Firewall and its purpose
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A presentation discusses different types of firewalls and how they work. Firewalls are devices that control network access by enforcing rules on transmission of data based on things like source/destination addresses and protocols. Common types include packet filters, stateful packet filters, application-level gateways, and circuit-level gateways. Firewalls can be configured in different ways depending on network needs and are used to implement access control policies to protect networks and resources.
Firewall and its purpose
- 2. FIRE
- 3. WALL
- 4. + = But does fire + wall =firewall ??? Is this definition correct?? Well not exactly
- 5. Finally, welcome to last presentation of the 8th SEM CSE
- 6. FIREWALLS Presented by- 1) Rohit Phulsunge 2) Satyendra Singh Naruka 3) Saurabh Maheswari 4) Sameer Pathak 5) Sandeep Suryawanshi
- 7. So what exaclty is a firewall?? A firewall is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass.
- 8. A diagram showing where a firewall can be placed.
- 9. History The term firewall originally referred to a wall intended to confine a fire or potential fire within a building Later uses refer to similar structures, such as the metal sheet separating the engine compartment of a vehicle or aircraft from the passenger compartment.
- 10. What does firewall do? a choke point of control and monitoring interconnects networks with differing trust imposes restrictions on network services ◦ only authorized traffic is allowed auditing and controlling access ◦ can implement alarms for abnormal behavior provide NAT & usage monitoring
- 11. Firewall Limitations cannot protect from attacks bypassing it ◦ E.g., sneaker net, utility modems, trusted organisations, trusted services (eg SSL/SSH) cannot protect against internal threats ◦ eg disgruntled or colluding employees cannot protect against transfer of all virus infected programs or files ◦ because of huge range of O/S & file types
- 12. Firewalls – Packet Filters simplest, fastest firewall component foundation of any firewall system examine each IP packet (no context) and permit or deny according to rules hence restrict access to services (ports) possible default policies ◦ that not expressly permitted is prohibited ◦ that not expressly prohibited is permitted 12
- 13. Firewalls – Packet Filters 13
- 14. Firewalls – Packet Filters 14
- 15. Attacks on Packet Filters IP address spoofing ◦ fake source address ◦ authenticate source routing attacks ◦ attacker sets a route other than default ◦ block source routed packets tiny fragment attacks ◦ split header info over several tiny packets ◦ either discard or reassemble before check 15
- 16. Firewalls – Stateful Packet Filters traditional packet filters do not examine higher layer context ◦ i.e., matching return packets with outgoing flow stateful packet filters address this need they examine each IP packet in context ◦ keep track of client-server sessions ◦ check each packet validly belongs to one they are better able to detect bogus packets out of context 16
- 17. TYPES OF FIREWALLS Packet filtering Router Application level gateway Circuit level gateway 17
- 18. Packet filtering Router Apply set of rules to IP packet *Rules for network packet Source IP Address Destination IP Address Source & Destination transport level address IP protocol field Interface 18
- 19. Application Level Gateway have application specific gateway / proxy has full access to protocol ◦ user requests service from proxy ◦ proxy validates request as legal ◦ then actions request and returns result to user ◦ can log / audit traffic at application level 19
- 20. Application Level Gateway 20
- 21. Firewalls - Circuit Level Gateway relays two TCP connections imposes security by limiting what such connections are allowed once created usually relays traffic without examining contents typically used when trust internal users by allowing general outbound connections 21
- 22. Firewalls - Circuit Level Gateway 22
- 23. Bastion Host highly secure host system runs circuit / application level gateways or provides externally accessible services potentially exposed to "hostile" elements hence is secured to withstand this ◦ hardened O/S, essential services, extra auth 23
- 24. Firewall Configurations 24
- 25. Firewall Configurations 25
- 26. Firewall Configurations 26
- 27. Access Control determines what resources users can access general model is that of access matrix with ◦ subject - active entity (user, process) ◦ object - passive entity (file or resource) ◦ access right – way object can be accessed can decompose by ◦ columns as access control lists ◦ rows as capability tickets 27
- 28. Access Control Matrix 28
- 29. Trusted Computer Systems information security is increasingly important have varying degrees of sensitivity of information ◦ military info classifications: confidential, secret, etc subjects (people or programs) have varying rights of access to objects (information) known as multilevel security ◦ subjects have maximum & current security level ◦ objects have a fixed security level classification want to consider ways of increasing confidence in systems to enforce these 29
- 30. Bell LaPadula (BLP) Model has two key policies: no read up (simple security property) ◦ a subject can only read an object if the current security level of the subject dominates (>=) the classification of the object no write down (*-property) ◦ a subject can only append/write to an object if the current security level of the subject is dominated by (<=) the classification of the object 30
- 31. Reference Monitor 31
- 32. Summary have considered: ◦ firewalls ◦ types of firewalls ◦ configurations ◦ access control ◦ trusted systems 32