Day 4 Topics

Day 4 Assignment

Today we will review several core security concepts used in modern networks and web applications. These topics are commonly used when deploying servers, protecting web traffic, and securing remote access.

1. Review of DNS

DNS (Domain Name System) is responsible for translating human-readable domain names into IP addresses that computers use to communicate.

Example:

www.example.com  →  93.184.216.34

Common DNS record types:

• A record – maps a hostname to an IPv4 address
• AAAA record – maps a hostname to an IPv6 address
• CNAME – alias to another hostname
• MX record – mail routing record
• TXT record – often used for verification or security policies

Example DNS lookup command:

dig google.com

or

nslookup google.com

Key security considerations:

• DNS spoofing
• DNS cache poisoning
• Use of DNSSEC
• Protecting internal DNS infrastructure

2. Review of SSL / TLS

SSL (Secure Sockets Layer), now commonly referred to as TLS (Transport Layer Security), is used to encrypt communication between a client and a server.

It is commonly used to secure websites using HTTPS.

Example:

http://example.com
https://example.com

When HTTPS is used, data transmitted between the browser and the server is encrypted.

SSL/TLS relies on certificates issued by trusted Certificate Authorities (CAs).

Example tools used to inspect certificates:

openssl s_client -connect example.com:443

Key concepts:

• Public key encryption
• Private key encryption
• Certificate authorities
• Certificate chains
• Expiration and renewal

3. Review of SSH Keys

SSH keys are used to authenticate users without requiring passwords. They are commonly used for secure remote access to Linux servers.

SSH uses a pair of keys:

• Public key
• Private key

The public key is stored on the server inside the authorized_keys file.

Example command to generate a key pair:

ssh-keygen

Example location of SSH keys:

~/.ssh/id_rsa
~/.ssh/id_rsa.pub

The public key is copied to the server:

~/.ssh/authorized_keys

Example connection using an SSH key:

ssh username@server-ip

Key security benefits:

• Stronger authentication than passwords
• Protection against brute force attacks
• Ability to disable password logins

4. Research on Security Products

In today's assignment you will research several types of security and networking products that are commonly used in home and small office networks.

Categories to research include:

• Antivirus / Endpoint Protection
• Home Firewalls
• Networking Equipment (routers and switches)
• Servers
• Wireless Access Points

For each category, identify at least two vendors and review their products.

Examples of vendors:

• Antivirus – Bitdefender, Microsoft Defender, CrowdStrike
• Firewalls – pfSense, Firewalla, Fortinet
• Networking – Cisco, Ubiquiti, TP-Link
• Servers – Dell, HP, Lenovo
• Access Points – Ubiquiti, Aruba, TP-Link Omada

You will also design a simple home network layout that includes:

• Internet connection
• Firewall or router
• Switch
• Wireless access point
• Client devices

Example network diagram:

Internet
   |
ISP Modem
   |
Firewall / Router
   |
Switch
 |   |   |
PC  NAS  Access Point
          |     |     |
       Laptop Phone Smart TV

The goal of this research is to understand how these products fit together to create a secure and functional network.

End of Day 4 Topics