope global permanent | awk '/\<inet6\>/ && $2 ~ /^2002:/ { print $2 }' | while read addr; do

        /sbin/ip -6 addr del ${addr} dev ${device}

    done

    # Get all IPv6 routes through given interface related to 6to4 and remove them

    /sbin/ip -6 route show dev $device | LC_ALL=C grep "^2002:" | while read ipv6net dummy; do

        /sbin/ip -6 route del $ipv6net dev $device

    done

    return 0

}

##### Some address test functions

## Test a given IPv6 address for validity

#  $1: <IPv6 address>

# return code: 0=ok 1=not valid

ipv6_test_ipv6_addr_valid() {

    ipcalc -cs6 $1

}

## Test a given IPv4 address for validity

#  $1: <IPv4 address>

# return code: 0=ok 1=not valid

ipv6_test_ipv4_addr_valid() {

    ipcalc -cs4 $1

}

## Test a given IPv4 address for not a private but unicast one

#  $1: <IPv4 address>

# return code: 0=ok 1=argument error 10=private or not unicast

ipv6_test_ipv4_addr_global_usable() {

    local fn="ipv6_test_ipv4_addr_global_usable"

    local testipv4addr_globalusable=$1

    if [ -z "$testipv4addr_globalusable" ]; then

        return 1

    fi

    # Test for a globally usable IPv4 address now

        # test 0.0.0.0/8

        /bin/ipcalc --network $testipv4addr_globalusable 255.0.0.0     | LC_ALL=C grep -q "NETWORK=0\.0\.0\.0"         && return 10

        # test 10.0.0.0/8         (RFC 1918 / private)

        /bin/ipcalc --network $testipv4addr_globalusable 255.0.0.0     | LC_ALL=C grep -q "NETWORK=10\.0\.0\.0"        && return 10

        # test 127.0.0.0/8        (loopback)

        /bin/ipcalc --network $testipv4addr_globalusable 255.0.0.0     | LC_ALL=C grep -q "NETWORK=127\.0\.0\.0"     && return 10

        # test 169.254.0.0/16 (APIPA / DHCP link local)

        /bin/ipcalc --network $testipv4addr_globalusable 255.255.0.0 | LC_ALL=C grep -q "NETWORK=169\.254\.0\.0" && return 10

        # test 172.16.0.0/12    (RFC 1918 / private)

        /bin/ipcalc --network $testipv4addr_globalusable 255.240.0.0 | LC_ALL=C grep -q "NETWORK=172\.16\.0\.0"    && return 10

        # test 192.168.0.0/16 (RFC 1918 / private)

        /bin/ipcalc --network $testipv4addr_globalusable 255.255.0.0 | LC_ALL=C grep -q "NETWORK=192\.168\.0\.0" && return 10

        # test 224.0.0.0/3        (multicast and reserved, broadcast)

        /bin/ipcalc --network $testipv4addr_globalusable 224.0.0.0     | LC_ALL=C grep -q "NETWORK=224\.0\.0\.0"     && return 10

    return 0

}

## Test a given device for status

#  $1: <Interface>

# return code: 0=ok 1=argument error 10=not exists 11=down

ipv6_test_device_status() {

    local fn="ipv6_test_device_status"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    # Test if device exists

    if [ ! -d "/sys/class/net/${device}" ]; then

        # not exists

        return 10

    fi

    # Test if device is up

    if /sbin/ip link show dev $device 2>/dev/null | LC_ALL=C grep -q "UP"; then

        # up

        return 0

    else

        # down

        return 11

    fi

}

## Create 6to4 prefix

#  $1: <IPv4 address>

# stdout: <6to4address>

# return code: 0=ok 1=argument error

ipv6_create_6to4_prefix() {

    local fn="ipv6_create_6to4_prefix"

    local ipv4addr=$1

    if [ -z "$ipv4addr" ]; then

        net_log $"Missing parameter 'IPv4 address' (arg 1)" err $fn

    fi

    local major1="${ipv4addr%%.*}"

    local minor1="$(echo $ipv4addr | awk -F. '{ print $2 }')"

    local major2="$(echo $ipv4addr | awk -F. '{ print $3 }')"

    local minor2="$(echo $ipv4addr | awk -F. '{ print $4 }')"

    if [ -z "$major1" -o -z "$minor1" -o -z "$major2" -o -z "$minor2" ]; then

        return 1

    fi

    if [ $major1 -eq 0 ]; then

        local block1="$(printf "%x" $minor1)"

    else

        local block1="$(printf "%x%02x" $major1 $minor1)"

    fi

    if [ $major2 -eq 0 ]; then

        local block2="$(printf "%x" $minor2)"

    else

        local block2="$(printf "%x%02x" $major2 $minor2)"

    fi

    local prefix6to4="2002:$block1:$block2"

    echo "$prefix6to4"

    return 0

}

## Check and create 6to4 tunnel relay address

#  $1: <IPv4 address|IPv6to4 address>

# stdout: <tunnel relay address>

# return code: 0=ok 1=argument error

ipv6_create_6to4_relay_address() {

    local fn="ipv6_create_6to4_relay_address"

    local addr=$1

    if [ -z "$addr" ]; then

        net_log $"Missing parameter 'address' (arg 1)" err $fn

        return 1

    fi

    # Check

    if ipv6_test_ipv4_addr_valid $addr ; then

        # ok, an IPv4 one

        if ipv6_test_ipv4_addr_global_usable $addr; then

            # IPv4 globally usable

            local ipv6to4_relay="::$addr"

        else

            net_log $"Given address '$addr' is not a global IPv4 one (arg 1)" err $fn

            return 1

        fi

    else

        net_log $"Given address '$addr' is not a valid IPv4 one (arg 1)" err $fn

        return 1

    fi

    echo "$ipv6to4_relay"

    return 0

}

##### 6to4 tunneling setup

## Configure 6to4 tunneling up

#  $1: <Interface> : only "tun6to4" is supported

#  $2: <IPv4 address> : global IPv4 address of interface (will be used to generate 6to4 prefix)

#  $3: [<IPv6 suffix>] : for 6to4 prefix (optional, default is "::1")

#  $4: [<MTU>] : MTU of tunnel device (optional, default is automatic)

#  $5: [<IPv4 address>] : local IPv4 address of tunnel interface (required in case of 6to4 behind NAT)

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_add_6to4_tunnel() {

    local fn="ipv6_add_6to4_tunnel"

    local device=$1

    local globalipv4=$2

    local globalipv6to4suffix=$3

    local mtu=$4

    local localipv4=$5

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$globalipv4" ]; then

        net_log $"Missing parameter 'global IPv4 address' (arg 2)" err $fn

        return 1

    fi

    # Check device

    if [ "$device" != "tun6to4" ]; then

        net_log $"Given device '$device' is not supported (arg 1)" err $fn

        return 1

    fi

    # Copy global IPv4 address to local if last one is not given

    if [ -z "$localipv4" ]; then

        localipv4="$globalipv4"

    fi

    ipv6_test || return 2

    # Generate 6to4 address

    local prefix6to4="$(ipv6_create_6to4_prefix $globalipv4)"

    if [ $? -ne 0 -o -z "$prefix6to4" ]; then

        return 3

    fi

    if [ -z "$globalipv6to4suffix" ]; then

        local address6to4="${prefix6to4}::1/16"

    else

        local address6to4="${prefix6to4}::${globalipv6to4suffix}/16"

    fi

        ipv6_add_tunnel_device tun6to4 0.0.0.0 $address6to4 $localipv4

        if [ $? -ne 0 ]; then

            local retval=3

        else

            local retval=0

        fi

        # Add unspecific unreachable route for local 6to4 address space

        /sbin/ip route add unreach ${prefix6to4}::/48

    # Set MTU, if given

    if [ -n "$mtu" ]; then

        ipv6_set_mtu $device $mtu

    fi

    return $retval

}

## Configure all 6to4 tunneling down

#  $1: <Interface> : only "tun6to4" is supported

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_cleanup_6to4_tunnels() {

    local fn="ipv6_cleanup_6to4_tunnels"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    # Check device

    if [ "$device" != "tun6to4" ]; then

        net_log $"Given device '$device' is not supported (arg 1)" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

        ipv6_del_tunnel_device tun6to4

        # Remove all unspecific unreachable routes for local 6to4 address space

        /sbin/ip -6 route | LC_ALL=C grep "^unreachable 2002:.*/48 dev lo" | while read token net rest; do

            /sbin/ip route del unreach $net

        done

    return 0

}

## Configure 6to4 tunneling down

#  $1: <Interface> : only "tun6to4" is supported

#  $2: <IPv4 address> : global address of local interface

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_del_6to4_tunnel() {

    local fn="ipv6_del_6to4_tunnel"

    local device=$1

    local localipv4=$2

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$localipv4" ]; then

        net_log $"Missing parameter 'local IPv4 address' (arg 2)" err $fn

        return 1

    fi

    # Check device

    if [ "$device" != "tun6to4" ]; then

        net_log $"Given device '$device' is not supported (arg 1)" err $fn

        return 1

    fi

    ipv6_test || return 2

        ipv6_del_tunnel_device tun6to4

        local retval=$?

        # Remove unspecific unreachable route for local 6to4 address space

        /sbin/ip route del unreach ${prefix6to4}::/48

    return $retval

}

## Configure a static tunnel device up

#  $1: <Interface>

#  $2: <IPv4 address> : of foreign tunnel

#  $3: [<IPv6 address>] : local one of a P-t-P tunnel (optional)

#  $4: [<IPv4 address>] : local one of tunnel (optional)

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_add_tunnel_device() {

    local fn="ipv6_add_tunnel_device"

    local device=$1

    local addressipv4tunnel=$2

    local addressipv6local=$3

    local addressipv4tunnellocal=$4

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$addressipv4tunnel" ]; then

        net_log $"Missing parameter 'IPv4-tunnel address' (arg 2)" err $fn

        return 1

    fi

    if [ -z "$addressipv4tunnellocal" ]; then

        local addressipv4tunnellocal="any"

    fi

    ipv6_test || return 2

    if ! ipv6_test_device_status $device; then

        local ttldefault="$(/sbin/sysctl -e net.ipv4.ip_default_ttl | awk '{ print $3 }')"

        if [ -z "$ttldefault" ]; then

            local ttldefault=64

        fi

        # Test whether remote IPv4 address was already applied to another tunnel

        if [ "$addressipv4tunnel" != "0.0.0.0" -a "$addressipv4tunnel" != "any" ]; then

            /sbin/ip tunnel show remote $addressipv4tunnel 2>/dev/null | LC_ALL=C grep -w "ipv6/ip" | while IFS=":" read devnew rest; do

                if [ "$devnew" != "$device" ]; then

                    net_log $"Given remote address '$addressipv4tunnel' on tunnel device '$device' is already configured on device '$devnew'" err $fn

                    return 3

                fi

            done

        fi

        /sbin/ip tunnel add $device mode sit ttl $ttldefault remote $addressipv4tunnel local $addressipv4tunnellocal

        if [ $? -ne 0 ]; then

            return 3

        fi

        # Test, whether "ip tunnel show" reports valid content

        if ! /sbin/ip tunnel show $device 2>/dev/null | LC_ALL=C grep -q -w "remote"; then

            net_log $"Tunnel device '$device' creation didn't work" err $fn

            return 3

        fi

        set_link_up $device

        if ! ipv6_test_device_status $device; then

            net_log $"Tunnel device '$device' bringing up didn't work" err $fn

            return 3

        fi

        # Set sysctls proper (regardless "default")

        /sbin/sysctl -e -w net.ipv6.conf.$SYSCTLDEVICE.forwarding=1 >/dev/null 2>&1

        /sbin/sysctl -e -w net.ipv6.conf.$SYSCTLDEVICE.accept_ra=0 >/dev/null 2>&1

        /sbin/sysctl -e -w net.ipv6.conf.$SYSCTLDEVICE.accept_redirects=0 >/dev/null 2>&1

        if [ -n "$addressipv6local" ]; then

            # Setup P-t-P address

            ipv6_add_addr_on_device $device $addressipv6local

            if [ $? -ne 0 ]; then

                return 3

            fi

        fi

    else

        false

    fi

    return 0

}

## Configure a static tunnel device down

#  $1: <Interface>

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_del_tunnel_device() {

    local fn="ipv6_del_tunnel_device"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

    if ipv6_test_device_status $device; then

        ipv6_cleanup_device $device

    else

        if [ "$device" != "sit0" ]; then

            false

        fi

    fi

    if [ "$device" != "sit0" ]; then

        if /sbin/ip tunnel show $device 2>/dev/null | LC_ALL=C grep -q -w "ipv6/ip"; then

            /sbin/ip tunnel del $device

            if ipv6_test_device_status $device; then

                return 3

            fi

        else

            false

        fi

    fi

    return 0

}

## Cleanup all dedicated tunnel devices

ipv6_cleanup_tunnel_devices() {

    local fn="ipv6_cleanup_tunnel_devices"

    ipv6_test testonly || return 2

    # Find still existing tunnel devices and shutdown and delete them

    /sbin/ip tunnel show | awk -F: '/\<ipv6\/ip\>/ { print $1 }' | while read device; do

        ipv6_del_tunnel_device $device

    done

    return 0

}

## Get address of a dedicated tunnel

#  $1: <Interface>

#  $2: local|remote : local or remote address

# stdout: <IPv4 address> if available

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_get_ipv4addr_of_tunnel() {

    local fn="ipv6_get_local_ipv4_of_tunnel"

    local device=$1

    local selection=$2

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$selection" ]; then

        net_log $"Missing parameter 'selection' (arg 2)" err $fn

        return 1

    fi

    if [ "$selection" != "local" -a "$selection" != "remote" ]; then

        net_log $"Unsupported selection '$selection' specified (arg 2)" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

    ipv6_test_device_status $device

    if [ $? != 0 -a $? != 11 ]; then

        # Device doesn't exist

        return 3

    fi

    # Device exists, retrieve address

    if [ "$selection" = "local" ]; then

        local tunnel_local_ipv4addr="$(/sbin/ip tunnel show $device | awk '{ print $6 }')"

    elif [ "$selection" = "remote" ]; then

        local tunnel_local_ipv4addr="$(/sbin/ip tunnel show $device | awk '{ print $4 }')"

    fi

    if [ $? != 0 ]; then

        return 3

    fi

    if [ "$tunnel_local_ipv4addr" = "any" ]; then

        local tunnel_local_ipv4addr="0.0.0.0"

    fi

    echo "$tunnel_local_ipv4addr"

    return 0

}

## Get IPv4 address of a device

#  $1: <Interface>

# stdout: <IPv4 address> if available

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem (more than one IPv4 address applied)

ipv6_get_ipv4addr_of_device() {

    local fn="ipv6_get_ipv4addr_of_device"

    local device=$1

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    ipv6_test_device_status $device

    if [ $? != 0 -a $? != 11 ]; then

        # Device doesn't exist

        return 3

    fi

    # Device exists, retrieve the first address only

    local ipv4addr="$(/sbin/ip -o -4 addr show dev $device | awk '{ print $4 }' | awk -F/ '{ print $1; exit }')"

    if [ $? != 0 ]; then

        return 3

    fi

    if [ "$ipv4addr" = "any" ]; then

        local ipv4addr="0.0.0.0"

    fi

    echo "$ipv4addr"

    return 0

}

## Set IPv6 MTU for a device

#  $1: <Interface>

#  $2: <IPv6 MTU>

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_set_mtu() {

    local fn="ipv6_set_mtu"

    local device=$1

    local ipv6_mtu=$2

    if [ -z "$device" ]; then

        net_log $"Missing parameter 'device' (arg 1)" err $fn

        return 1

    fi

    if [ -z "$ipv6_mtu" ]; then

        net_log $"Missing parameter 'IPv6 MTU' (arg 2)" err $fn

        return 1

    fi

    # Check range

    if [ $ipv6_mtu -lt 1280 -o $ipv6_mtu -gt 65535 ]; then

        net_log $"Given IPv6 MTU '$ipv6_mtu' is out of range" err $fn

        return 1

    fi

    ipv6_test testonly || return 2

    # Set value

    /sbin/ip link set dev $device mtu $ipv6_mtu

    return 0

}

## Set a default route

#  $1: <IPv6 address> : gateway, can also contain scope suffix (device name), cause a warning if not matching with $2 (but will have precedence)

#  $2: <gateway device>: gateway device (optional in case of $1 is a global address or $1 contains scope suffix)

#  $3: <check device>: (optional) device to check scope and gateway device against (setup is skipped, if not matching)

# return code: 0=ok 1=argument error 2=IPv6 test fails 3=major problem

ipv6_set_default_route() {

    local fn="ipv6_set_default_route"

    local address=$1

    local device=$2

    local device_check=$3

    ipv6_test testonly || return 2

    # Map the unspecified address to nothing

    if [ "$address" = "::" ]; then

        local address=""

    fi

    if [ -n "$address" ]; then

        local addressgw=${address%%%*}

        local device_scope=$(echo $address | awk -F% '{ print $2 }')

        if [ -z "$addressgw" ]; then

            net_log $"Given IPv6 default gateway '$address' is not in proper format" err $fn

            return 3

        fi

        # Scope device has precedence

        if [ -n "$device_scope" -a -n "$device" -a "$device_scope" != "$device" ]; then

            net_log $"Given IPv6 default gateway '$address' has scope '$device_scope' defined, given default gateway device '$device' will be not used" info $fn

            local device=""

        fi

        # Link local addresses require a device

        if echo $addressgw | LC_ALL=C grep -qi "^fe80:"; then

            if [ -z "$device_scope" ]; then

                if [ -z "$device" ]; then

                    net_log $"Given IPv6 default gateway '$address' is link-local, but no scope or gateway device is specified" err $fn

                    return 3

                fi

            fi

        fi

        # Check whether the route belongs to the specific given interface

        if [ -n "$device_check" ]; then

            # Check whether scope device matches given check device

            if [ -n "$device_scope" -a "$device_check" != "$device_scope" ]; then

                # scope device != specific given -> skip

                return 0

            elif [ -n "$device" -a "$device_check" != "$device" ]; then

                # gateway device != specific given -> skip

                return 0

            fi

        fi

        # Set device now, if not given

        if [ -z "$device" ]; then

            local device="$device_scope"

        fi

        if [ -z "$device" ]; then