One Article Review
| Source |  Errata Security |
|---|---|
| Identifiant | 7844 |
| Date de publication | 2016-05-31 19:27:00 (vue: 2016-05-31 19:27:00) |
| Titre | From scratch: why these mass scans are important |
| Texte | The way the Internet works is that "packets" are sent to an "address". It's the same principle how we send envelopes through the mail. Just put an address on it, hand it to the nearest "router", and the packet will get forwarded hop-to-hop through the Internet in the direction of the destination.What you see as the address at the top of your web browser, like "www.google.com" or "facebook.com" is not the actual address. Instead, the real address is a number. In much the same way a phonebook (or contact list) translates a person's name to their phone number, there is a similar system that translates Internet names to Internet addresses.There are only 4 billion Internet addresses. It's a number between between 0 and 4,294,967,296. In binary, it's 32-bits in size, which comes out to that roughly 4 billion combinations.For no good reason, early Internet pioneers split up that 32-bit number into four 8-bit numbers, which each has 256 combinations (256 × 256 × 256 × 256 = 4294967296). Thus, why write Internet address like "192.168.38.28" or "10.0.0.1". Yes, as you astutely point out, there are many more than 4 billion devices on the Internet (the number is closer to around 10 billion). What happens is that we can use address sharing (also called "network address translation"), so that many devices can share a single Internet adress. All the devices in your home (laptop, iPad, Nest thermistat, WiFi enabled Barbie, etc.) has a unique address that only works in the home. When the packets go through your home router to the Internet, they get changed so that they all come from the same Internet address.This sharing only works when the device is what's called a "client", which consumes stuff on the Internet (like watching video, reading webpages), but which doesn't provide anything to the Internet. Your iPad reaches out to the Internet, but in general nothing on the Internet is trying to reach your iPad. Sure, I can make a Facetime video call to your iPad, but that's because both of us are clients of Apple's corporate computers.The opposite of a client is a "server". These are the computers that provide things to the Internet. These are the things you are trying to reach. There are web server, email servers, chat servers, and so. When you hear about Apple or Facebook building a huge "data center" somewhere, it's just a big building full of servers.A single computer can provide many services. They are distinguished by a number between 0 and 65,535 (a 16-bit number). Different services tend to run on "well known" ports. The well known port for encrypted web servers is 443 (no, there's no good reason that number out of 65535 combinations was chosen, it's not otherwise meaningful). Non-encrypted web-servers are at port 80, by the way, but all servers by now should be encrypted.Web links like "https://www.google.com:443" must contain the port number. However, if you are using the default, then you can omit it, so "https://www.google.com" is just fine. However, any other port must be specified, such as "https://www.robertgraham.com:3774/some/secret.pdf". When you visit such links within your browser, it'll translate the name into an Internet address, then send packets to the combination address:port.Normally, when you look for things on the web, you use a search engine like Google to find things. Google works by "spidering" the Internet, reading pages, then following links to other pages. After I post this blog post, Google is going to add "https://www.robertgraham.com:3774/some/secret.pdf" to it's index and try to read that webpage. It doesn't |
| Envoyé | Oui |
| Condensat | yes 000 121 125 168 192 209 256 256 × 294 296 300 4294967296 443 5000 535 5900 65535 65536 967 about above acknowledgements actual add address address:port addresses administrators adress advertising after ago all allows already also among and 4 annoys another any anything appears apple are aren around article astutely avoid barbie because belief belong below:what between big billion binary bit bits blast blog both break browser bug building but call called can case cases center change changed chat choose chosen client clients closer com com:3774/some/secret com:443 combination combinations come comes common complete computer computers conclusioni connect connection consider consists constantly consumes contact contain control corporate couple current dark data decided default demonstrated describe describes desktop desktops destination device devices did different direction distinguished does doesn doing don each early easily else email enabled encrypted engine enough entire entries envelopes especially etc even every everybody everything exist expansive expected exposed facebook facetime fact fallacy fallacy is fast fiber files fills find findable finding finds fine finishing first flood following follows forwarded found four from full fun general get gigabit going good google grab grinding hacker hackers hand happens has have hear heartbleed home hop host hour hours how however https://www huge idea implications important index information inscrutable installed instead internet ipad isn just know known korean laptop large last like likely link linked links list listen log look looking lots machine mad mail maintain make many mass masscan maximum mean meaningful means might million moment more much must name names nearest need nest network networks newer noise non normally not note nothing now number numbers obscure obscurity often old omit once one only opposite order other otherwise out output packet packets page pages password patterns pdf people per person phone phonebook picture pioneers plan plants play point policy popular port ports possible post power principle professional program provide put putting random random/standard rate reach reaches read reading reads real really reason reasons relates reply research responses richer right robertgraham roughly router run running runs same sample scan scanning scans scratch scratch: screen search searches second seconds security see seems send sending sent server servers service services set share sharing should shown signs similar simply since single size slower some somebody something somewhere sort sorts specified speed spidering split ssh standard start starting stopping stuff such suppose sure system take takes techies telstra tend test than that them then there therefore thermistat these thing things think those though thousand through thus time toilets top translate translates translation transmit tried try trying tweet two type unique until use useful uses using usually valid version versions video visit vnc vulnerable wanted wanting watching way web webpage webpages websites weeks well what when where which who why wifi will windows within without won words works would write www years you your |
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