Explain like I'm five · Security

What is a DDoS?

Distributed Denial of Service, told as a story about a fake crowd swarming the castle gate.

COUNTERa hundred a dayas long as only that many come, all is well

The counter can serve about a hundred people a day.As long as only that many come, all is well.

COUNTERa real customerthey buy nothing; they just stand in line

The thief sends ten thousand fake customers at once.The fakes buy nothing — they just stand in line. Real customers can't get in.

COUNTERone whistleinfected things all over townthe thief steals nothing — he makes the counter useless

A DDoS jams the counter with a fake crowd.The thief steals nothing; he makes the counter useless. The fakes are infected things (zombies) all over town.

The zombie hordeinfected fridges, cameras, routers
They buy nothingthey only fill the line
From all over townyou can't block just one house
Sheer sizetens of thousands a second
depots in every town take the crowdHuman? Raise your hand…robots can't raise a handand one turn per person

Spread them thin, and make them raise a hand.The depots in every town take the crowd. Robots can't raise a hand (the note checker). And one turn per person.

some robots can raise a handthey look exactly like real peopleSALE TODAY!a day the real crowd cameeasy to mistake for the fake crowd

Some fakes look exactly like real people.Some robots can raise a hand. And a real rush (a sale) looks just like an attack. You never fully block it — you ride it out.

In one breath

A DDoS = a fake crowd of infected things (zombies) from all over town, jamming the counter so real customers can't get in. It steals nothing — it makes things unusable.

Distributed Denial of Service. The Mirai botnet (2016) made it famous with hundreds of thousands of cameras and routers. Defenses: depots (CDN), the laundry (scrubbing), raise-your-hand (challenges), one turn each (rate limits). Cloudflare, Akamai, AWS Shield.

When grown-ups say it

Botnet
The zombie horde. Infected things under the thief's control. Their owners have no idea.
Bot · zombie
The infected fridge. Knocks on the counter when told. → the things that can't wear a tag are the usual victims
Command & control
The thief's whistle. Moves ten thousand at once. → the burglar's habit
Volumetric · L7
Flooding the yard · knocking on the counter. Either fill every road, or hit one counter with hard notes only.
Rate limiting
One turn per person. The same face a hundred times a second gets paused.
Challenge
Raise your hand. Ask for something robots can't do. → the note checker
Scrubbing center
The laundry. Route the crowd to a huge yard, filter the fakes, pass only real ones on.
Flash crowd
A real rush. The sale-day crowd. Not an attack, but it looks like one.
Next story
The Thief's Lock on Every Chest →
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