Virtual LAN over NATS

vlan-nats

Disclaimer: This is only a fun experiment. Do not use it for anything serious.

vlan-nats creates a virtual LAN using NATS. Backed by a NATS server (or cluster), vlan-nats can create and run a network interface that is connected to a virtual L2 switch.

vlan-nats is written in entirely in Go. Currently, it works only on Linux. Multicast is not supported.

First, get and build vlan-nats:

$ go get github.com/rapidloop/vlan-nats

Then, on each machine, do:

sudo vlan-nats -n nats://{MY-NATS-SERVER}:4222 &
sudo ip addr add 10.1.0.{CHANGEME} broadcast 10.1.255.255 dev vnats0
sudo ip link set vnats0 up
sudo ip route add 10.1.0.0/16 dev vnats0

You should replace {CHANGEME} with a unique number. The {MY-NATS-SERVER} is the IP or host of a reachable NATS server (all machines must connect to the same NATS cluster).

Congratulations! You now have all your machines reachable on the virtual subnet 10.1.0.0/16. You should be able to ping each other:

$ ip a show vnats0
7: vnats0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
    link/ether 7e:8f:d4:17:2b:0c brd ff:ff:ff:ff:ff:ff
    inet 10.1.0.1/32 brd 10.1.255.255 scope global vnats0
       valid_lft forever preferred_lft forever
    inet6 fe80::7c8f:d4ff:fe17:2b0c/64 scope link tentative dadfailed
       valid_lft forever preferred_lft forever
$ ping 10.1.0.2
PING 10.1.0.2 (10.1.0.2) 56(84) bytes of data.
64 bytes from 10.1.0.2: icmp_seq=1 ttl=64 time=1.70 ms
64 bytes from 10.1.0.2: icmp_seq=2 ttl=64 time=1.60 ms
^C
--- 10.1.0.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1003ms
rtt min/avg/max/mdev = 1.603/1.654/1.706/0.065 ms
$

Cool!

To cleanup, just sudo pkill vlan-nats. The interface is not persisted.

How It Works

vlan-nats creates a TAP interface. All broadcast frames from the interface are published to the NATS topic vlan.{ID} and unicast frames are published to vlan.{ID}.{DST_ETHADDR}. The process subscribes to vlan.{ID} and vlan.{ID}.{OWN_ETHADDR} and writes out any received frames into the TAP interface.

Windows and OS X do not natively support TAP devices, but (free) 3rd party drivers are available.

Things To Try Out

• Windows and OS X can be supported with 3rd party TAP drivers.
• Run a DHCP server instead of assigning static IPs.
• Use a TLS-enabled, authenticated, public NATS server – like a VPN!