ref: 31feae5356ede7652f9133dc9211245270559175 vpn-documentation/IPV6.md -rw-r--r-- 2.0 KiB
31feae53François Kooman initial document for IPv6 2 months ago



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 on how to configure public IPv6 addresses in your VPN server as well as the [firewall](these 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. 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!