openwrt使用tayga/totd实现NAT64/DNS64
目前有一些智能家居方案如Thread在使用ipv6进行组网一种基于Thread的IPv6智能家居解决方案，但ipv6 ISP环境部署还未完善，所以很多方案选择使用ipv4服务器与ipv6终端通信，这需要在网络拓扑中搭建一个具有NAT64/DNS64功能的边缘路由器。
NAT64/DNS64功能拓扑如下图：
下面是博主使用openwrt进行搭建NAT64/DNS64功能的例子。
1.配置tayga实现NAT64
(1)下载tayga
opkg update
opkg install tayga
(2)配置/etc/config/network文件
config globals 'globals'
option ula_prefix 'ddbe:48ec:56c6::/48'
config interface 'nat64'
option proto 'tayga'
option ifname 'tayga-nat64'
option ipv4_addr '192.168.64.1'
option prefix 'ddbe:48ec:56c6:1111::/96' #这里注意前缀前64位不能与br-lan相同
option dynamic_pool '192.168.64.0/24'
option accept_ra '0'
option send_rs '0'
openwrt使用ula_prefix作为本地ipv6前缀，一般为48位前缀，br-lan一般为64位前缀，则tayga-nat64的前缀前64位不得与br-lan相同，否则nat64会找不到路由表
root@GL-X750:/# route -A inet6
Kernel IPv6 routing table
Destination Next Hop Flags Metric Ref Use Iface
ddbe:48ec:56c6:10::/64 :: U 1024 0 0 br-lan
ddbe:48ec:56c6:1111::/96 :: U 1024 0 0 tayga-nat64
ddbe:48ec:56c6::/48 :: !n 2147483647 0 0 lo
(3)配置/etc/config/firewall
config zone
option name 'lan'
list network 'lan'
list network 'nat64' #添加nat64
option input 'ACCEPT'
option output 'ACCEPT'
option forward 'ACCEPT
(4)重启network与firewall
/etc/init.d/network restart
/etc/init.d/firewall restart
(5)测试tayga功能
root@GL-X750:/# ping6 ddbe:48ec:56c6:1111::8.8.8.8
PING ddbe:48ec:56c6:1111::8.8.8.8 (ddbe:48ec:56c6:1111::808:808): 56 data bytes
64 bytes from ddbe:48ec:56c6:1111::808:808: seq=0 ttl=46 time=60.722 ms
64 bytes from ddbe:48ec:56c6:1111::808:808: seq=2 ttl=45 time=69.222 ms
64 bytes from ddbe:48ec:56c6:1111::808:808: seq=3 ttl=45 time=46.831 ms
64 bytes from ddbe:48ec:56c6:1111::808:808: seq=4 ttl=46 time=44.560 ms
64 bytes from ddbe:48ec:56c6:1111::808:808: seq=5 ttl=45 time=50.169 ms
^C
--- ddbe:48ec:56c6:1111::8.8.8.8 ping statistics ---
6 packets transmitted, 5 packets received, 16% packet loss
round-trip min/avg/max = 44.560/54.300/69.222 ms
使用ping6通8.8.8.8证明nat64功能成功
2.2配置totd实现DNS64
(1)下载totd
opkg update
opkg install totd
openwrt1806已经把totd删掉，如果发现源里没有该软件包，可从https://github.com/dengxinfa/openwrt-totd.git里clone自行编译。
(2)修改配置文件/etc/totd.conf
; Totd sample configuration file
; you can have multiple forwarders, totd will always prefer
; forwarders listed early and only use forwarders listed later
; if the first ones are unresponsive.
forwarder 8.8.8.8 port 53 #dns服务器
; you can have multiple prefixes or even no prefixes at all
; totd uses them in round-robin fashion
prefix ddbe:48ec:56c6:1111:: #ipv6前缀，与nat64配置成一样
; the port totd listens on for incoming requests
port 5353 #本地totd监听端口
; the pidfile to use (default: /var/run/totd.pid)
pidfile /var/run/totd.pid
; interfaces totd listens on (UDP only for now and not on Linux)
; If left out totd will only open wildcard sockets.
; interfaces lo br0
; 6to4 reverse lookup
; stf
(3)开启totd
/etc/init.d/totd enable
/etc/init.d/totd restart
(4)配置/etc/config/dhcp
config dnsmasq
option domainneeded '1'
option boguspriv '1'
option filterwin2k '0'
option localise_queries '1'
option rebind_protection '1'
option rebind_localhost '1'
option local '/lan/'
option domain 'lan'
option expandhosts '1'
option nonegcache '0'
option authoritative '1'
option readethers '1'
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.auto'
option nonwildcard '1'
option localservice '1'
list server '127.0.0.1#5353' #配置上流dns服务器为totd的监听端口
option noresolv '1'
config dhcp 'lan'
option interface 'lan'
option start '100'
option limit '150'
option leasetime '12h'
option force '1'
option dhcpv6 'server'
option ra 'server'
option ra_default '1'
option ra_management '1'
重启dhcp
/etc/init.d/odhcp restart
/etc/init.d/dnsmasq restart
(5)测试
使用win7电脑连接openwrt路由器lan口，配置win7只开启ipv6
发现ipv6连接显示internet，证明openwrt中ipv6可使用。
在CMD中使用ping -6命令ping通baidu.com
发现能ping -6通baidu.com，即使用ipv6接通ipv4的baidu.com，证明NAT64/DNS64功能成功。