firewalls.pdf
- 2. Firewalls Implemented • Hardware • Software • Combination of (Hardware and Software) Types • Host-based (Personal) • Network
- 3. Things we can do with firewalls • All data traffic from outside is separated from inside the firewall • We could allow only traffic coming to port 80 to be allowed. • We could allow all traffic except traffic to port 80 to be allowed. • No ftp traffic allowed (unencrypted passwords)
- 4. Network firewall • Use a firewall device (usually a computer running firewall software) • Install 2 interfaces. • 1) connected to our internal network interface • 2) connected to the external network or internet • All data going to and from the internet travels though the firewall following rules that decide if traffic can or can not go though • Places at the boundary of the trusted network
- 5. Host based (Personal) Firewall Software installed on one host (computer) that checks all traffic to- and-from that system.
- 6. Layers of firewalls • Several firewalls can be used that prohibit traffic from passing though. This makes it more difficult for hackers to get though. • Most operating systems come with host based firewalls and right there if you have a network based fire wall and use an OS with firewalls, you have 2 layers of firewalls.
- 7. Firewalls read IP packets • Network layer data such as IP address and Port Numbers of the source and destination are read and checked against internal tables. • Host based firewalls are usually application firewalls. • Network based firewalls are usually Packet Filters.
- 8. Policies for traffic going through • Allow Policy – all packets that do not meet the “allow criteria” are blocked. block everything and open holes • Deny Policy - all packets that meet the “deny criteria” are blocked. block nothing and close holes
- 9. Detections of a possible intrusion
- 10. DNS (Domain Name System) • A system that maps IP addresses to URL names • www.facebook.com = 31.13.80.36 • www.amazon.com = 13.33.60.247 If you firewall blocks www.facebook.com and you can get to a different ip address to a different facebook server, you can get in directly using the unblocked IP address.
- 11. Hubs, Switches, and Routers • Hubs – connect a few computers together. All messages sent out of one computer is broadcasted (spamed) to all computer connected to the hub. • Switch – can be used to join switched LANs • Router – connects at least 2 networks • Bridge – connects two networks (LANs) to create 1 network.
- 12. Routers, Switched, Hubs and OSI
- 13. VPN (Virtual Private Network)
- 14. VPN (Virtual Private Network) • A virtual private network (VPN) extends a private network across a public network, and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. • VPNs may allow employees to securely access a corporate intranet while located outside the office • A VPN is created by establishing a virtual point-to-point connection through the use of dedicated connections, virtual tunneling protocols, or traffic encryption
- 15. VPN pros and cons Pros: • VPNs can bypass some firewall content restrictions and censorship. Cons: • Speed is slowed down: • New link to communication path. You VPN Destination • Encryption / decryption algorithms • You compete with other users of the VPN server. • VPN cost about $60/year (Free ones are very slow)