localtunnel

localtunnel

Expose yourself behind NAT or Firewall to the World!

Compatibility

Both server and client are compatible with Node.JS version of localtunnel.

Features

• Show your work to anyone
• Use the API to test webhooks
• Test your UI in cloud browsers

How it works

         +--------------------+
         | Localtunnel Server |
         |--------------------|         +----------+
         | Backend | Frontend |<--------+TCP Client|
         +---------+----------+         +----------+
            ^  ^^
            |  ||
            |  ||
     Control|  ||Proxy
  Connection|  ||Connections
            |  ||
         +--+--++-------------+         +----------+
         | Localtunnel Client +-------->|TCP Server|
         +--------------------+         +----------+

In a nutshell, localtunnel consists of two components. A server and a client. The server uses express to listen for incoming requests. These requests can either be from a connecting client that wishes to expose its local port to the public net or a client wishing to connect to an already established service at a subdomain.

When a request comes in from the localtunnel client component, it makes a request to https://thelocaltunnelserver/?new and localtunnel server fires up a new TCP server on a randomly generated port greater than 1023 (non-privileged).

The server then returns this randomly generated port to the localtunnel client and gives the client 5 seconds to connect. If the localtunnel client does not establish a connection to the TCP port within 5 seconds, the server is closed and the localtunnel client will have to reconnect to try again.

If the localtunnel client is able to connect to the localtunnel server’s randomly generated TCP port, by default it opens 10 TCP sockets to the server. These connections are held open, even if no data is being transferred. The localtunnel client then waits for requests to come in over any of these 10 TCP sockets. When a request comes in, it is piped to a TCP client that connects to localhost for the desired service.

In order to expose the localtunnel client’s local service to the web, the localtunnel server waits for requests to come in on the subdomain chosen by the localtunnel client. If it matches the subdomain of a currently connected client, the localtunnel server proxies the request to one (or more) of the 10 TCP sockets being held open by the localtunnel client.

Building project

Get the package.

go get -u github.com/bleenco/localtunnel

cd into directory.

cd $GOPATH/src/github.com/bleenco/localtunnel

Install tools.

make get_tools

Install dependencies.

make install

Build the project.

make build

Docker Image

Change ENV DOMAIN and ENV SECURE variables in Dockerfile to fit your needs, then build Docker image.

make docker_image

Run container from localtunnel image.

docker run -dit --restart always --net host --name localtunnel localtunnel

Usage Example

Start the server hosted on domain example.com.

./lt-server -d example.com

Create the tunnel to localhost:8000.

./lt-client -h http://example.com -p 8000

You should get generated URL, something like http://7e400f6d.example.com.

Open your browser on http://7e400f6d.example.com to check if its working then share the URL with your friends.

Use Locally (development)

For usage on local machine you first need to setup wildcard DNS for localhost development.

Installation guide for MacOS.

brew install dnsmasq

At the bottom of /usr/local/etc/dnsmasq.conf add

address=/localnet/127.0.0.1

Start dnsmasq.

sudo brew services start dnsmasq

For MacOS to resolve requests from *.localnet to localhost we need to add a resolver.

sudo mkdir /etc/resolver
sudo touch /etc/resolver/localnet

Add following line to /etc/resolver/localnet

nameserver 127.0.0.1

Reboot the machine to enable the resolver.

Start the your server using -d localnet flag

go run cmd/server/lt-server.go -d localnet -p 80

Start some web service, for example on port 6510, then connect with the lt-client.

go run cmd/client/lt-client -h http://localhost -p 6510

and you should get something like

your url is: http://33412dea.localnet

Open the URL in the browser and it should work.

Licence

MIT