Previously, I used the built-in NAPT66 of Padavan to implement IPv6 forwarding. Recently, I started using Lean's LEDE, and the method of implementing NAT6 is different.
Solution A#
Disable Source Filter#
After SSH connection, execute:
uci set network.wan6.sourcefilter=0
uci commit network
ifup wan6
Set IPv6 ULA Prefix#
Open "Network" - "Interfaces" - "Global Network Options" - "IPv6 ULA Prefix" and change the first character "f" to "d".
Set DHCPv6 Server for LAN#
Open "Network" - "Interfaces" - "LAN" - "DHCP Server" - "IPv6 Settings" and check "Always announce default route".
Add NAT6 Rule#
Open "Network" - "Firewall" - "Custom Rules" and add at the end:
ip6tables -t nat -A POSTROUTING -o eth0.2 -j MASQUERADE
Replace eth0.2 with the name of the WAN6 interface.
Restart#
Restart and test.
If you encounter a situation where you cannot connect to IPv6 after startup, manually restart the firewall.
Solution B#
Set IPv6 ULA Prefix#
Open "Network" - "Interfaces" - "Global Network Options" - "IPv6 ULA Prefix" and change the first character "f" to "d".
Set DHCPv6 Server for LAN#
Open "Network" - "Interfaces" - "LAN" - "DHCP Server" - "IPv6 Settings" and check "Always announce default route".
Create NAT6 Service Script#
Edit "/etc/init.d/nat6" with the following content:
#!/bin/sh /etc/rc.common
# NAT6 init script for OpenWrt // Depends on package: kmod-ipt-nat6
START=55
# Options
# -------
# Use temporary addresses (IPv6 privacy extensions) for outgoing connections? Yes: 1 / No: 0
PRIVACY=1
# Maximum number of attempts before this script will stop in case no IPv6 route is available
# This limits the execution time of the IPv6 route lookup to (MAX_TRIES+1)*(MAX_TRIES/2) seconds. The default (15) equals 120 seconds.
MAX_TRIES=15
# An initial delay (in seconds) helps to avoid looking for the IPv6 network too early. Ideally, the first probe is successful.
# This would be the case if the time passed between the system log messages "Probing IPv6 route" and "Setting up NAT6" is 1 second.
DELAY=5
# Logical interface name of outbound IPv6 connection
# There should be no need to modify this, unless you changed the default network interface names
# Edit by Vincent: I never changed my default network interface names, but still I have to change the WAN6_NAME to "wan" instead of "wan6"
WAN6_NAME="wan6"
# ---------------------------------------------------
# Options end here - no need to change anything below
boot() {
[ $DELAY -gt 0 ] && sleep $DELAY
logger -t NAT6 "Probing IPv6 route"
PROBE=0
COUNT=1
while [ $PROBE -eq 0 ]
do
if [ $COUNT -gt $MAX_TRIES ]
then
logger -t NAT6 "Fatal error: No IPv6 route found (reached retry limit)" && exit 1
fi
sleep $COUNT
COUNT=$((COUNT+1))
PROBE=$(route -A inet6 | grep -c '::/0')
done
logger -t NAT6 "Setting up NAT6"
WAN6_INTERFACE=$(uci get "network.$WAN6_NAME.ifname")
if [ -z "$WAN6_INTERFACE" ] || [ ! -e "/sys/class/net/$WAN6_INTERFACE/" ] ; then
logger -t NAT6 "Fatal error: Lookup of $WAN6_NAME interface failed. Were the default interface names changed?" && exit 1
fi
WAN6_GATEWAY=$(route -A inet6 -e | grep "$WAN6_INTERFACE" | awk '/::\/0/{print $2; exit}')
if [ -z "$WAN6_GATEWAY" ] ; then
logger -t NAT6 "Fatal error: No IPv6 gateway for $WAN6_INTERFACE found" && exit 1
fi
LAN_ULA_PREFIX=$(uci get network.globals.ula_prefix)
if [ $(echo "$LAN_ULA_PREFIX" | grep -c -E "^([0-9a-fA-F]{4}):([0-9a-fA-F]{0,4}):") -ne 1 ] ; then
logger -t NAT6 "Fatal error: IPv6 ULA prefix $LAN_ULA_PREFIX seems invalid. Please verify that a prefix is set and valid." && exit 1
fi
ip6tables -t nat -I POSTROUTING -s "$LAN_ULA_PREFIX" -o "$WAN6_INTERFACE" -j MASQUERADE
if [ $? -eq 0 ] ; then
logger -t NAT6 "Added IPv6 masquerading rule to the firewall (Src: $LAN_ULA_PREFIX - Dst: $WAN6_INTERFACE)"
else
logger -t NAT6 "Fatal error: Failed to add IPv6 masquerading rule to the firewall (Src: $LAN_ULA_PREFIX - Dst: $WAN6_INTERFACE)" && exit 1
fi
route -A inet6 add 2000::/3 gw "$WAN6_GATEWAY" dev "$WAN6_INTERFACE"
if [ $? -eq 0 ] ; then
logger -t NAT6 "Added $WAN6_GATEWAY to routing table as gateway on $WAN6_INTERFACE for outgoing connections"
else
logger -t NAT6 "Error: Failed to add $WAN6_GATEWAY to routing table as gateway on $WAN6_INTERFACE for outgoing connections"
fi
if [ $PRIVACY -eq 1 ] ; then
echo 2 > "/proc/sys/net/ipv6/conf/$WAN6_INTERFACE/accept_ra"
if [ $? -eq 0 ] ; then
logger -t NAT6 "Accepting router advertisements on $WAN6_INTERFACE even if forwarding is enabled (required for temporary addresses)"
else
logger -t NAT6 "Error: Failed to change router advertisements accept policy on $WAN6_INTERFACE (required for temporary addresses)"
fi
echo 2 > "/proc/sys/net/ipv6/conf/$WAN6_INTERFACE/use_tempaddr"
if [ $? -eq 0 ] ; then
logger -t NAT6 "Using temporary addresses for outgoing connections on interface $WAN6_INTERFACE"
else
logger -t NAT6 "Error: Failed to enable temporary addresses for outgoing connections on interface $WAN6_INTERFACE"
fi
fi
exit 0
}
Then use the following command to add execute permission and enable startup.
chmod +x /etc/init.d/nat6
/etc/init.d/nat6 enable
Enable IPv6 Forwarding#
Modify the "/etc/sysctl.conf" file and edit or add the following content:
net.ipv6.conf.default.forwarding=2
net.ipv6.conf.all.forwarding=2
net.ipv6.conf.default.accept_ra=2
net.ipv6.conf.all.accept_ra=2
Add Forwarding Rule#
Open "Network" - "Firewall" - "Custom Rules" and add at the end:
ip6tables -t nat -I POSTROUTING -s $(uci get network.globals.ula_prefix) -j MASQUERADE
Restart the Router#
After that, NAT6 will take effect. The parameters in the NAT6 service script header can be customized as needed.