config as an exit of "IPv6 over IPv4 tunnel"

[Matthew Seaman]

Hashimoto wrote:
> Can I configure FreeBSD as an exit of "IPv6 over IPv4 tunnel"?
> 
> Let me explain it in detail.
> Both hostA and hostB have global IPv4 address.
> And hostA has global IPv6 address.
> I have installed FreeBSD 7.0 on both hostA and hostB.
> Then, I want to config "IPv6 over IPv4 tunnel" from hostB to hostA.
> Is it possible?
> 

Yes, absolutely.  I have a similar configuration for my IPv6 connectivity.
There are some alternatives (stf(4), faith(4)), but this is based I what
I have.

This is mostly in terms of what you'ld add to /etc/rc.conf on HostB --
HostA will be similar, but addresses will be reversed in the obvious
places.

i) Create a gif(4) interface and configure the endpoints:

gif_interfaces="gif0"
gifconfig_gif0="hostB-ipv4-number hostA-ipv4-number"

ii) Enable IPv6 on HostB -- I'm assuming you've assigned a /64 
net block to HostB (perhaps a tad excessive, but pretty much the
default for an allocation of a chunk of IPv6 address space.) Adjust
the prefixlen to suit.

ipv6_enable="YES"
ipv6_defaultrouter="-interface gif0"
ipv6_default_interface="gif0"
ipv6_ifconfig_gif0="1234:5678:9abc:def0::1 prefixlen 64"

iii) Settings on HostA are slightly different -- HostA has to be a
router, and it only wants to route the HostB block via the gif(4)
tunnel:

ipv6_enable="YES"
ipv6_defaultrouter="hostA-ipv6-gateway-address"
ipv6_gateway_enable="YES"

ipv6_static_routes="hostB"
ipv6_route_hostB="1234:5678:9abc:def0:: -prefixlen 64 -interface gif0"

iv) That should be everything you need to get point to point connectivity 
working.  Note: it's pretty easy now to make HostB an IPv6 router and
assign IPv6 addresses to anything on the same local subnet as HostB.
In fact, you can use rtadvd(8) on HostB to make that automatic:

ipv6_network_interfaces="auto"
ipv6_prefix_em0="1234:5678:9acb:def0"
rtadvd_enable="YES"
rtadvd_interfaces="em0"

Then just run rtsol(8) on all the other machines that will use HostB as
their IPv6 gateway.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
                                                  Kent, CT11 9PW

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