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Chris Metcalf

specialization is for insects

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I spent far too long trying to figure this out myself, so hopefully this will help somebody else.

Snoqualmie Tunnel

There are a ton of awesome platforms out there, such as Tropo’s IVR and SMS technology, that interact via your code via a service or script that provide. Developing against them, however, is a pain in the ass since you need your script or API to be externally accessible on the web, and you can’t always hang a port to your development machine out on the public Internet.

Some services such as Tunnlr will (for a fee) help you set up a web-accessible tunnel back to your development machine. However, if you have a colo or VPS available, you can easily set that up yourself for free using the following SSH command:

-g Allows remote hosts to connect to the port you create
-n Redirect stdin to /dev/null 
-N Just set up the tunnel, don't launch a shell
-t Force pseudo-tty
-R Set up a port on the remote machine that tunnels back to a local port
$REMOTE_PORT The port number you'll connect to remotely
$LOCAL_PORT Your local HTTP port to Apache, Thin, Rack, whatever

Make sure you poke a hole in your firewall remotely for $REMOTE_PORT. Another key discovery for me was to add the following to my /etc/ssh/sshd_config:

# For remote SSH tunnels
GatewayPorts yes

That tells SSHD to allow remote hosts to connect to your -R forwarded ports.


Photo from jhf’s CC-licensed Flickr stream