目前的设置：使用IPv4和IPv6的OpenVPN服务器：
[...] port 1234 proto udp6 dev tun server 10.9.8.0 255.255.255.0 server-ipv6 2001:1af8:3100:a00a:0021:a:b:0000/112 client-to-client [...] 客户通过CCD获取IP：
ifconfig-ipv6-push 2001:1af8:3100:a00a:21:a:b:0006 ifconfig-push 10.9.8.6 10.9.8.5
在一个侧面说明：这似乎只适用于Linux（包括在Debian 2.2 oVPN）; IPv6线路破坏了Tunnelblick（OS X）和Windows（=>客户端甚至不能通过IPv4 ping对方）的所有内容。
连接的客户端获得两个IP地址; 一个IPv4地址和一个IPv6地址：
10.9.8.6,pc1,::ffff:212.3.2.1,Fri Dec 19 23:26:02 2014 2001:1af8:3100:a00a:21:a:b:6,pc1,::ffff:212.3.2.1,Fri Dec 19 23:21:22 2014 10.9.8.102,pc2,2001:1af8:b:a00a:21::4,Fri Dec 19 23:25:34 2014 2001:1af8:3100:a00a:21:a:b:102,pc2,2001:1af8:b:a00a:21::4,Fri Dec 19 23:06:11 2014
从VPN服务器Ping IPv6地址（即：2001：1af8：3100：a00a：21：a：b：102）工作正常。 客户之间的Ping不起作用：
pc1 ~ # ping6 2001:1af8:3100:a00a:21:a:b:102 PING 2001:1af8:3100:a00a:21:a:b:102 (2001:1af8:3100:a00a:21:a:b:102): 56 data bytes 64 bytes from 2a02:578:854f:100:7271:a:1b11: Destination unreachable: Address unreachable 64 bytes from 2a02:578:854f:100:7271:a:1b11: Destination unreachable: Address unreachable 64 bytes from 2a02:578:854f:100:7271:a:1b11: Destination unreachable: Address unreachable ^C--- 2001:1af8:3100:a00a:21:a:b:102 ping statistics --- 5 packets transmitted, 0 packets received, 100% packet loss
但是IPv4的作品：
pc1 ~ # ping 10.9.8.102 PING 10.9.8.102 (10.9.8.102): 56 data bytes 64 bytes from 10.9.8.102: icmp_seq=0 ttl=64 time=32.217 ms 64 bytes from 10.9.8.102: icmp_seq=1 ttl=64 time=31.641 ms ^C--- 10.9.8.102 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max/stddev = 31.641/31.929/32.217/0.288 ms
我错过了什么？ iptables？ 一些sysctl选项？ 谢谢。
vpn-server # cat /proc/sys/net/ipv6/conf/all/forwarding 1
跟踪（直到我自己的IPv6地址）：
pc1 ~ # traceroute6 2001:1af8:3100:a00a:21:a:b:102 traceroute to 2001:1af8:3100:a00a:21:a:b:102 (2001:1af8:3100:a00a:21:a:b:102), 30 hops max, 80 byte packets 1 2a02:578:854f:100:7271:bcff:f:1b11 (2a02:578:854f:100:7271:bcff:f:1b11) 3008.038 ms !H 3008.020 ms !H 3007.985 ms !H pc1 ~ #
路线：
pc1 ~ # ip -6 route show 2001:1af8:3100:a00a::/64 dev eth0 proto kernel metric 256 expires 51sec mtu 1492 advmss 1432 hoplimit 0 2001:1af8:3100:a00a::/64 dev wlan0 proto kernel metric 256 expires 51sec mtu 1492 advmss 1432 hoplimit 0 2001:1af8:3100:a00a::/64 dev tun0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 2a02:578:854f:100::/64 dev eth0 proto kernel metric 256 expires 7177sec mtu 1492 advmss 1432 hoplimit 0 2a02:578:854f:100::/64 dev wlan0 proto kernel metric 256 expires 7177sec mtu 1492 advmss 1432 hoplimit 0 fe80::/64 dev eth0 proto kernel metric 256 mtu 1492 advmss 1432 hoplimit 0 fe80::/64 dev wlan0 proto kernel metric 256 mtu 1492 advmss 1432 hoplimit 0 fe80::/64 dev tun0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0 default via fe80::3631:c4ff:fe3d:eac2 dev eth0 proto kernel metric 1024 expires 1777sec mtu 1492 advmss 1432 hoplimit 255 default via fe80::3631:c4ff:fe3d:eac2 dev wlan0 proto kernel metric 1024 expires 1777sec mtu 1492 advmss 1432 hoplimit 255