Lecture 01 Firewalls Firewall is a Hardware or

Lecture - 01 Firewalls

Firewall is a Hardware or a Software to Defend Computer Networks Like a Real Wall with Fire on it; was used to Defend Classical Fortress in War In Computer Networks Firewall can also be termed as Opposite of a Routers have all Network Ports OPEN by Default Firewalls have all Network Ports CLOSED by Default

Firewall n o i at r t e en P o Firewall is a Central Point of Network for Control and Monitoring t e n u m m I s i f l Interconnects networks with different Trust Levels e s t i ll a w e r i F t Regularly Controls the Network Services and allows authorized Traffic only a h t d e m u s s Ensures Regulary. Monitoring & Auditing to Control Access to generate Alarms & a l l a Violation is Detected a Alerts whenever r e n e g s i t I Firewall is a Line of Defence in the Network and generally called Perimeter Defense

Taxonomy of Firewalls Based on Protocol Level Controls: - a b m s i n ha Packet Filtering Circuit Gateways h o d p y r nc c e m n tio E e av s l l a w Application Gateways e r i F e m o S o d se Combination of above all is called Dynamic Packet Filter 2 1 n it B 8 S E A

Firewalls – Packet Filters Internet Packet Filtering Your Network

OSI Model - 7 Layers Application Presentation Session Transport Network Data Link Physical

IP Source Address Firewalls – Packet Filters IP Destination Address Protocol Header like TCP, UDP, ICMP TCP Source & Destination Ports UDP Source & Destination Ports TCP Flags (SYN, ACK, FIN, RST, PSH) ICMP Message Type Own Policies & Rules 7

Firewalls – Packet Filters Example rk o etw n o s N e th t e k c Pa g n i o g t unot carried out Deep Packet Inspection O s a ll e w Packets are following the Rules s a ng i m o Packets from Registered Server c n I e th s r li te Packets from known Sever e r i F F l l wa DNS uses Port 53 8

Usage of Packet Filters Filtering - Incoming or Outgoing Interfaces Ingress filtering of spoofed IP addresses Egress filtering of unauthorized Data

Usage of Packet Filters Permits or Denies Certain Services & Requires intimate knowledge of : TCP Port utilization UDP Port utilization Complete requirements of Operating System (OS)

How to Configure a Packet Filter Make a Comprehensive Security Policy Specify Allowable Packets in Terms of Logical Expressions on Packet Fields Rewrite expressions in syntax supported by the Firewall

General Rules - Least Privilege All Ports Blocked except the Permitted ones All Protocols Blocked except the Permitted ones All Services Blocked except the Permitted ones If something is not clearly understood; Block it

What the Students can DO They are enabled for a Job in Cyber Security Business oriented & Start Ups can make their own Fire Walls & Routers and Market them at a much lower price How to make a Fire Wall by installing specific type of Linux How to market your own made Fire Walls

How to make a Firewall To turn your old PC into a firewall you’ll need the following items An old PC tower A monitor An additional network card

How to make a Firewall You will also need an open source software distribution to turn your PC into a firewall. Top three open source firewall distributions for Linux are given below IP Cop (http: //www. ipcop. org) Smooth. Wall (http: //www. smoothwall. org) pf. Sense (https: //www. pfsense. org)

Why to make a Firewall Advice by Bruce Schneier - Marketing Points Find Cyber Security in the Hardware made by small companies Find Cyber Security in Mathematics Reliance on the Open Source Software

Way forward - Firewalls Make & Practice your own Firewall Use old PC, Arduino, Raspberry Pi or FPGAS In case of bulk orders go for ASIC Use simmilar techniques for Routers

Questions & Discussion