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Network+ Exam

Firewalls

October 29, 2025

  • #network+

Firewalls

Uses a set of rules defining the types of trafffic permitted on our networks.

Software/hardware

virtual/physical

hostbased/network-based

NAT

PAT

packet filtering fireall - permits or denies traffic based on packet header.

session based firewall will allow info if yo uclick the link.

combine ACL and permit and deny with a stateful capibilities.

Next Gen firewall NGWF conducts deep paceet inspection .

layers 5 6 and 7 to get indepth info. WAF

ACL access control list. a set of rules

switch - MAC address

router ip address

firewall - ip address .

UTM unified threat managemt - combines firewall router, IDS , andimalware and other features into a singl edevice.

🔥 Firewalls

Purpose

  • Control inbound/outbound traffic using a set of rules.
  • Provide network security, segmentation, and monitoring.

Types of Firewalls

  • Hardware vs. Software
    • Hardware: dedicated appliances.
    • Software: runs on servers/PCs.
  • Physical vs. Virtual
    • Physical: standalone devices.
    • Virtual: runs inside VMs/cloud.
  • Host-Based
    • Protects a single device.
    • Example: Windows Defender Firewall.
  • Network-Based
    • Protects an entire network or subnet.
    • Placed at perimeter or between VLANs.

Firewall Methods

  • Packet Filtering Firewall
    • Inspects packet headers (IP, port, protocol).
    • Works at Layer 3/4 (Network/Transport).
    • Basic, fast, but limited.
  • Stateful Firewall (Session-Based)
    • Tracks active sessions.
    • Allows return traffic if the session was initiated from inside.
    • More secure than stateless.
  • Next-Gen Firewall (NGFW)
    • Performs deep packet inspection.
    • Can inspect traffic at Layers 5–7 (Session, Presentation, Application).
    • Detects malware, intrusion attempts, application-level threats.
  • Web Application Firewall (WAF)
    • Specialized firewall for HTTP/HTTPS traffic.
    • Protects web apps from SQLi, XSS, CSRF, etc.
  • Unified Threat Management (UTM)
    • All-in-one appliance.
    • Combines firewall, IDS/IPS, anti-malware, VPN, NAT/PAT.
    • Easier to manage, but single point of failure.

Supporting Concepts

  • NAT (Network Address Translation)
    • Translates private IPs → public IPs.
    • Hides internal structure.
  • PAT (Port Address Translation / NAT Overload)
    • Many private IPs share one public IP.
    • Uses unique port numbers to distinguish sessions.
  • ACL (Access Control List)
    • Firewall/router rules that permit or deny traffic.
    • Based on IP, port, protocol, etc.
    • Example:
      • Switch → filters by MAC address.
      • Router → filters by IP address.
      • Firewall → filters by IP + ports/protocols.

✅ Exam Tips:

  • Packet filter = header only
  • Stateful = tracks sessions
  • NGFW = deep packet inspection (Layer 7)
  • WAF = protects websites
  • UTM = all-in-one security box
  • NAT/PAT = hide internal IPs