Archive for the ‘VPN’ Category

SSL VPN: Architechture of VPN

On my last 2 posts, I had explained the ‘SSL‘ and the ‘VPN‘. What are they, and what is our purpose of using them. Now, we’ll see VPN Architecture. With a simple diagram, I shall try to make you understand.

VPN architectureLet us take our previous example of John. Here, in the figure, the VPN device has 2 Ethernet ports: a Public Port & a Private Port. The Public Port is directly connected to the Internet via firewall and routers. The Private Port is connected to the 30 computers in the XYZ Pvt. Ltd. Now, as we can see, John wishes to connect to VPN; he, using the Internet, can connect to the VPN.

Now, one more thing, we can see, in the figure, over the ‘Internet‘, there is something called “SSL Tunnel Thru Internet“. Remember SSL? This is that tunnel. It is encrypted through several algorithms, which depends on the manufacturer of the device. Some manufacturers uses AES-128 some uses RC4 algorithm.

One more thing, the VPN device looks alike just a normal ’24-port switch‘. It contains more than 1 Ethernet port. It contains all normal hardware components of a CPU: like a Motherboard, a Processor, RAMs, a Hard Disk Drive etc. They also contain some Operating Systems. Generally Linux OS is provided with the devices. The reason is open source, free and its robustness. More over Linux is such a dynamic OS, that, the administrator can perform any type of job there.

So, in a nutshell, this was a brief architecture of VPN devices. If you guys face any problem, just post them in comments or contact us. We shall try to help you.

Thank you.


SSL VPN: Part 1

Hello Friends!
This time I am here with SSL VPN. That means, here I will share with you the basic concepts of “SSL VPN: What is it and What it does?”
First of all, we need to know, what is VPN?
VPN is Virtual Private Network.
Again what is “Private Network”, and how is it “Virtual”?
A “network” is defined as the interconnection between computer systems, terminals or data communication facilities.
For example, this Internet, via which, right now, you are reading this article, is a network.
Now, what is “Private Network”?
This word “private” means something that is not licensed to access all users but some authorized users. Now, this “something” may be anything: some documents or some services or some tools – any thing. Large corporate houses, uses their own private network.

Let us clear this with a small example. Consider a corporate house XYZ Pvt. Ltd. They have an IP, say, ‘’. Now, in their office, they have 30 computers. Now, they want to put them in a LAN (Local Area Network). So, what will they do? They will use some ‘class – C’ based address-based IP network ‘’ and at their gateway, using a NAT (Network Address Translation). So, they will have 30 computers with an arrangement like this:
Computer 1: IP =>
Computer 2: IP => …. Etc.
So, now, this network will be called a private network that belongs to XYZ Pvt. Ltd. And unless licensed, none from outside can access this network.

Now, we will look why “Virtual”?
As we all know, the word “virtual” refers to some “state” that is not real, but is possible.
So, Virtual Private Network is a kind of network, which seems to be private but virtually. Here, an authorized remote user can access some resources of the private corporate network on a service provider’s shared network infrastructure, as if he is present in the private network.

Let’s take our previous example of XYZ Pvt. Ltd. Now, think of the situation. An employee, John, of the XYZ Pvt. Ltd., is in a holiday. Suddenly, he receives a phone, that, from his computer, he has to find some important presentation and mail the same to his boss who is also in other country, far from office. Now? If, john wants to do so, he has to use a secured channel over internet, via which he can access his computer that is situated in his office. This “secured channel over internet” is generally called the VPN.