【Fun fact】An attack launched by a network cable is a must-have for breaking the roommate network!

Not long after I went to college, I encountered a headache. The rich second generation brought laptops with them when they first arrived, which made us envious and jealous of the dicks who could only play with their mobile phones. triggered by a network cableattack

Not long after I went to college, I encountered a headache.

The rich second generation brought laptops when they first arrived, which made our dicks who could only play with mobile phones envious and jealous. The terrible thing came, the power was cut off at night, so the laptop could still play after the lights were turned off.

Unfortunately, we also have one in our dormitory. Often after the lights are turned off, you have to use the battery clean. While playing the game, the voice is also playing, and the music is playing, which is very tormented. Although it has been persuaded to change, it will be restored in a few days.

In order to urgently change this situation, but I didn't want to get involved with new classmates, I decided to use technical solutions to solve it.

But at that time, there was only a Nokia slider mobile phone, and everything was empty talk without equipment. The only thing that works is to secretly set a scheduled task in his computer and automatically shut down at night. But if you find it, it's even worse, and there is no technical content at all.

Helplessly, I can only turn my attention away from the computer and on the Internet. If you can't access the Internet, even if you can use the computer, you won't stay up late to play stand-alone games.

Since his network cable socket can be used when he first came, I must have a signal here. The previous session must have been passed, and it will not be sealed after leaving. Taking advantage of the fact that there was no one in the dormitory one day, I dragged the network cable of the notebook to my side and tried it, and sure enough, there was a signal! Suddenly I came to my senses and felt hopeful!

Maybe you will say, it is impossible to connect the network cable to Nokia, and then use some spoof software~ Of course not, how could mobile phones be so advanced at that time.

In fact, we don't use any soft! Piece! , you don't even need to be hard! Piece! —— In addition to a network cable.

If you want to talk about how to play with the network cable, you can also start from the day you installed the set-top box before.

For a while, digital TV became popular in many cities. We are no exception, door-to-door free set-top boxes, and free door-to-door installation. Huashu TV is originally the same as Netcom, and digital TV is of course the broadband of shared Netcom.

Since Netcom has been opened before, this time I have to connect the set-top box to the Internet, I think I have to send at least a switch. However, as soon as the installation master came in, he neither took out the switch nor even the hub, but cut the network cable with scissors!

At that time, I was stunned, what kind of ghost is this? Although I was quite excited about network link protocols at that time, I didn't know anything about the physical layer. The master said calmly that only four network cables are enough, and some are spares. So from the previous line, four were removed for the set-top box.

This was beyond my expectations, and the set-top box was connected without any equipment! So, it started to be whimsical again...

Are these two separate shares two independent users in terms of the switch? If they are connected together, is the effect the same as inserting two threads? Can it be the same as short-circuiting the LAN?

Take the test with excitement, and sure enough! It really hangs up the network of the entire community!

For a long time after recovery, I couldn't dial the number. In the sniffer, I found that many neighbors were constantly dialing. Obviously, the two 4-strand cables were just connected and the external STP packet was also forwarded, causing the cell network to be isolated externally.

On this day, I changed my previous opinion. It turns out that with just one network cable, you can have a VLAN storm!

Why does a network cable plug into two ports of a switch cause a storm? Because the switch forwards packets sent to the broadcast address to all interfaces. If there are two interface loops, once the broadcast packet appears, it will be sent in a loop to each other, depleting the bandwidth of the entire device. Don't underestimate the switch, it is naturally designed for packing, and the storm can fill every interface and play the traffic of the backplane bandwidth. The STP protocol is designed to solve this problem by performing loop detection.

Despite learning about this new skill, the knowledge of physics was basically useless, and I forgot about it - until the day I found a signal under the bedroom seat.

According to the memories, there were also LAN games played between the dormitories, and it was obvious that this was not an independent network segment, so I was even more confident!

Immediately find a mesh cable, remove the crystal head on one side, scrape off the skin, and then glue the corresponding four strands in pairs. Sure enough, the nearby dormitory began to come - no, first there was silence for a few seconds, then screams and roars. "Stuck!" "Who dropped?" ", what's the situation?" , "Damn, the network is broken~~~". . .

When I ran out of the corridor, the whole building was in a riot! It turns out that this dormitory building has no VLAN at all, and all the hundreds of dormitories are connected together!!

At this time, I was both excited and worried. Excitedly, in the future, with a computer, we can catch the traffic of thousands of people. What worries me is that now I just want to spoof my dormitory and don't want to involve everyone.

Anyway, the action continues. It was supposed to rest after the lights were turned off, and it wouldn't be bad if everything was broken.

At this time, there was no major technical problem, and it was almost implemented. How to operate calmly and covertly?

In order not to expose the absurdity of not having a computer and plugging in a network cable, I tried to route the wires along the shielded cabinets, from the back of the wardrobe to the bed. The remaining horizontal part is buried in the crevices next to the bed and covered with a mat.

If you don't look closely at the whole layout, you won't be able to find it at all~

After the lights went out that night, the night owls started to move again, and I couldn't wait to start experimenting. Like several other students, he pretended to be playing with his mobile phone, but in fact he had begun to wire quietly, which felt like an underground intelligence officer.

When the last strand is caught, the smooth game sound immediately stutters. After all, the entire building is in this LAN, and the number of broadcast packages is quite large.

I can only hear the background music of the game, but there are no sound effects!

Thinking of 100Mbps of traffic passing through the network cable in my hand, it was as if I saw dense ARP, NetBIOS broadcasts flashing in the darkness - and the pitiful, squeezed game packets.

The afternoon commotion broke out again. Although it is much less after the lights are turned off, it is obviously clearer in the night environment.

Most of the disconnected people were unwilling and wanted to continue playing. This time, I don't plan to be so violent, in case the circuit detection is triggered, maybe the whole building will be blocked.

So, change it to a few seconds and disconnect. Put it on and disconnect again... Although the game works, it is constantly stuck in stuttering. Not long after, there were warm shutdown sounds, and they all fell asleep.

The first battle was won! Finally got a good night's sleep.

In the first few days, the effect was very ideal, and everyone went to bed obediently early.

But it didn't take long for them to find out that the network would be restored after a while. The reason is simple, my brother let go of the thread before he fell asleep, so they started going crazy again.

In a daze, it will be much more difficult to put the network cable back on. Often entangle irrelevant things together, and the result is ineffective.

Therefore, a user experience improvement is needed.

In fact, three of the strands are glued in advance, and only one strand is actually controlled. It is better to hide all three shares in advance and leave only one by your side, so that you will not make a mistake.

I changed the network cable and remade it. This time, 3 of them were directly taped and hidden behind the closet, leaving only one to drag up. The line is also much thinner.

In this way, it is the same as a circuit switch. There are only two threads in total, just put them on or apart.

Even in sleep, you can easily control the network of the entire building with just a few fingers!

However, with such a rudimentary device, there will always be operational errors.

In the middle of the night on a weekend, after being woken up by the all-night, I put on the network cable and continued to sleep. I didn't expect to be too sleepy this time, so I fell asleep directly. It wasn't until around 10 a.m. that I was woken up by a knock on the door.

I thought it was the classmate next door, but I kept knocking on the door, and when I opened it, I found an uncle with a toolkit coming in. At this time, I suddenly realized that the network cable I was connecting forgot to disconnect!! After a whole night, they all came to the door!

At this time, it was too late to clean up, thinking that this time it was finally going to be exposed. But the master swept it away and found that our table was clean and there was nothing. Only the notebook was open, and it hadn't been turned off. So he stepped forward and unplugged the network cable, and left.

Luckily escaped this catastrophe and urgently needed to improve.

It would be ideal if it could be turned on before going to bed and automatically turned off after falling asleep. No more disconnection in your sleep.

So I planned to make a flexible switch that must be pressed to turn on and close when released. In this way, after falling asleep, the body relaxes and automatically disconnects.

After some improvements, the switch was made extremely hidden: two threads were stuffed into a sock, and cotton and other elastic things were stuffed inside. Under normal circumstances, the lines are separated, but if you press down slightly, it will catch up, and it will return to normal after release.

But it was strange to pinch the socks in his hand, so he hid them behind his feet. At this point, whenever the night is noisy, as long as you tiptoe a little, the surrounding atmosphere immediately becomes exceptionally quiet.

At this point, the equipment that cost a total of two yuan to build can allow the toes to control the network status of thousands of people, which is simply a sense of accomplishment :)

Not long after,Everyone seems to have discovered a pattern, as long as the sound is too loud, the net will get stuck, but I couldn't find the reason. So they all became obedient and quietly surfed the Internet. (It's very funny every time I think about it)

Of course, this device was only put into service for half a year. In the second semester, everyone installed their computers, so they had a good night surfing the Internet together.