#!/bin/sh
#
# network-functions-ipv6
#
# Taken from:
# (P) & (C) 1997-2001 by Peter Bieringer <pb@bieringer.de>
#
# Version: 2001-07-17a
#
# Extended address detection is enabled, if 'ipv6calc' is installed
#  Available here: http://www.bieringer.de/linux/IPv6/tools/index.html#ipv6calc
#





# Return values
#  0 = ok
#  1 = error occurs
#  2 = not enabled, i.e. no IPv6 kernel support or switched off by configuration

##### Test for "ipv6calc" (used for better existing address detection)
EXISTS_ipv6calc=no	
	if which ipv6calc >/dev/null 2>&1; then
		if ipv6calc --if_inet62addr 3ffe04000100f1010000000000000001 40 | grep -q -v '3ffe:400:100:f101::1/64'; then
			false
		elif ipv6calc --addr2if_inet6 3ffe:400:100::1/64 | grep -q -v '3ffe0400010000000000000000000001 00 40'; then
			false
		else
			EXISTS_ipv6calc=yes
		fi
	else
		false
	fi


##### Test for IPv6 capabilites
# $1: (optional) testflag: currently supported: "testonly" (do not load a module)
test_ipv6() {
	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
					echo $"Kernel is not compiled with IPv6 support"
				return 2
			fi
		fi
	fi

	if [ ! -d /proc/sys/net/ipv6/conf/ ]; then
		return 2
	fi


	if ! which ip 2>&1 >/dev/null; then
		echo $"Utility 'ip' (iproute-package) doesn't exist or isn't executable - non-NBMA-styled tunneling setup won't work!"
		return 2													
	fi

	
	return 0
}


##### Get version of this function libary
getversion_ipv6_functions() {
	local version_ipv6_functions="`cat /etc/sysconfig/network-scripts/network-functions-ipv6 | grep "^# Version:" | awk '{ print $3 }' | sed 's/-//g' | sed 's/[A-Za-z]*$//g'`"
	echo $version_ipv6_functions
}

##### Control IPv6 forwarding

# Control IPv6 forwarding
#  $1: control [yes|no|on|off]
#  $2: network device (if not given, global IPv6 forwarding is set) [OBSOLETE]
forwarding_ipv6() {
	local fw_control=$1
	local fw_device=$2		# maybe empty

	if [ -z "$fw_control" ]; then
		echo $"Missing parameter 'forwarding control' (arg 1)"
		return 1
	fi

	if ! [ "$fw_control" = "yes" -o "$fw_control" = "no" -o "$fw_control" = "on" -o "$fw_control" = "off" ]; then
		echo $"Don't understand forwarding control parameter '$fw_control' (arg 1)"
		return 1
	fi
	
	test_ipv6 || return 2   


	if [ "$fw_control" = "yes" -o "$fw_control" = "on" ]; then
		local status=1
	else
		local status=0
	fi

	# Global control? (if no device is given)
	if [ -z "$fw_device" ]; then
			sysctl -w net.ipv6.conf.all.forwarding=$status >/dev/null
	fi
	
	# Per device control (not implemented in kernel)
	if [ ! -z "$fw_device" ]; then
		echo $"IPv6 forwarding per device cannot be controlled via sysctl - use netfilter6 instead!"
	fi
	
}


##### 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)
ifup_ipv6_route() {
	local networkipv6=$1
	local gatewayipv6=$2
	local device=$3		# maybe empty

	if [ -z "$networkipv6" ]; then
		echo $"Missing parameter 'IPv6-network' (arg 1)"
		return 1
	fi

	if [ -z "$gatewayipv6" ]; then
		echo $"Missing parameter 'IPv6-gateway' (arg 2)"
		return 1
	fi

	test_ipv6 || return 2   

	testipv6_valid $networkipv6 || return 2
	testipv6_valid $gatewayipv6 || return 2

	
	if [ -z "$device" ]; then
			local output="`LC_ALL=C route -A inet6 add $networkipv6 gw $gatewayipv6 2>&1`"
	else
		if [ "$gatewayipv6" = "::" ]; then
				local output="`LC_ALL=C route -A inet6 add $networkipv6 dev $device 2>&1`"
		else
				local output="`LC_ALL=C route -A inet6 add $networkipv6 gw $gatewayipv6 dev $device 2>&1`"
		fi
	fi

	if [ $? -ne 0 ]; then
		if echo $output | grep -i -q 'SIOCADDRT: File exists';  then
			true
		else
			echo $output
			return 2
		fi
	fi

	return 0
}

# Delete a 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)
ifdown_ipv6_route() {
	local networkipv6=$1
	local gatewayipv6=$2
	local device=$3		# maybe empty

	if [ -z "$networkipv6" ]; then
		echo $"Missing parameter 'IPv6-network' (arg 1)"
		return 1
	fi

	if [ -z "$gatewayipv6" ]; then
		echo $"Missing parameter 'IPv6-gateway' (arg 2)"
		return 1
	fi

	test_ipv6 || return 2

	# Test, whether given IPv6 address is valid	
	testipv6_valid $networkipv6 || return 2
	testipv6_valid $gatewayipv6 || return 2

	
	if [ -z "$device" ]; then
			local output="`LC_ALL=C route -A inet6 del $networkipv6 gw $gatewayipv6 2>&1`"
	else
		if [ "$gatewayipv6" = "::" ]; then
				local output="`LC_ALL=C route -A inet6 del $networkipv6 dev $device 2>&1`"
		else
				local output="`LC_ALL=C route -A inet6 del $networkipv6 gw $gatewayipv6 dev $device 2>&1`"
		fi
	fi

	if [ $? -ne 0 ]; then
		if echo $output | grep -i -q 'SIOCDELRT: No such process'; then
			true
		else
			echo $output
			return 2
		fi
	fi

	return 0
}

# Delete all static IPv6 routes through a given interface
#  $1: Interface
#  $2: Gateway match (optional)
ifdown_ipv6_route_all() {
	local device=$1
	local gatewaymatch=$2

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	test_ipv6 || return 2   


	# Get all IPv6 routes through given interface and remove them
	LC_ALL=C route -A inet6 -n | grep "$device\W*$" | while read ipv6net nexthop flags metric ref use iface args; do
		if [ "$iface" = "$device" ]; then
			if [ ! -z "$gatewaymatch" ]; then
				# Test if given gateway matches
				if [ "$gatewaymatch" != "$nexthop" ]; then
					continue
				fi
			fi
			# Only non addrconf (automatic installed) routes should be removed
			if echo $flags | grep -v -q "A"; then
					local output="`LC_ALL=C route -A inet6 del $ipv6net gw $nexthop dev $iface 2>&1`"
			fi
		fi
	done

}


##### automatic tunneling configuration

## Configure automatic tunneling up
ifup_ipv6_autotunnel() {
	test_ipv6 || return 2 


	# enable IPv6-over-IPv4 tunnels
	if test_interface_status sit0; then
		true
	else
		# bring up basic tunnel device
			ifconfig sit0 up

			if ! test_interface_status sit0; then
				echo $"Tunnel device 'sit0' enabling didn't work - FATAL ERROR!"
				return 2
			fi

			# Set sysctls proper (regardless "default")
			sysctl -w net.ipv6.conf.sit0.forwarding=1 >/dev/null
			sysctl -w net.ipv6.conf.sit0.accept_ra=0 >/dev/null
			sysctl -w net.ipv6.conf.sit0.accept_redirects=0 >/dev/null
	fi
	
	return 0
}


## Configure automatic tunneling down
ifdown_ipv6_autotunnel() {
	test_ipv6 || return 2


	if test_interface_status sit0; then

		# disable IPv6-over-IPv4 tunnels (if a tunnel is no longer up)
		if LC_ALL=C route -A inet6 -n | grep "sit0\W*$" | awk '{ print $2 }' | grep -v -q "^::$"; then
			# still existing routes, skip shutdown of sit0
			true
		elif LC_ALL=C ip addr show dev sit0 | grep inet6 | awk '{ print $2 }' | grep -v -q '^::'; then
			# still existing IPv6 addresses, skip shutdown of sit0
			true
		else
			# take down basic tunnel device
				sysctl -w net.ipv6.conf.sit0.forwarding=0 >/dev/null
				sysctl -w net.ipv6.conf.sit0.accept_ra=0 >/dev/null
				sysctl -w net.ipv6.conf.sit0.accept_redirects=0 >/dev/null
			
				ifconfig sit0 down

				if test_interface_status sit0; then
					echo $"Tunnel device 'sit0' is still up - FATAL ERROR!"
					return 2
				fi
		fi
	fi

	return 0
}	


##### static NBMA-styled tunnel configuration

## Configure static tunnels up
#  $1: Interface (not needed - dummy)
#  $2: IPv4 address of foreign tunnel
#  $3: IPv6 route through this tunnel
ifup_ipv6_tunnel() {
	local device=$1
	local addressipv4tunnel=$2
	local routeipv6=$3

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$addressipv4tunnel" ]; then
		echo $"Missing parameter 'IPv4-tunnel address' (arg 2)"
		return 1
	fi

	if [ -z "$routeipv6" ]; then
		echo $"Missing parameter 'IPv6-route' (arg 3)"
		return 1
	fi

	test_ipv6 || return 2


	# Test, whether given IPv6 address is valid	
	testipv6_valid $routeipv6 || return 2
	

	# enable general IPv6-over-IPv4 tunneling
	ifup_ipv6_autotunnel
	if [ $? -ne 0 ]; then
		return 2
	fi
	
   		# Set up a tunnel
		ifup_ipv6_route $routeipv6 ::$addressipv4tunnel sit0
		if [ $? -ne 0 ]; then
			return 2
		fi

	return 0
}	


## Configure static tunnels down
#  $1: Interface (not used - dummy)
#  $2: IPv4 address of foreign tunnel
#  $3: IPv6 route through this tunnel
ifdown_ipv6_tunnel() {
	local device=$1
	local addressipv4tunnel=$2
	local routeipv6=$3

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$addressipv4tunnel" ]; then
		echo $"Missing parameter 'IPv4-tunnel address' (arg 2)"
		return 1
	fi

	if [ -z "$routeipv6" ]; then
		echo $"Missing parameter 'IPv6-route' (arg 3)"
		return 1
	fi

	test_ipv6 || return 2



		# Delete a NBMA-styled tunnel
		ifdown_ipv6_route $routeipv6 ::$addressipv4tunnel sit0
		if [ $? -ne 0 ]; then
			return 2
		fi

	# disable IPv6-over-IPv4 tunneling (if this was the last tunnel)
	ifdown_ipv6_autotunnel

}	


## Remove all IPv6 tunnels for a given tunnel endpoint
#  $1: Interface (not used - dummy)
#  $2: IPv4-tunnel address 
ifdown_ipv6_tunnel_all() {
	local idtuall_device=$1
	local idtuall_tunnel=$2

	if [ -z "$idtuall_device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$idtuall_tunnel" ]; then
		echo $"Missing parameter 'IPv4-tunnel address' (arg 2)"
		return 1
	fi

	test_ipv6 || return 2


	# Get all IPv6 routes through given interface and remove them
	LC_ALL=C route -A inet6 -n | grep "::$idtuall_tunnel" | while read ipv6net nexthop flags metric ref use iface args; do
		if [ "::$idtuall_tunnel" = "$nexthop" ]; then
			if echo $flags | grep -v -q "A"; then
				# Only non addrconf (automatic installed) routes should be removed
				ifdown_ipv6_tunnel $idtuall_device $idtuall_tunnel $ipv6net
			fi
		fi
	done

	# disable IPv6-over-IPv4 tunneling (if this was the last tunnel)
	ifdown_ipv6_autotunnel
	return 0
}


##### Test, whether an IPv6 address exists on an interface
# $1: Device for testing
# $2: Address to test (without prefix)
# $3: Prefix of address $1
# return values: 1:problem, 10:not exists, 11:exits
test_ipv6_address_exists() {
	local testdevice=$1
	local testaddr=$2
	local testprefix=$3

	if [ -z "$testaddr" ]; then
		echo $"Missing parameter 'IPv6AddrToTest' (arg 1)"
		return 1
	fi


	if [ "$EXISTS_ipv6calc" = "yes" ]; then
		# Using ipv6calc and compare against /proc/net/if_inet6

		local convertresult="`ipv6calc --addr2if_inet6 $testaddr/$testprefix`"
		# Split in address, scope and prefix length
		local test_addr="`echo $convertresult | awk '{ print $1 }'`"
		local test_scope="`echo $convertresult | awk '{ print $2 }'`"
		local test_prefixlength="`echo $convertresult | awk '{ print $3 }'`"

		if [ -z "$test_prefixlength" ]; then
			local testresult="`grep "$test_addr .. .. $test_scope .." /proc/net/if_inet6 | grep $testdevice$`"
		else
			local testresult="`grep "$test_addr .. $test_prefixlength $test_scope .." /proc/net/if_inet6 | grep $testdevice$`"
		fi
		if [ ! -z "$testresult" ]; then
			return 11
		else
			return 10
		fi
	else
		# low budget version, only works if given address is in equal form like "ip" displays
		local testresult="`LC_ALL=C ip addr show dev $testdevice | grep inet6 | awk '{ print $2 }' | grep -i "^$testaddr/$testprefix$"`"
		if [ ! -z "$testresult" ]; then
			return 11
		else
			return 10
		fi
	fi
}

##### Interface configuration

## Add an IPv6 address for given interface
#  $1: Interface 
#  $2: IPv6 address
ifup_ipv6_real() {
	local device=$1
	local address=$2

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		ifupdown_ipv6_usage
		return 1
	fi

	if [ -z "$address" ]; then
		echo $"Missing parameter 'IPv6-address' (arg 2)"
		ifupdown_ipv6_usage
		return 1
	fi

	test_ipv6 || return 2

	testipv6_valid $address || return 2

	if test_interface_status $device; then
		true
	else
			ifconfig $device up

			if ! test_interface_status $device; then
				echo $"Device '$device' enabling didn't work - FATAL ERROR!"
				return 2
			fi
	fi


	# Extract address parts
	local prefixlength_implicit="`echo $address | awk -F/ '{ print $2 }'`"
	local address_implicit="`echo $address | awk -F/ '{ print $1 }'`"

	# Only add if address does not already exist
	test_ipv6_address_exists $device $address_implicit $prefixlength_implicit
	retval=$?
	if [ $retval -lt 10 ]; then
		return 2
	fi

	if [ $retval -eq 11 ]; then
		true
	else
			ifconfig $device add $address || return 2
	fi

	return 0
}


## Remove all IPv6 routes and addresses for given interface
#   cleanup to prevent kernel crashes
#  $1: Interface 
ifdown_ipv6_real_all() {
	local device=$1

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	test_ipv6 || return 2


	# Remove all IPv6 routes through this device (but not "lo")
		if [ "$device" != "lo" ]; then
	        	ip -6 route flush dev $device >/dev/null 2>&1
		fi

	# Remove all IPv6 addresses on this interface
		ip -6 addr flush dev $device >/dev/null 2>&1

	return 0
}


## Remove an IPv6 address on given interface
#  $1: Interface 
#  $2: IPv6 address
ifdown_ipv6_real() {
	local device=$1
	local address=$2

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		ifupdown_ipv6_usage
		return 1
	fi

	if [ -z "$address" ]; then
		echo $"Missing parameter 'IPv6-address' (arg 2)"
		ifupdown_ipv6_usage
		return 1
	fi

	test_ipv6 || return 2

	testipv6_valid $address || return 2


	# Extract address parts
	local prefixlength_implicit="`echo $address | awk -F/ '{ print $2 }'`"
	local address_implicit="`echo $address | awk -F/ '{ print $1 }'`"

	# Only remove, if address exists and is not link-local (prevents from kernel crashing)
	test_ipv6_address_exists $device $address_implicit $prefixlength_implicit
	local retval=$?
	if [ $retval -lt 10 ]; then
		return 2
	fi

	if [ $retval -eq 11 ]; then
			ifconfig $device del $address || return 2
	else
		true
	fi
    
	return 0
}


##### Some address test functions

## Test a given IPv6 address for valid
#  $1: IPv6 address
#  Return code =0:valid  1:not valid  2:general problem
testipv6_valid() {
	local testipv6addr_valid=$1


	if [ -z "$testipv6addr_valid" ]; then
		return 2
	fi

	# Extract parts
	local prefixlength_implicit="`echo $testipv6addr_valid | awk -F/ '{ print $2 }'`"
	local address_implicit="`echo $testipv6addr_valid | awk -F/ '{ print $1 }'`"

	if [ "$EXISTS_ipv6calc" = "yes" ]; then
		if ! ipv6calc --addr2uncompaddr $testipv6addr_valid >/dev/null 2>&1; then
			echo $"Given IPv6 address '$testipv6addr_valid' is not valid"
			return 1
		fi
	else
		# Test for a valid format
		if ! echo "$address_implicit" | egrep -q '^[a-fA-F0-9:\.]*$'; then
			echo $"Given IPv6 address '$testipv6addr_valid' is not valid"
			return 1
		fi
	fi

	# Test for prefix length
	if [ -z "$prefixlength_implicit" ]; then
		if echo "$testipv6addr_valid" | grep "/$"; then
			# Trailing "/", but no value
			echo $"Missing 'prefix length' for given address '$testipv6addr_valid'"
			return 1
		else
			return 0
		fi
	elif [ $prefixlength_implicit -lt 0 -o $prefixlength_implicit -gt 128 ]; then
		echo $"'prefix length' on given address '$testipv6addr_valid' is out of range (0-128)"
		return 1
	fi

	return 0
}




## Test a given IPv4 address for not a private but unicast one
#  $1: IPv4 address
#  Return code =0:ok  1:private or not unicast  2:general problem
testipv4_globalusable() {
	local testipv4addr_globalusable=$1


	if [ -z "$testipv4addr_globalusable" ]; then
		return 2
	fi


	# Test for a globally usable IPv4 address now
		# test 0.0.0.0/8
		ipcalc --network $testipv4addr_globalusable 255.0.0.0   | grep -q "NETWORK=0\.0\.0\.0"     && return 1
		# test 10.0.0.0/8 (private)
		ipcalc --network $testipv4addr_globalusable 255.0.0.0   | grep -q "NETWORK=10\.0\.0\.0"    && return 1
		# test 127.0.0.0/8 (loopback)
		ipcalc --network $testipv4addr_globalusable 255.0.0.0   | grep -q "NETWORK=127\.0\.0\.0"    && return 1
		# test 169.254.0.0/16 (DHCP link local)
		ipcalc --network $testipv4addr_globalusable 255.255.0.0 | grep -q "NETWORK=169\.254\.0\.0"  && return 1
		# test 172.16.0.0/12 (private)
		ipcalc --network $testipv4addr_globalusable 255.240.0.0 | grep -q "NETWORK=172\.16\.0\.0"  && return 1
		# test 192.168.0.0/16 (private)
		ipcalc --network $testipv4addr_globalusable 255.255.0.0 | grep -q "NETWORK=192\.168\.0\.0" && return 1
		# test 224.0.0.0/3 (multicast and reserved, broadcast)
		ipcalc --network $testipv4addr_globalusable 224.0.0.0   | grep -q "NETWORK=224\.0\.0\.0"   && return 1
	
	return 0
}


## Test a given device for status
#  $1: device name
#  Return code =0:UP  1:not UP  2:not exists
test_interface_status() {
	local device=$1

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device'"
		echo $"Usage: ifdown_ipv6to4_all interfacename"
		return 1
	fi

	# Test if device exists
	if ! LC_ALL=C ifconfig $device >/dev/null 2>&1 ; then
		return 2
	fi

	# Test if device is up
	if LC_ALL=C ifconfig $device 2>&1 | grep -q "UP "; then
		return 0
	else
		return 1
	fi
}


## Build 6to4 prefix
#  $1: IPv4 address
# RetVal: 6to4address
# Returncode 0=ok  1=failure  2=general problem
create6to4prefix() {
	local ipv4addr=$1


	local major1="`echo $ipv4addr | awk -F. '{ print $1 }'`"
	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 2
	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
}


##### 6to4 tunneling setup

## Configure 6to4 tunneling up
#  $1: Interface (not needed - dummy)
#  $2: global IPv4 address of local interface
#  $3: IPv6 suffix for 6to4 prefix (optional, default is "1")
# ReturnCodes 0=ok  1=failure  2=general problem
ifup_ipv6to4() {
	local device=$1  # dummy
	local localipv4=$2
	local localipv6to4suffix=$3

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		ifupdown_ipv6to4_usage
		return 1
	fi

	if [ -z "$localipv4" ]; then
		echo $"Missing parameter 'local IPv4 address' (arg 2)"
		ifupdown_ipv6to4_usage
		return 1
	fi

	test_ipv6 || return 2


	# Generate 6to4 address
	local prefix6to4="`create6to4prefix $localipv4`"
	if [ $? -ne 0 -o -z "$prefix6to4" ]; then
		return 2
	fi

	if [ -z "$localipv6to4suffix" ]; then
		local address6to4="${prefix6to4}::1/16"
	else
		local address6to4="${prefix6to4}::${localipv6to4suffix}/16"
	fi

	# Enable general IPv6-over-IPv4 tunneling
	ifup_ipv6_autotunnel

	ifup_ipv6_real sit0 $address6to4	
	if [ $? -ne 0 ]; then
		return 2
	fi

	return 0
}	


## Configure all 6to4 tunneling down
#  $1: Interface (not needed - dummy)
# ReturnCodes 0=ok  1=failure  2=general problem
ifdown_ipv6to4_all() {
	local device=$1  # dummy

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	test_ipv6 || return 2


	# Get all configured 6to4 addresses and delete them
	LC_ALL=C ip addr show dev sit0 | grep inet6 | awk '{ print $2 }' | grep "^2002:" | while read ipv6to4addr; do
		ifdown_ipv6_real sit0 $ipv6to4addr
	done

	# Try to disable general IPv6-over-IPv4 tunneling
	ifdown_ipv6_autotunnel

}	


## Configure 6to4 tunneling down
#  $1: Interface (not needed - dummy)
#  $2: global IPv4 address of local interface
# ReturnCodes 0=ok  1=failure  2=general problem
ifdown_ipv6to4() {
	local device=$1  # dummy
	local localipv4=$2

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$localipv4" ]; then
		echo $"Missing parameter 'local IPv4 address' (arg 2)"
		return 1
	fi

	test_ipv6 || return 2


	# generate 6to4 address
	local prefix6to4="`create6to4prefix $localipv4`"
	echo $"Generated 6to4 prefix '$prefix6to4' from '$localipv4'"
	if [ $? -ne 0 -o -z "$prefix6to4" ]; then
		return 2
	fi

	if [ -z "$localipv6to4suffix" ]; then
		local address6to4="$prefix6to4::1/16"
	else
		local address6to4="${prefix6to4}::${localipv6to4suffix}/16"
	fi

	ifdown_ipv6_real sit0 $address6to4	
	if [ $? -ne 0 ]; then
		return 2
	fi

	# Try to disable general IPv6-over-IPv4 tunneling
	ifdown_ipv6_autotunnel
	if [ $? -ne 0 ]; then
		return 2
	fi

	return 0
}	


##### static tunnel device configuration

## Configure a static tunnel device up
#  $1: Interface 
#  $2: IPv4 address of foreign tunnel
#  $3: Local IPv6 address of a P-t-P tunnel (optional)
ifup_ipv6_tunneldev() {
	local device=$1
	local addressipv4tunnel=$2
	local addressipv6local=$3

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$addressipv4tunnel" ]; then
		echo $"Missing parameter 'IPv4-tunnel address' (arg 2)"
		return 1
	fi

	test_ipv6 || return 2   



		if ! test_interface_status $device; then
			local ttldefault="`sysctl 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 (does not catch IPv4 addresses with leading 0's)
			LC_ALL=C ip tunnel show | grep $addressipv4tunnel | while read dev type tag remote tag local tag ttl rest; do
				local devnew="`echo $dev | sed 's/:$//g'`"
				if [ "$remote" = "$addressipv4tunnel" ]; then
					echo $"Given remote address '$addressipv4tunnel' on tunnel device '$device' is already configured on device '$devnew' - FATAL ERROR!"
					return 2
				fi
			done
			if [ $? -ne 0 ]; then
				return 2
			fi

			ip tunnel add $device mode sit ttl $ttldefault remote $addressipv4tunnel

			# Test, whether "ip tunnel show" works without error
			ip tunnel show $device >/dev/null 2>&1
			if [ $? -ne 0 ]; then
				echo $"Tunnel device '$device' creation didn't work - ERROR!"
				return 2
			fi

			# Test, whether "ip tunnel show" reports valid content
			if ! ip tunnel show $device | grep -q "remote"; then
				echo $"Tunnel device '$device' creation didn't work - ERROR!"
				return 2
			fi

			ifconfig $device up

			if ! test_interface_status $device; then
				echo $"Tunnel device '$device' bringing up didn't work - ERROR!"
				return 2
			fi

			# Set sysctls proper (regardless "default")
			sysctl -w net.ipv6.conf.$device.forwarding=1 >/dev/null
			sysctl -w net.ipv6.conf.$device.accept_ra=0 >/dev/null
			sysctl -w net.ipv6.conf.$device.accept_redirects=0 >/dev/null

			if [ ! -z "$addressipv6local" ]; then
				# Setup P-t-P address
				ifup_ipv6_real $device $addressipv6local
				if [ $? -ne 0 ]; then
					return 2
				fi
			fi
		else
			false
		fi

	return 0
}	


## Configure a static tunnel device down
#  $1: Interface
ifdown_ipv6_tunneldev() {
	local device=$1

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	test_ipv6 || return 2   


	if test_interface_status $device; then
		ifdown_ipv6_real_all $device
	else
		if [ "$device" != "sit0" ]; then
			false
		fi
	fi

	if [ "$device" != "sit0" ]; then
		if ip tunnel | grep -q "^$device:" ; then
				ip tunnel del $device

				if test_interface_status $device; then
					false
				fi
		else												
			false
		fi
	fi

	return 0
}	


## Set IPv6 MTU for a device
#  $1: Interface
#  $2: IPv6 MTU
ipv6_set_mtu() {
	local device=$1
	local ipv6_mtu=$2

	if [ -z "$device" ]; then
		echo $"Missing parameter 'device' (arg 1)"
		return 1
	fi

	if [ -z "$ipv6_mtu" ]; then
		echo $"Missing parameter 'IPv6 MTU' (arg 2)"
		return 1
	fi

	# Check range
	if [ $ipv6_mtu -lt 1280 -o $ipv6_mtu -gt 65535 ]; then
		echo $"Given IPv6 MTU is out of range"
		return 1
	fi

		sysctl -w net.ipv6.conf.$device.mtu=$ipv6_mtu >/dev/null
}