31feae5356ede7652f9133dc9211245270559175 — François Kooman 1 year, 10 months ago fefa8a6
initial document for IPv6
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# IPv6

The VPN server software supports both IPv4 and IPv6. We've reached a point 
in the "evolution" of the Internet that IPv4 NAT is unavoidable, but for IPv6
there is no excuse to issue proper public IPv6 addresses to the VPN clients.

By default the VPN server installation will *also* perform NAT for IPv6 
traffic and set some less than optimal configuration parameters. 

This is only meant for *testing*. For production you SHOULD switch to public 
IPv6 addresses for your VPN clients!

As already mentioned in other places in the documentation, your VPN server 
MUST have static IPv4 and IPv6 address configurations.

## IPv6 Routing

IPv6 routing can be, and is, by default enabled in `/etc/sysctl.d/70-vpn.conf`:

net.ipv4.ip_forward = 1
net.ipv6.conf.all.forwarding = 1
# allow RA for IPv6 which is disabled by default when enabling IPv6 forwarding 
# **REMOVE** for static IPv6 configurations!
net.ipv6.conf.all.accept_ra = 2

For production you MUST remove the `net.ipv6.conf.all.accept_ra` line as you'll
be using static IPv6 addresses and thus not need this, so the only contents
MUST be:

net.ipv4.ip_forward = 1
net.ipv6.conf.all.forwarding = 1

## Routed IPv6 Prefix

The easiest, and best way is to have a public IPv6 prefix routed to the public
IPv6 address of your VPN server. 

See [Public Addresses](PUBLIC_ADDR.md) on how to configure public IPv6 
addresses in your VPN server as well as the 
configuration when using public IP addresses.

## NDP Proxy

As a last resort you can use "NDP Proxying".


## Disabling IPv6

If you want to disable IPv6, because your VPN server does not have an IPv6 
connection, you can do so as documented 
[here](FIREWALL.md#reject-ipv6-client-traffic). Technically this does not 
disable IPv6, but drop the IPv6 packets as soon as possible as to not result in
any delays when attempting to services that have native IPv6 support.

IPv6 can currently NOT be fully disabled in the VPN service!