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Mani Varma Indukuri avatar Server

Unable to reach WAN from LAN host on IPv6

ru flag
Mani Varma Indukuri

In my router, I have 2 interfaces enp1s0 (assumed as WAN) and enp4s0(assumed as LAN). I connected a LAN host and a WAN host. I can ping from LAN host to WAN port of the router but not to the gateway of WAN. The setting is as follows :

  • LAN host IP : 8888::5/64
  • LAN gateway IP (router's enp4s0) : 8888::1/64
  • WAN port IP (router's enp1s0) : 2401:fb00:0:1ff::1fd/64
  • WAN gateway IP : 2401:fb00:0:1ff::1fc/64

IPv6 forwarding is enabled in /etc/sysctl.conf i.e net.ipv6.conf.all.forwarding=1 and restarted the network service.

/proc/sys/net/ipv6/conf/enp1s0/forwarding = 1
/proc/sys/net/ipv6/conf/enp4s0/forwarding = 1
/proc/sys/net/ipv6/conf/default/forwarding = 1
/proc/sys/net/ipv6/conf/all/forwarding = 1

Ping happens from LAN host to LAN gateway and WAN port of router. Default route is there in router to reach WAN gateway. But still I can't access WAN gateway from LAN host. Any help would be appreciated.

tcpdump on router WAN port(enp1s0) is when ping from 8888::5 to 2401:fb00:0:1ff::1fc runs.

11:40:26.986609 IP6 8888::5 > 2401:fb00:0:1ff::1fc: ICMP6, echo request, seq 632, length 64
11:40:27.597211 IP6 2401:fb00:0:1ff::1fd.35373 > 2401:fb00:0:1ff::1fc.domain: 41163+ A? relay-4a21c05c.net.anydesk.com. (48)
11:40:27.601687 IP6 2401:fb00:0:1ff::1fc > 2401:fb00:0:1ff::1fd: ICMP6, destination unreachable, unreachable port, 2401:fb00:0:1ff::1fc udp port domain, length 104
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vidarlo avatar
ar flag
vidarlo
Why do you use 8888::/64? It's not an allocated adress for *any* purpose. Your setup won't work with 8888::/64 adresses anyway.
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Ron Maupin avatar
us flag
Ron Maupin
You seem to be using invalid IPv6 addressing. For example, `888::/64`, is in the RESERVED IPv6 address space and should not be use. For the Internet, you use Global addressing in the `2000::/3` address space. For traffic that never goes on the Internet, you use ULA addressing (locally assigned in the `fd00::/8 space but the next 40 bits must be randomly chosen).
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Mani Varma Indukuri avatar
ru flag
Mani Varma Indukuri
I thought 8888::/64 is global ipv6 address. When I added SNAT rule to change source IP of any incoming packet to IP of WAN port in NF tables, it worked. I can ping web on IPv6. If 8888::/64 is invalid addressing, why is it working ?
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