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0.前言
爱快其实已经支持IPV6了，在Lan口处的设备也能获取到IPv6了。
但是当Openwrt作为二级路由时，我无论怎么设置，都无法让Openwrt Lan口下的设备获取到IPv6。未果，便想到了使用NAT6转发，然后成功了，便在此做个笔记。
2021.12.7 UPDATE
如果你获取 IPv6 前缀为 /60
那么旧方法可以全部抛弃了
我们只需要给 LAN 口分配 /61 到 /63 的前缀就行
因为爱快默认向LAN分发地址的前缀为 /64 ，因为安全原因导致Openwrt 无法继续下发前缀
建议用 /62
这样 Openwrt 的 WAN 就能获取到前缀为 /62 或者 /63 的地址了
然后我们简单设置 下 Openwrt 的 LAN 口
再设置下 WAN6 口
如果没有就创建一个，协议为 “DHCPv6 客户端”，然后防火墙划分至 WAN
搞定，如果获取不到，请确认你的固件是否支持 IPv6，然后重启试试
2021.4.12 UPDATE
请参考openwrt wiki
https://openwrt.org/docs/guide-user/network/ipv6/ipv6.nat6
执行完后全部设备重启+重新连接无线即可
测试
ping 240C::6666 -t
1.准备工作
首先在编译固件时需要勾选 kmod-ipt-nat6 这个包，没有的可以尝试安装（一般来说应该是有的）
#更新源 opkg update #安装kmod-ipt-nat6 opkg install kmod-ipt-nat6
在 “网络-接口” 处，将 “IPv6 ULA 前缀” 的第一个字母改为d
将这个脚本放到 /etc/init.d/nat6，保存好
vim /etc/init.d/nat6
#!/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
}然后启用nat6服务
#添加执行权限 chmod +x /etc/init.d/nat6 #开机启动 /etc/init.d/nat6 enable
在/etc/sysctl.conf中添加这几行
vim /etc/sysctl.conf
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
然后在网络-接口-LAN-IPV6设置勾选通告默认路由
最后在 “网络-防火墙-自定义规则” 中添加以下内容
ip6tables -t nat -I POSTROUTING -s $(uci get network.globals.ula_prefix) -j MASQUERADE
重启
reboot
2.善后工作
由于宽带重拨时，有时候可能会掉v6，可以在Openwrt中设置自动重启
最后去测试一下吧
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