TIL 20191208

jakeshin·2019년 12월 8일
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TIL

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1. network protocol: encapsulation

link layer switchrouter
packet switchpacket switch
1~2 layer1~3 layer

capsule을 씌워가며 메시지를 전송하면, ene-system(or packet switches)는 씌워진 캡슐을 벗겨 메시지를 해석하고, 필요하면 다시 자신의 캡슐을 씌워 전송한다.

2. DoS(denial or service) Attack

  • vulnerability attack: host가 작동시키게 해서 동작을 멈추게 하는 등 악성 행동을 수행시킴.
  • bandwidth flooding: flood fake packets, block normal packets
  • DDoS: 공격자가 많은 숙주들을 감염시켜 둔 후, 한 host로 한 순간에 packet을 숙주들이 공격하게 지시함.
  • connection flooding: flood fake TCP connection, block normal connection

3. packet sniffer(패킷 훔치기)

encryption으로 방지

4. IP spoofing(사칭하기)

end-point authentication이 필요!

5. History of computer networking

  1. circuit switching -> packet switching develop
    ARPAnet(individual closed network) start
  2. internetworking
    network of networks 개념 도입, TCP, UDP develop
    ALOHAnet develop: multiple access protocol
  3. network 확산
  4. internet bubble
    ARPAnet disappeared, WWW appear, web service flood
  5. millenium
    content provider: made datacenter -> bypass ISP

6. Application layer (new chapter!)

  • web app => server와 client 로 나뉨
    타 layer에 대한 제어 x
  • application architecture != network architecture
  • role of datacenter
    - bypass ISP
    • handle flooding requests
  • application architecture
    1. server-client
    - server
    - always awake
    - has static address(IP)
    - client
    - init connection
    1. P2P architecture
      • few(or never) depend on server
        • host and host make peer
        • ex) file share, dowload accerlator, messangers
    2. hybrid
      • user server-client and p2p
        • ex) instant message application
  • Process
    - host communicate not by program, but by process.
    two host communicate by exchange message.
    In this work, the door is socket and the house is process.
    socket: API between application and network
    • when sending packet, recieving process should have own address, and the packet should have two information - IP address, and port number.
      1. IP address: address of receiving host
      2. port number: recieving process of host.
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