Network Security

Concept: Both DoS and DDoS attacks aim to make a website, server, or network unavailable by overwhelming it with excessive traffic or requests. The main difference lies in the number of sources and the scale of the attack. Step 1: {\color{red}Denial of Service (DoS) Attack}
A DoS attack:

• Originates from a single machine or IP address
• Floods the target with traffic or requests
• Exhausts system resources (CPU, memory, bandwidth)

It is relatively easier to detect and block since the source is limited.
Step 2: {\color{red}Distributed Denial of Service (DDoS) Attack}
A DDoS attack:

• Comes from multiple compromised systems
• Often uses a botnet (network of infected devices)
• Generates massive, distributed traffic

This makes it highly difficult to mitigate or trace.
Step 3: {\color{red}Key Differences}

• Source: DoS = single source, DDoS = multiple distributed sources
• Scale: DDoS is larger and more destructive
• Detection: DoS is easier to block; DDoS requires advanced mitigation tools

Step 4: {\color{red}Impact}
Both attacks can:

• Disrupt online services
• Cause financial loss
• Damage reputation

However, DDoS attacks are generally more severe due to their distributed nature.

Concept: A firewall is a network security device or software that acts as a protective boundary between a trusted private network and untrusted external networks such as the internet. It enforces security policies by filtering traffic and blocking malicious or unauthorized access. Step 1: {\color{red}Traffic Monitoring and Filtering}
A firewall continuously monitors data packets entering and leaving the network. It:

• Examines packet headers and contents
• Applies predefined security rules

Only trusted traffic is allowed, while suspicious traffic is blocked.
Step 2: {\color{red}Preventing Unauthorized Access}
Firewalls restrict access by:

• Blocking unknown IP addresses
• Restricting specific ports or services
• Allowing access only to authorized users or devices

This prevents hackers from directly entering the private network.
Step 3: {\color{red}Protection Against Cyber Threats}
Firewalls help defend against:

• Malware and intrusion attempts
• Port scanning attacks
• Unauthorized remote connections

Step 4: {\color{red}Traffic Control and Policy Enforcement}
Organizations use firewalls to enforce security policies such as:

• Blocking access to unsafe websites
• Limiting employee internet usage
• Logging network activity

Step 5: {\color{red}Types of Firewalls}
Common firewall types include:

• Network firewalls (hardware-based)
• Host-based firewalls (software on individual systems)
• Next-generation firewalls (NGFW) with deep packet inspection