Cyber Security: An Offensive Mindset - Networking

Link to full Summer Studio 2019

Introduction

A problem statement from the beginnning of the Cyber Security Studio were ‘How can I a benefit from completing a Cyber Security Credit?’, ‘Can I use what I learnt from this subject to be prepare for future interviews in the Cyber Security World?’ and ‘Where do I see myself in Cyber Security in next 5-10 years?’. These answer to questions are currently what I do not have and trying to solve by the end of the studio.

However, I am slowly solving one of my problem statement by applying for an interview at UTS under the role of Security Analyst Intern and was offered an interview on 22nd of February.

Prior to the interview, I had a help from a friend who knew someone who had previously had the interview in the previous years and was successful. Having no prior industrial experiences with IT and networks, they provided hints and tips of certain topics I should learn. I would need to learn basic networking theory, subnetting and OSI model.

This is going to be artefacts page of evidence I what I have found from researching and watching videos.

Lynda.com - Learning Subnetting

  • Understanding binary basics
    • Base 2
  • Converting between number formats
    • Binary to hexidecimal
  • Default gateway
    • Subnet mask value -> 255.255.255.0
  • What is a subnet mask?
    • Concept to reveal information
    • Cider notation. Classless Inter-Domain Routing (CIDR)
    • First 2 octets are network bits.
    • Second 2 octets are hot bits
    • Default subnet mask -> 255.0.0.0
  • Introduction to IPv4 addresses

Nuggets

  • Three different classes
    • A 1-127 (255.0.0.0)
      • 10.0.0.0/8
    • B 128-191 (255.255.0.0)
      • 65,536 addresses
      • 172.16.0.0 - 172.31.255.255.16
    • C 192-223 (255.255.255.0)
      • Popular submask to use
      • 256 addresses
      • 192.168.0.0
  • Operates at Layer 3 of the OSI model
  • Works closely with Layer 2 Address (Hop-by-hop)
  • Subnetting is changing the submask
  • 1 equals network
  • 0 equals host

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OSI Model

Please Do Not Touch Steve’s Pet Alligator

Physical Data-link Network Transport Session Presentation Application


Interview

The responses I should have gave instead.

Difference between TCP/UDP

What infrustructure have you implemented at home?

What is the different between Layer 2 and 3?

Layer 2 - Data Link * Frame * Switches, Ethernet, Bridges * MAC Address

Layer 3 - Network * Packet * Routers, IP, ICMP

How many networks are in a /24?

I said 128. It’s not. It’s 1.

Enumerating from my mistake. 11111111.11111111.11111111.00000000

128 | 64 | 32 | 16 | 8 | 4 | 2 | 1

There are 8 bits of host. There are 24 bits of network.

The subnet mask should be: 255.255.255.0

Using the last bit of network which is an increment of 1.

1 host in 1 subnet 0.0.0.0/24 0.0.0.124 0.0.0.224

What can this be?

That means there are 1 network per subnetted network.

I said 128 because I got mistaken by how many hosts there are. One octet of bits = 128+64+32+16+8+4+2+1 = 255.

What is a firewall? Do you know what are the last rules in the table?


Expectation of the Interview


After thought


Bibliography

Lyda.com 2019, ‘Learning Subnetting’, Lynda.com, viewed 20 Februrary 2019, https://www.lynda.com/iP-tutorials/Understanding-binary-basics/184143

Nifty tech tag lists fromĀ Wouter Beeftink