計算機網路
參考自李春良老師 計算機網路課程部分PPT擷取
網路參考源: 國立台灣大學 Lecture Slides
Introduction to Computer Networks
Spring 2022
資安相關名詞
- botnet
- virus
- worm
- DDos
- IP spooting
- spyware
- packet sniffing (筆記手誤)
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網路基本概念
- cookies
- IMAP v.s. POP3
- DNS(Domian name system)
- tracked, torrent
- DNS poisoning attack
- DNS provider
- web cache
- condition GET
- persistent HTTP
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DNS的問題: 前身
假設一個DNS包含所有映射的DNS,會有四項問題
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- Single point of failure
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- Traffic volume
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- Distant centralized database
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- Maintenance
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解決方法 ---> Hierarchical database(筆記手誤)
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相關名詞
- Authoritire DNS Server
- Local DNS server
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- recursive query
- iterative query
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TCP觀念
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- reliable
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- flow control
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- congestion control
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- In transport layer
SSL加密
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- provide TCP encrypted connection
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- In application layer
SMTP(Simple Mail Transfer protocol)
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- hand shaking
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- transfer msg
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- closure
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Transport & Network layer
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TCP
TCP segment structure
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TCP retransmission scenarios
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- Lost ACK
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- Premature timeout
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- Commulative ACK
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- Congestion Control
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- AIMD --> Slow start問題
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- Longest prefix matching(LPM)
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網路連結方式
- Switch
- Bus
- Crossbar
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HOL (Hand of the line blocking)問題與排排程機制
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- 解法
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- FIFO
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- Priority
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- RR
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- WFQ(Weighted Fair Queing)
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ICMP protocol
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IP Addressing 方法
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* Subnet Group
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NAT(Networling Addressing Translation)
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Routing ALGO分類
- 根據router知道全域 & 區域資料
- Global: Link State ALGO
- Broadcast產生Forwading Table
- Dijkastra's algo
- 缺點(特色): 容易震盪(Oscillation Possible)
- Decentralized: Distance vector algo
- 鄰近節點找最短路徑
- Bellman Ford algo
- 缺點(特色): Bad news travels slow(count to infinity問題)
- 根據更新速度
- Static
- Dynamic
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Internet approach
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- Intra AS (AS 內部)
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- RIP(Routing Information Protocol)
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- OSPF(Open Shortest Path First)
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- IGRP(Interier Gateway Routing Protocol)
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- Inter AS (AS 間): 只有 BGP(Border Gateway Protocol)
- eBGP(egress)
- iBGP(ingress)
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Link layer
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- Link layer serice
- flow control
- error detection
- error correction
- half-duplex, full-duplex
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- Error Detection
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- Parity checking(Odd/Even)
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- CRC(Cyclic Redundancy Check)
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Multuple Access & MAC
Multiple Access |
Protocol 理想四要件判斷 |
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- MAC Protocol分類
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- Channel Partitioning(筆記手誤)
- TDMA(Time Division Multiple Access)
- FDMA(Frequency Division Multiple Access)
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- Random Access
- Slotted ALOHA
- Pure(unslotted) ALOHA
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CSMA(Carrier Sense Multiple Access)
- CSMA/CD
- CSMA/CA
- Taking turns
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ARP
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Ethernet
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