File Sharing Over The Internet

Posted on: December 4th, 2009

You might have run into a situation where you were on the road and would have needed to access a file that was on your home, or office machine. There are some very complicated and involved solutions to this problem but there are simple ones. I like simplicity so I’ll show you one that I just found recently – it’s called Leaf Networks.

The way I found Leaf Networks was by looking for an alternative to Hamachi. Hamachi is a similar product that lets you create connections between any two, or more computer on the internet so that they can exchange data directly with each other. I actually used Hamachi for years. But when they got successful, they decided that it’s time to change. They came out a new version that just didn’t work, especially with the non-Windows based client (which they neglected to update). One of my customers have relied on the long distance file sharing, having her assistant actually in another state. So I had to find a solution. I’ve looked and looked – the discussion boards all over the internet were full with complaints about Hamachi’s (more specifically LogMeIn’s) changes. After a long search I stumbled upon Leaf Networks: http://www.leafnetworks.net/

I tried the software on a couple of computers and it was simple enough and I didn’t have any trouble with file sharing. Connections happened each time I had internet connection. So I made the switch from Hamachi to Leaf Networks. It actually has better control on who accesses what within the Leaf Network.

How does these software work?

In short they create a direct, secure channel between two computers over an internet connection.

It’s not as easy as it seems because the internet is full of firewalls. These firewalls block all traffic that is coming in but which is not a response to request sent out earlier. So sending out is not blocked but incoming traffic to any computer behind a firewall is heavily filtered. That’s a good thing as it keeps hackers at bay – but in the same time it makes any legitimate access to a computer from outside very difficult as well. The solution to this is called VPN, which stands for Virtual Private Network. A VPN creates a network that behaves as if computers were in a local network, with very little blockage of traffic between them.

Most VPN setups require high level of technical knowledge to configure routers and firewalls, as well as software. These need to be configured to let through a certain type of traffic (the VPN channel).

Leaf Networks (and Hamachi also) is a zero configuration VPN. Which means you won’t need to mess with network settings, it configures itself to create the necessary channels without changing anything in the network.

How can they do that?

The trick lies in the help of a third party – a mediation server. That’s the modern version of a matchmaker ) Let me explain this with the matchmaker analogy:

A matchmaker is a person, or group that can be easily approached by anyone. People tell the matchmaker what they are looking for, the matchmaker finds the other person/persons and makes the connection. Once the connection is established the matched up couple will deal with each other directly, the matchmaker is not involved anymore.

In essence that’s how the mediation server works too. It’s open to all connection requests. Because outgoing communication from a computer is rarely blocked by a firewall, the computers don’t have trouble initiating a connecting to the mediation server. Whenever a connection is established with a server outside of the firewall (it’s a router in most cases) it creates a channel between that server and your machine and the firewall allows a back-and-forth traffic on that channel. As soon as two machines that are connected to the mediation server and they are verified to be part of the same virtual network then the mediation server steps out of the picture and lets the two computers communicate directly with each other. Here’s a diagram of how this works (click for full size image.)

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