Added README.md

README.md

+# docker-nat66
+Docker-nat66 is a daemon managing IPv6 port forwarding for Docker containers. It listens to the docker daemon socket for new containers and adjusts Linux netfilter IPv6 tables according to exposed ports.
+
+With these IPv6 port-forwarding rules place, the container is accessible using IPv6 the same way as it is using the IPv4 port-forwarding managed by the Docker daemon.
+
+## Getting docker-nat66
+Docker-nat66 code is written in Go and available on GitHub under Apache licence. To download and build the code (you need the Golang framework):
+````
+$ git clone https://github.com/bstevant/docker-nat66.git
+$ make
+````
+An initial release [0.1](https://github.com/bstevant/docker-nat66/releases/tag/0.1) is available if you want a pre-build binary.
+
+**DISCLAIMER: This is an early-released code, intended for debugging and getting feedbacks. This code not ready for production. Use at your own risk !**
+
+## Using docker-nat66
+
+### Docker daemon
+Your local Docker should allow IPv6 networking for hosted containers. The Docker daemon should run with the following 2 options:
+````
+dockerd --ipv6 --fixed-cidr-v6=<Docker IPv6 prefix>
+````
+The Docker IPv6 prefix is a /64 prefix used to assign IPv6 addresses to the containers. See the [Docker IPv6 Networking Guide](https://docs.docker.com/engine/userguide/networking/default_network/ipv6/) for more informations.
+
+**We strongly recommend to use as Docker IPv6 prefix an Unicast-Local-Address (RFC 4193) prefix, instead of `2001:db8::/16` or any fancy hexspeak IPv6 prefix. To get your own /48 prefix, just go to this [IPv6 ULA Prefix generator](http://unique-local-ipv6.com/).**
+
+### `iptables` tools
+Docker-nat66 requires the `ip6tables` tool to interact with the netfilter IPv6 tables. This tool should be installed on your Linux system.
+
+### Start the daemon
+Docker-nat66 requires 2 arguments to be run:
+````
+docker-nat66 -dev <egress interface> -prefix <Docker IPv6 prefix>
+````
+The **egress interface** is the network interface receiving incoming requests to your containers. This interface should be connected to an IPv6-enabled network (e.g. it should have a global IPv6 address).
+
+The **Docker IPv6 prefix** is the prefix used for container addressing, as explained above. 
+
+The daemon requires to be started as root:
+````
+# ./docker-nat66 -dev eth0 -prefix fdfd:5898:4917:1:/64
+````
+Once the docker-nat66 daemon is started, it initializes NAT66 in the netfilter tables and listens to docker events to add/remove port-forwarding rules as containers are started or terminated.
+
+### Example
+````
+# ./docker-nat66 -dev=eth0 -prefix=fdfd:5898:4917:1:/64
+2016/10/06 14:23:42 NAT66 set postrouting: /sbin/ip6tables -t nat -A POSTROUTING -o eth0 -s fdfd:5898:4917:1:/64 -j MASQUERADE
+````
+This first rule is mandatory for translating outgoing packets from your containers.
+
+In another terminal, we start a `redis` container. Notice we first indicate the port to be exposed, but not the port to be mapped with.
+````
+$ docker run -ti redis -p 6379
+````
+The docker-nat66 terminal automatically adjusts the NAT66 rules to forward incoming packets to the mapped port to the container port and address:
+````
+2016/10/06 14:23:48 NAT66 add portfwd: /sbin/ip6tables -t nat -A PREROUTING -i eth0 -p tcp --dport 32770 -j DNAT --to-destination [fdfd:5898:4917:1:0:242:ac11:2]:6379
+````
+Your `redis` container is now reachable using the IPv6 address configured on `eth0` and port `32770`
+
+When the `redis` container is terminated, the port-forwarding rule is removed from the table:
+````
+2016/10/06 14:23:54 NAT66 del portfwd: /sbin/ip6tables -t nat -D PREROUTING -i eth0 -p tcp --dport 32770 -j DNAT --to-destination [fdfd:5898:4917:1:0:242:ac11:2]:6379
+````
+When you explicitely give a port to be mapped for the container, it is taken into account in the port-forwarding rule:
+````
+$ docker run -ti redis -p 2356:6379
+````
+Docker-nat66 outputs: (notice the change for the `--dport` argument)
+````
+2016/10/06 14:24:14 NAT66 add portfwd: /sbin/ip6tables -t nat -A PREROUTING -i eth0 -p tcp --dport 2356 -j DNAT --to-destination [fdfd:5898:4917:1:0:242:ac11:2]:6379
+````
+When the docker-nat66 daemon is terminated, it should remove any residing NAT66 rules it inserted and the global NAT66 configuration.
+
+## Feedbacks and Bug Reports
+As this code is in its very early stage, any feedback is warmly welcome. I am very interested in discussing how this tool can be adapted for Docker production environments where IPv6 is deployed and used.
+
+I am committed to promoting IPv6 usage for more than 10 years and I will really appreciate that the Docker community also embraces IPv6. I hope this tool will help!