5 cents to build your own Throwing Star LAN Tap

5 cents to build your own Throwing Star LAN Tap

Cause:

The WEB "Wang" was boring to write PHP code at home on weekends. I was thinking about something interesting. I saw Throwing Star LAN Tap, but I didn't have time to play it, eager to open a treasure to get a back, a search will be dumb, a 1, 2 hundred dollars. When I buy a pair of trousers as silk, I think 100 yuan is a little too much. How can I spend money. It was quite easy to get one by yourself.

Analysis:

First, let's look at our analysis objects.

1. RJ45 interface network cable

The standard RJ45 interface has a total of 8 pins, each of which has different definitions. For details, refer to pin definitions in M. See:

The standard RJ45 interface is fixed, but there are two common Connection Methods: T568B and T568A.

The most common on the market is T568B, Which is T568B. No matter which connection method interface is a fixed lead, no matter which connection method is used in the following article.

Description of T568B interface (MB network condition ):

1. white orange: TX + (data transmission +) interface 2. orange: TX-(data sending-) Interface 3. white-Green: RX + (data receiving +) interface 4. blue: Disabled 5. white Blue: Disabled 6. green: RX-(data receiving-) interface 7. white BROWN: Disabled 8. brown: Disabled

From the description, we can see that the MB network used in daily life only uses four lines and two lines to send and receive messages.

2. How to capture data

So the question is, how can we capture data when we know the definition of the wiring? In fact, we can see from the title that the "TAP" is a common line attack. So how can we establish a line to get data normally? I drew a simple figure:

On the left is the description of T568B, which can be seen as a plane chart with the contact point facing up at the crystal head.

On the right is our key line chart:

A and B: end A and end B are connected directly to the two network cable interfaces.

C: The C client can see 1 and 2 lines (3, 6-> 1 and 2) on the and B communication lines) that is, the data receiving interface of the C end is connected to the data sending interface on the and B communication lines.

D: the root C side of the D side uses 3, 6 (1, 2-> 3, 6) of A and B communication) that is, the data sending end of the D end is wired to the data receiving end of the and B communication lines.

In fact, careful people have discovered that, why not build A line to A and B communication lines at the same time on A short-term end? So there is no interface left?

Here is an example that is easy to understand:

A and B shouted at each other. A asked B what's your password? B calls 123456. At this time, you can indeed hear his password: 123456, that is, the receiving end can hear it. But if B calls 111111 at the same time, you can also say A's password to, then A will hear the answer given by two people at this time. Who should I trust? This is where the communication network is disrupted.

Production process:

Here, I sold a one-to-two interface in the hardware department for convenience, with 5 cents. Physical objects:

Take a look at the internal structure as follows:

After separation with the tiger pliers, use several wires to weld the cables as shown in the figure below:

OK, don't ask why the web "Wang" has a duobang line. I won't tell you how to replace the gold coins you cheated in the last article ~.~ After the installation is connected to the online server, visit qq.com to capture the package and check whether the package is correct.

In fact, things are very simple. As a scientific article, you can spend a small amount of money on physical black ~.~