Essential Network Security Concepts

Posted on May 15, 2025 in Contemporary Music Composition

Firewalls and Network Protection

Firewalls: Mechanisms designed for protection. Their purpose is to allow only authorized data transmission and reception. They isolate and control traffic between separate networks.

What Firewalls Do (and Cannot Do):

  • Control traffic flow based on rules.
  • Separate networks.

However, firewalls cannot protect against:

  • Connections that bypass the firewall.
  • Malicious internal users.
  • Completely new, unknown threats.
  • Network viruses (though they can block infected traffic).

Denial of Service (DoS): An attack not intended to invade a system, but to make it unavailable. Any host connected to the internet could be attacked. DoS attacks often involve sending a large number of apparently valid requests to overwhelm a server. Mechanisms used to enhance security may sometimes be exploited in DoS attacks.

DDoS: Distributed Denial of Service, where the attack originates from multiple sources.

Virtual Private Networks (VPNs)

VPNs allow corporate networks to use public infrastructure securely.

  • Provide transmission security.
  • Utilize data tunneling.
  • Offer cost reduction.

Elements of a VPN Connection:

  • Tunneling: How data travels over the connection. Encryption is used, and the packet is encapsulated inside another packet.
  • Tunnel Ends: Only valid participants can send and receive data.
  • Underlying Transport: Adds headers and uses the existing network infrastructure (e.g., TCP/IP).

Wireless Network Security

Wi-Fi is popular in homes and businesses, especially where cabling is difficult. Since data is transmitted through the air, security mechanisms are essential.

Forms of Communication: Infrastructure and Ad-Hoc.

Risks of Using Wireless Networks:

  • Radio signals are easy to intercept.
  • Many users operate home networks without additional security measures.

What to Watch For as a Wi-Fi Customer:

  • Be aware when connected to a public network.
  • Have a firewall configured.
  • Use updated antivirus software.
  • Apply software patches promptly.
  • Disable file sharing.
  • Disable ad-hoc mode.
  • Use WPA encryption (if setting up a network).
  • Use VPN or SSH for remote connections.
  • Avoid services that do not use a secure connection (e.g., HTTPS).
  • Enable the network adapter only when it is needed.

Care When Setting Up a Wi-Fi Network:

  • Configure the access point (AP) to cover only the necessary area (office or residence).
  • Change the default settings of the AP:
    • PASSWORD
    • SSID (Network Name)
    • Configure settings only via a wired connection if possible.
    • Use WPA encryption whenever possible.
    • Use the GREATEST POSSIBLE KEY SIZE.

Enabling Wireless Network Security:

  • Access the control panel of the router (usually via a web browser at addresses like 192.168.0.1, 192.168.1.1, or 192.168.0.24, depending on the model).
  • Find the Security Configuration section.
  • Enable and configure the encryption key size.
  • Enter the encryption key.

Communication Security

Email is a primary form of communication on the internet. Security must be considered for both the computational environment and the internet network itself.

Email Security

When an email is sent, it might feel like only the source and destination machines are involved. However, the message often passes through dozens of servers before reaching its destination. Therefore, never send passwords or sensitive information via email.

Common Security Threats

There are various ways to attack a computer with different goals, from corrupting files to stealing information.

Some Threats Include:

  • Viruses
  • Worms
  • Trojans

A threat often ignored is the user themselves, due to lack of knowledge, system complexity, or insufficient time to read security warnings.

Understanding DNS Spoofing

DNS Spoofing is an attack where a hacker compromises a Domain Name System (DNS) server.

How it Works:

  1. A hacker breaches the DNS server and changes the IP address associated with a legitimate website, pointing it to their own IP address.
  2. A client queries the compromised DNS server to find the IP address for the requested page.
  3. The DNS server returns the hacker’s IP address instead of the legitimate one.
  4. When the client attempts to access the requested page, they are directed to the hacker’s machine.
  5. The hacker can then direct the client to a fake site designed to look legitimate and capture sensitive information like passwords or credit card details.
  6. The hacker’s server may then retrieve the actual page content from the legitimate server.
  7. The hacker directs the legitimate response back to the client. The client often does not realize what has happened.

Securing DNS (DNSSEC)

When DNS was originally designed, the internet was primarily used by universities. Efforts to secure DNS began around 1994, leading to the development of Secure DNS (DNSSEC). Secure DNS uses asymmetric encryption keys and digital signatures to verify the origin and integrity of DNS data.

Mobile Code Security

Early internet consisted mainly of static pages. With the evolution of the internet, applications like Java and JavaScript running on the client-side introduced new security considerations for mobile code.