1.6.8

Firewalls

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Firewalls

It is important to monitor and filter data coming into and out of a network.

Firewalls

Firewalls

  • A firewall is either a hardware device or a piece of software which sits between a device and the Internet.
  • Firewalls inspect and filter incoming and outgoing data packets.
  • They try to stop hackers gaining access to the network and stop malware getting into the network.
Packet filtering

Packet filtering

  • One role of the firewall is packet filtering.
  • The firewall inspects each packet and drops those which do not meet certain criteria.
IP-address filtering

IP-address filtering

  • The firewall only allows traffic from certain known sources.
  • This can be used to prevent denial of service attacks.
Port-blocking

Port-blocking

  • Firewalls can block access to certain ports.
    • One important port is port 22, which allows remote access via the Internet. By blocking this port, we can prevent hackers trying to take over the server.
Jump to other topics
1

Computer Systems

1.1

Data Representation

1.1.1Binary Numbers1.1.2Negative Binary Numbers1.1.3Hexadecimal1.1.4Using Hexadecimal1.1.5Converting Binary & Hexadecimal1.1.6Converting Denary & Hexadecimal1.1.7Capacity1.1.8Calculating Capacity Requirements1.1.9Binary in Computer Systems1.1.10Data Compression1.1.11Run Length Encoding1.1.12File Formats
1.2

Data Transmission

1.2.1Packet Switching1.2.2Data Transmission1.2.3Universal Serial Bus (USB)1.2.4Parity Check1.2.5Checksum & Echo Checks1.2.6Encryption
1.3

Hardware

1.3.1Elements of Computer Systems1.3.2Types of Computer System1.3.3Von Neumann Architecture1.3.4The Fetch, Decode, Execute Cycle1.3.5Factors Affecting CPU Performance1.3.6Computational Logic1.3.7Input Devices1.3.82D & 3D Scanners1.3.9Code Readers1.3.10Solid State Storage1.3.11Magnetic Storage1.3.12Examples of Magnetic Storage1.3.13Optical Storage1.3.14Examples of Optical Storage1.3.15Types of Optical disk1.3.16Storage Requirements1.3.17Translation - Compilers1.3.18Translation - Interpreters1.3.19Translation - Assemblers1.3.20Acoustic Sensors1.3.21Flow Sensors1.3.22Gas Sensors1.3.23Humidity Sensors1.3.24Infrared Sensors1.3.25Level Sensors1.3.26Light Sensors1.3.27Magnetic Field Sensors1.3.28Moisture Sensors1.3.29pH Sensors1.3.30Pressure Sensors1.3.31Proximity Sensors1.3.32Temperature Sensors1.3.33Network Hardware
1.4

Software

1.4.1Operating Systems1.4.2Interrupts1.4.3High-Level Languages1.4.4Low-Level Languages
1.5

The Internet & its Uses

1.5.1The Internet1.5.2Uniform Resource Locators (URLs)1.5.3DNS1.5.4HTML1.5.5Cookies1.5.6Web Hosting1.5.7Digital Currency
1.6

Cyber Security

1.6.1Forms of Attack1.6.2Penetration Testing1.6.3Types of Malware1.6.4How Malware Spreads1.6.5Protecting Against Malware1.6.6Information Security1.6.7Structured Query Language (SQL) Injection1.6.8Firewalls1.6.9Authentication: User Access Levels1.6.10Authentication: Passwords1.6.11Social Engineering1.6.12Phishing1.6.13Denial of Service Attacks
1.7

Automated & Emerging Technologies

1.7.1Automated Systems1.7.2Robotics1.7.3Artificial Intelligence
2

Algorithms, Programming & Logic

2.1

Algorithm Design & Problem Solving

2.1.1Computational Thinking - Abstraction2.1.2Computational Thinking - Decomposition2.1.3Computational Thinking - Algorithmic Thinking2.1.4Pseudocode2.1.5Flow Diagrams2.1.6Interpreting, Correcting & Completing Algorithm2.1.7Correcting Algorithms2.1.8Completing Algorithms2.1.9Testing2.1.10Types of Testing2.1.11Test Plans2.1.12Validation & Sanitation2.1.13Authentication & Contingencies
2.2

Programming

2.2.1Programming Fundamentals - Variables & Constants2.2.2Programming Fundamentals - Comments2.2.3Programming Fundamentals - Input & Output2.2.4Data Types2.2.5Casting2.2.6Controlling Program Flow - Sequence2.2.7Controlling Program Flow - Selection2.2.8Controlling Program Flow - Iteration2.2.9Modularity - Subroutines2.2.10Modularity - Scope2.2.11Arrays
2.3

Databases

2.3.1Structuring Data - Records2.3.2Structuring Data - Databases2.3.3SQL
2.4

Boolean Logic

2.4.1Binary Systems2.4.2Logic Circuits2.4.3Truth Tables2.4.4Evaluating Expressions2.4.5Boolean Operators2.4.6End of Topic Test - Logic

Practice questions on Firewalls

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  1. 1
    Why is port 22 often blocked by the firewall?Multiple choice
  2. 2
    Which of these are services offered by firewalls?True / false
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Structured Query Language (SQL) Injection

Authentication: User Access Levels