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網路管理final

大厝歹拚掃

5G 核心網路設計與實作 + free5GC:第五代行動網路之核心網路開發及架構

  1. List 3 advance of 4G as compared with 3G.

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    • Packet-switched only core network
    • Simplified architecture/Flat architecture
    • Separation of control plane and user plane
  2. List 3 Key 5G Use Cases.

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    • eMBB(enhanced Mobile Broadband)
    • URLLC(Ultra Reliable Low Latency Communications)
    • mMTC(massive Machine Type Communications)
  3. Briefly describe the full name and list 3 functions of the following functions of 5G network functions. AMF, SMF, UPF, AUSF, PCF, NSSF.

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    • AMF: Access and Mobility management Function
    • SMF: Session Management Function
    • UPF: User Plane Function
    • AUSF:Authentication Server Function
    • PCF: Policy Control Function
    • NSSF: Network Slice Selection Function
  4. Draw the architecture of 5G Non-Standalone Type 3 and 3a.

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  5. Draw the 5G SBA architecture with UE, gNB, UPF, and AMF, SMF, UPF, AUSF, PCF, NSSF

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  6. What is the 5G e2e latency and air latency, respectively?

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    • E2E latency: end-to-end (端點到端點) 的延遲時間 < 5ms (2反過來5)
    • air latency: 資料在空氣中傳播造成的延遲 < 1 ms (a1r)
  7. What is SBA in 5G?

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    Elements are defined as network functions that offer their services via interfaces of a common framework.

  8. List two types of SBI in 5G and draw their architecture, respectively.

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    • Request - Response
    • Subscribe - Notify
    • architecture - 投影片(3/3)
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  9. List 2 popular open source 5G core network and 1 popular RAN emulator

    • open5gs、free5gc
    • ueransim

4-4-1 5G 安全挑戰與要求

  1. 5G security scope is partitioned into four different domains, what are them?

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    • User
    • Network
    • OAM&P
    • Security Management
  2. List the first 3 security domains in 5G.

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    • Network access security
    • Network domain security
    • User domain security
  3. What is bidding down attacks in 5G security.

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    • (讓你沒辦法存取5g)
    • An attacker could attempt a bidding down attack by making the UE and the network entities respecively believe that the other side does not support a secutiey feature, even when both sides in fact support that security feature
  4. What is the key length of 5GC and NG-RAN encryption and integrity protection algorithms?

    chatGPT
    ​​​​​​​ - The key length for encryption in 5GC and NG-RAN is typically **128 bits** for Advanced Encryption Standard (AES-128), and for integrity protection, algorithms like UIA2 and CIA2 use a key length of **128 bits**. Keep in mind that specifications may evolve, so it's advisable to refer to the latest 3GPP documentation for the most up-to-date information.
    
    • 128 bits
  5. List three significant improvements to combat false base stations in 5G system.
    <Study on 5G Security Enhancement against False Base Stations (FBS) (3GPP TR 33.809)>

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    • SUPI concealment
    • Guaranteed GUTI refreshment
    • Protected redirections
    • A general informative detection framework
    • 5G security inherited from earlier generations like mutual authentication between UE and network, integrity protected signalling, and secure algorithm negotiations.
  6. Two categories of attacks against 5G UEs over radio interfaces

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    • Active attacks
      an attacker actively injects signal or messages to influence what UE would receive
    • Passive attacks
      an attacker silently sniffs sigals exchanged between a UE and a gNB
  7. List 3 different active attacks in 5G.

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    • Radio Jamming
    • Signal Shadowing
    • Message attacks
  8. Passive attacks can be classified into 2 sniffing, What are them?

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    • Uplink sniffing
    • Downlink sniffing
  9. List the first 3 Key Issues of 5G Security?

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    • Security of unprotected unicast messages
    • Security protection of system information
    • Network detection of false base stations
  10. Please draw the architecture of FBS authentication relay attack in the same PLMN

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  11. List 3 messages between the UE and the network with a MitM FBS.

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    • The pre-authentication traffic
    • MAC/RLC layer message headers
    • Lower layer control messages such as buffer status reports
  12. How to support high handover robustness during Conditional Handover in order to avoid UE Connecting to False Base Station

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    • support conditional handover in addition
    • the source gNB A sends threshold to the UE to make the handover decision
    • additional signalling to report measured signalling is not needed so that HO rebustness can be guaranteed
  13. List 2 new 5G features related to service delivery for CIoT capable Ues.

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    • for the infrequent transmission of small data
    • for the frequent transmission of small data and is targeted at more active Ues

5G Security Overview

  1. List 3 Challenges of Cellular Network.

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    • Wireless medium: boardcast nature
    • Mobility: changes in network attachment points
    • Wireless device constraints
  2. For security in 5G, list 3 Device Threats.

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    • Bots
    • DDoS
    • MitM Attacks
    • Firmware Hacks
    • Device Tempering
    • Malware
    • Sensor Suceptibility
  3. For security in 5G, list 3 Air Interface Threats.

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    • Jamming
    • MitM Attacks
    • Eavesdropping
  4. For security in 5G, list 3 Core Network Threats.

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    • Software issues
    • API vulnerabilities
    • Networking Slicing issues
    • DoS and DDoS attacks
    • Improper Access Control
    • Virtualization issues
  5. List the first 3 security domains in 5G.

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    • Network access security
    • Network domain security
    • User domain security
  6. Draw the architecture and describe the mechanism using encryption algorithm with SUPI and SUCI for Trust Model: Roaming Scenario in 5G security.

    • (SUPI + public key -> SUCI; SUCI + private key -> SUPI)
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  7. What is bidding down attacks in 5G security.

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    • making UE and network entities believe that the other side does not support a security feature
  8. What is the key length Requirement on 5GC and NG-RAN related to AS and NAS protection.

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    • 128 bits
  9. What is the key length Requirement on 5GC and NG-RAN related to Network interfaces.

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    • 256 bits

5G Authentication

  1. What is the General solution for Remote Authentication in 5G?

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    • General solution: challenge-response protocols
  2. What are 2 goals of 5G Authentication?

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    • Mutual authentication between UE and network
    • Providing keying material for subsequent security procedures
  3. What are 2 Main functions of AKA?

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    • Mutual authentication
    • Derive cryptographic keying materials
  4. Describe the architecture for Initial Attach and Re-attach of 4G EPS-AKA, including two IDs in identifying UEs in LTE networks.

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  5. What are Weaknesses in 4G EPS-AKA?

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    • UE IDs are sent over the air without encryption
    • Authentication is made solely by the serving network
  6. What is 5G Permanent Identifier? What is 5G Permanent Identifier with Privacy? What are the difference between them?

      1. SUPI
      1. SUCI
      • A privacy preserving ID containing the concealed SUPI
      • Only the MSIN part of the SUPI gets concealed
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  7. List 3 Differences between 5G-AKA and 4G EPS-AKA?

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    • Entities involved in the authentication are different
    • UE always uses the public key of the 5G home network to encrypt the UE permanent identity
    • the 5G home network makes the final decision on UE authentication