Merge branch 'dns64-vpn' into 'master'

New article: Proying IPv4 traffic via the ungleich VPN

See merge request ungleich-public/ungleich-staticcms!5

content/u/blog/2020-02-18-proxying-ipv4-traffic-via-ungleich-vpn/contents.lr

@@ -0,0 +1,42 @@
+title: Proying IPv4 traffic via the ungleich VPN
+---
+pub_date: 2020-02-18
+---
+author: Timothée Floure
+---
+_hidden: no
+---
+_discoverable: yes
+---
+abstract:
+DNS64 is now available for the ungleich VPN, allowing to reach the IPv4
+world... on an IPv6-only VPN!
+
+---
+body:
+
+We have been offering an [IPv6-capable VPN](https://ungleich.ch/ipv6/vpn/)
+alongside our IPv6-only VPS hosting for a while in order to bring IPv6
+connectivity to customers stuck in the IPv4 world. The service also allows you
+to reach the IPv6-enabled side of global Internet but was not able to connect
+to IPv4-only services (such as [github](https://github.com/)!), which can be
+painful depending on your use-case.
+
+This shortcoming is no more since we recently deployed two
+[DNS64](https://en.wikipedia.org/wiki/IPv6_transition_mechanism#DNS64)
+resolvers available to any VPN user. They will generate a synthetic IPv6
+address for domains lacking an `AAAA` (i.e. IPv6) DNS record, which will in
+turn be routed via our NAT64 gateway. You only have to configure
+`2a0a:e5c0:2:12:0:f0ff:fea9:c451` and `2a0a:e5c0:2:12:0:f0ff:fea9:c45d` as DNS
+servers when you are connected to the VPN: all the details and instructions are
+available on [our
+wiki](https://redmine.ungleich.ch/projects/open-infrastructure/wiki/Ungleich_IPv6_wireguard_VPN#Proxy-all-traffic-via-the-VPN), although it boils down to two lines in your wireguard configuration.
+
+The above means that ungleich now provides a *fully-fledged* VPN! Note, however, that
+direct IPv4 queries (i.e. requests 'bypassing' DNS resolution) won't be routed
+though the VPN.  Full isolation can be achieved using network namespaces as
+described in the [wireguard
+documentation](https://www.wireguard.com/netns/#the-new-namespace-solution).
+Feel free to [join our
+chat](https://redmine.ungleich.ch/projects/open-infrastructure/wiki/CHATting_with_ungleich)
+to discuss such (non-trivial) setup in details!