DHCP With Ipv6 Tunnel

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I’m completely confused here and I’m hoping someone here has a setup they’re willing to share, or help me configure things on my end.

My connectivity is through Comcast, who unfortunately, does not offer ipv6
in my area. My connection goes like this:
Comcast -> Motorola Surfboard Cable Router -> CentOS 6.5 server

The CentOS server is multi-homed and manages the internal 192.168.x.x network by offering DHCP and firewall service (NATting and others.) DNS
lookups are going to Comcast’s servers.

I have an IPV6 tunnel through Hurricane Electric (www.tunnelbroker.net). The tunnel is configured and is up and running on the CentOS server. I can ping several IPV6 addresses from it just fine:

ping6 -n ipv6.google.com PING ipv6.google.com(2607:f8b0:400f:801::1006) 56 data bytes
64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=1 ttlS time9 ms
64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=2 ttlS time9 ms
64 bytes from 2607:f8b0:400f:801::1006: icmp_seq=3 ttlS time6 ms
^C
— ipv6.google.com ping statistics –

5 thoughts on - DHCP With Ipv6 Tunnel

  • I too am interested in this. I use a tunnel through Sixxs and I assign IPv6
    addresses using radvd. I have radvd, aiccu, DNS, DHCP (v4 only) and IPv6
    routing all running on a CentOS 6.5 server. All of my servers and workstations are able to ping6 to outside targets, and anything with a browser installed can open ipv6.google.com.

    So far I have figured out that you have to run TWO instances of DHCP.

  • As long as you run a router advertisement daemon clients will self-assign routable addresses, you don’t really need DHCPv6 if you are also running DHCPv4, you can set DNS (even an IPv6 DNS server) or any other configuration using the DHCPv4 daemon.

  • That’s the thing Mark, configuring it is where I’m stuck. I’m unsure of what addresses I’m supposed to be using as the prefixes that Hurricane Electric gives me for /64 and /48, are different from the tunnel’s endpoint address. At least I think I’m reading it right from the tunnel’s information page.

    So when I use those to configure dhcpd6.conf and try to run (the second)
    dhcpd, it tells me it hasn’t been configure to use any interface. Even though I’m telling it to on the command line I’m using to test the configuration. Regardless of what interface I tell it to use, it fails.

    So I was hoping someone has a working config that works with HE’s setup.

  • So an he.net tunnel has a /64 used as a point-to-point network which is what runs on the IPv4 tunnel, and either a single /64 that you route for your internal subnet, or a /48 which allows you to carve out 65535 subnets of /64 each, equivalent addressing to an IPv4 /16 where each address is NATting for an entire network itself.

    So pick the first /64 subnet inside your /48 allocated to you and route that internally and set that up in your router advertisement daemon.

    For example if your point-to-point is
    2001:470:AAAA:1234::1/64 (HE.net) — 2001:470:AAAA:1234::2/64 (your router)

    and your routed subnets are out of 2001:470:BBBB:1234::/48

    2001:470:BBBB:1234::/64
    2001:470:BBBB:1235::/64
    …

    Then you’d have say 2001:470:BBBB:1234::1/64 on one router interface and advertise 2001:470:BBBB:1234::/64

  • Thanks for the explanation Mark. I will try that when I get home and get on my test setup. I’ll report back with my findings or more inquiries.