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Questions and Answers
What is the primary purpose of network security?
What is the primary purpose of network security?
Which of the following is NOT a reason for implementing network security?
Which of the following is NOT a reason for implementing network security?
What does a firewall do in network security?
What does a firewall do in network security?
Which component is commonly used in combination with firewalls for enhanced security?
Which component is commonly used in combination with firewalls for enhanced security?
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What type of firewall filters packets based on rules?
What type of firewall filters packets based on rules?
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What is the role of a De-Militarized Zone (DMZ) in a network?
What is the role of a De-Militarized Zone (DMZ) in a network?
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What vulnerability is commonly associated with social engineering attacks?
What vulnerability is commonly associated with social engineering attacks?
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Which statement best describes packet sniffing?
Which statement best describes packet sniffing?
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What is the main purpose of well-known port numbers?
What is the main purpose of well-known port numbers?
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Which of the following port numbers is used for Secure Shell (SSH)?
Which of the following port numbers is used for Secure Shell (SSH)?
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What type of attack aims to make a network service unusable?
What type of attack aims to make a network service unusable?
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Which protocol suite is used to secure Internet Protocol communications?
Which protocol suite is used to secure Internet Protocol communications?
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What is a common solution for defending against packet sniffing?
What is a common solution for defending against packet sniffing?
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What method is often employed in a dictionary attack?
What method is often employed in a dictionary attack?
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Which of the following is NOT a TCP port used for a specific application?
Which of the following is NOT a TCP port used for a specific application?
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What behavior characterizes social engineering attacks?
What behavior characterizes social engineering attacks?
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Study Notes
International & Access Foundation Programmes - Computer Science Module, Semester II, Part 5: Networks: Network Security
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Overview of Network Security:
- What is network security?
- Why is network security needed?
- Who is vulnerable to network attacks?
- Common security attacks and countermeasures:
- Firewalls & Intrusion Detection Systems
- Denial of Service Attacks
- TCP Attacks (Spoofing)
- Packet Sniffing
- Social Engineering
Why Network Security is Needed
- Protecting Vital Information: Protects sensitive data like trade secrets, medical records, and personal information while allowing authorized access for those who need it.
- Authentication and Access Control: Provides methods to confirm the identity of users and control access to resources
- Logins, Passwords, Biometrics:
- Resource Availability: Ensures 99.995% reliability of resources
Firewalls
- Basic Problem: Network applications and protocols often have security vulnerabilities
- Difficulty: Keeping up with changes makes securing hosts challenging
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Solution:
- Firewall administrators restrict access to end hosts
- Firewalls are regularly updated
- Firewall Analogy: A firewall is like a castle with a drawbridge – only one access point
- Hardware/Software: Firewalls can be hardware or software
- Routers: Some routers have built-in firewall functionality
- Software Firewalls: Unix, Windows XP/7/8, and Mac OS X have built-in software firewalls
- DMZ (De-militarized Zone): A security buffer between the internet and internal network. Separates web servers, email servers, and web proxies.
- Filtering Packets: Firewalls are used to filter packets based on defined rules. Packet filtering firewalls operate by examining packets and applying these rules.
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Windows 7 Default Firewall Configuration:
- 135/tcp open loc-srv
- 139/tcp open netbios-ssn
- 445/tcp open microsoft-ds
- 1025/tcp open NFS-or-IIS
- 3389/tcp open ms-term-serv
- 5000/tcp open UPnP
Ports
- Definition: Ports are endpoints of communication within an operating system.
- Well-known Ports: 1024 port numbers identify specific services on a host (e.g., http://www.example.com:8080).
- Port Association: A port is always associated with an IP address of a host.
Typical TCP Ports
- 21: File Transfer Protocol (FTP)
- 22: Secure Shell (SSH)
- 23: Telnet (remote login)
- 25: Simple Mail Transfer Protocol (SMTP)
- 53: Domain Name System (DNS)
- 80: Hypertext Transfer Protocol (HTTP)
- 110: Post Office Protocol version 3 (POP3)
- 119: Network News Transfer Protocol (NNTP)
- 123: Network Time Protocol (NTP)
- 143: Internet Message Access Protocol (IMAP)
- 161: Simple Network Management Protocol (SNMP)
- 194: Internet Relay Chat (IRC)
- 443: HTTP Secure (HTTPS)
Types of Attacks
- Intrusion Detection: Monitors a network for suspicious activity based on known patterns.
- Dictionary Attack (Brute Force): Tries various passwords from a dictionary or database.
- Denial of Service (DoS): Overloads a network service, making it unusable.
- TCP Attacks: Manipulates TCP packets to cause harm. An attacker can inject malicious data into the TCP stream, making recipients believe it came from a legitimate source.
- Packet Sniffing: A host intercepts and examines data on a network or broadcast medium.
- Social Engineering: Manipulating or tricking people into divulging sensitive information.
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Description
Explore the essential elements of network security in this module from the International & Access Foundation Programmes. Understand the reasons network security is crucial, learn about common security attacks and countermeasures such as firewalls, and gain insights into authentication methods. This quiz will test your knowledge on securing networks against various threats.