1. Network Security: Pentingnya Keamanan Komputer
Source from :Computer Network Research Group ITB

2. Perspective ... less then 200 security incident in 1989.
about 400 in 1989.
about 1400 in 1993.
estimated more than 2241 in 1994.
Nobody knows the correct statistics on how many attacks are actually detected by the sites broken into.

3. Survey Dan Farmer (Dec96)
1700 web sites:
60% vurnelable.
9-24%terancam jika satu bug dari service daemon (ftpd, httpd / sendmail) ditemukan.
Serangan pada % sites di netralisir menggunakan denial-of-service

4. Statistik Serangan

5. Resiko Serangan

6. Sumber Serangan

7. Aktifitas Serangan

8. Serangan di Internet
Approx hosts are connected to Internet (end1996)
US DoD serangan / tahun.
Serangan pada Rome Laboratory.

9. Network Security
usaha untuk mencegah seseorang melakukan tindakan-tindakan yang tidak kita inginkan pada komputer, perangkat lunak, dan piranti yang ada di dalamnya sehingga semuanya tetap dalam keadaan ideal yang kita inginkan’

10. Layout Firewall

11. What are you trying to protect?
Your Data.
Your Resources.
Your Reputation.

12. What Are You Trying To Protect Against?
Type of attacks
Intrusion.
Denial of Service.
Information Theft.

13. Type of Attackers Joyriders. Vandals. Score Keepers.
Spies (Industrial & Otherwise).
Stupidity & Accidents.

14. Security Policy
‘satu keputusan yang menentukan batasan-batasan tindakan-tindakan yang bisa dilakukan dan balasan apabila terjadi pelanggaran batasan-batasan yang ada untuk mencapai satu tujuan tertentu’

15. Objectives
Secrecy
Data Integrity
Availability

16. Step Security Policy Apa yang boleh / tidak boleh.
Prediksi resiko & biaya (start dengan bug).
Tentukan objek yang di lindungi.
Tentukan bentuk ancaman & serangan:
unauthorized access.
Disclosure information.
Denial of service.

17. Step ... Perhatikan kelemahan system: Optimasi Cost / Performance.
authentication.
Password sharing.
Penggunaan password yang mudah di tebak.
Software bug.
Optimasi Cost / Performance.

18. Manusia ...
Tanggung Jawab.
Komitmen.

19. Design Security Policy
Kerahasiaan (Secrecy)
Integritas Data
Availability
Konsistensi
Kontrol Identifikasi & Authentikasi
Monitoring & Logging

20. Prinsip ...
Hak minimum
Kurangi jumlah komponen

21. How Can You Protect Your Site
No Security.
Security Through Obscurity.
Host Security.
Network Security.
No Security Model Can Do It All.

22. What Can A Firewall Do? A firewall is a focus for security decisions.
A firewall can enforce security policy.
A firewall can log Internet activity efficiently.
A firewall limits your exposure.

23. What Can’t A Firewall Do?
A firewall can’t protect you against malicious insiders.
A firewall can’t protect you against connections that don’t go through it.
A firewall can’t protect against completely new threats.
A firewall can’t protect against viruses.

24. List of A Must Secure Internet Services
Electronic mail (SMTP).
File Transfer (FTP).
Usenet News (NNTP).
Remote Terminal Access (Telnet).
World Wide Web Access (HTTP).
Hostname / Address lookup (DNS).

25. Security Strategies. Least Privilege.
Defense in Depth (multiple security mechanism).
Choke Point forces attackers to use a narrow channel.
Weakest Link.
Fail-Safe Stance.
Diversity of Defense.
Simplicity.

26. Building Firewalls

27. Some Firewall Definitions
A component or set of components that restricts access between a protected network and the Internet, or between other sets of networks.
Host
A computer system attached to a network.

28. Firewall Def’s Cont’ .. Bastion Host Dual-homed host
A computer system that must be highly secured because it is vulnerable to attack, usually because it is exposed to the Internet and is a main point of contact for users of internal networks.
Dual-homed host
A general-purpose computer system that has at least two network interfaces (or homes).

29. Firewall Def’s Cont ... Packet. Packet filtering. Perimeter network.
The fundamental unit of communication on the Internet.
Packet filtering.
The action a device takes to selectively control the flow of data to and from a network.
Perimeter network.
a network added between a protected network and external network, to provide additional layer of security.

30. Firewall Def’s Cont ... Proxy Server
A program that deals with external servers on behalf of internal clients. Proxy client talk to proxy servers, which relay approved client requests on to real servers,and relay answer back to clients.

31. Packet Filtering

32. Proxy Services

33. Screened Host Architecture

34. De-Militarized Zone Architecture

35. DMZ With Two Bastion Hosts

36. It’s OK Merge Interior & Exterior Router
Merge Bastion Host & Exterior Router
Use Mutiple Exterior Router
Have Multiple Perimeter Network
Use Dual -Homed Hosts & Screened Subnets

37. It’s Dangerous Use Multiple Interior Router
Merge Bastion Host and Interior Router

38. Private IP Address Use within Internal Network Reference RFC 1597
IP address alocation:
Class A: 10.x.x.x
Class B: x.x x.x
Class C: x x

39. Bastion Host It is our presence in Internet. Keep it simple.
Be prepared for the bastion host to be compromised.

40. Special Kinds of Bastion Hosts
Nonrouting Dual-Homed Hosts.
Victim Machine.
Internal Bastion Hosts.

41. Choosing A Bastion Host
What Operating System?
Unix
How Fast a Machine?
386-based UNIX.
MicroVAX II
Sun-3

42. Proxy Systems Why Proxying?
Proxy systems deal with the insecurity problems by avoiding user logins on the dual-homed host and by forcing connections through controlled software.
It’s also impossible for anybody to install uncontrolled software to reach Internet; the proxy acts as a control point.

43. Proxy - Reality & Illusion

44. Advantages of Proxying
Proxy services allow users to access Internet services “directly”
Proxy services are good at logging.

45. Disadvantages of Proxying
Proxy services lag behind non-proxied services.
Proxy services may require different servers for each service.
Proxy services usually require modifications to clients, procedures, or both.
Proxy services aren’t workable for some services.
Proxy services don’t protect you from all protocol weaknesses.

46. Proxying without a Proxy Server
Store-and-Forward services naturally support proxying.
Examples:
(SMTP).
News (NNTP).
Time (NTP).

47. Internet Resources on Security Issues

48. WWW Pages http://www.telstra.com.au/info/security.html

49. Mailing Lists firewalls@greatcircle.com fwall-users@tis.com
ftp://ftp.greatcircle.com/pub/firewalls/
ftp://net.tamu.edu/pub/security/lists/academic-firewalls

50. Newsgroups comp.security.announce. comp.security.unix.
comp.security.misc.
comp.security.firewalls.
alt.security.
comp.admin.policy.
comp.protocols.tcp-ip.
comp.unix.admin.
comp.unix.wizards

51. Summary
In these dangerous times, firewalls are the best way to keep your site secure.
Although you’ve got to include other tipes of security in the mix, if you’re serious about connecting to the Internet, firewall should be at the very center of your security plans.