Network Security Philosophy & Introduction Dr. Enis Karaarslan Muğla University Computer Engineering Department Netseclab.mu.edu.tr Dr. Enis Karaarslan 1
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SECURITY PHILOSPHY 3
Computer & Network Security has similarities with the security in normal life. 4
There is no such thing as %100 Security 5
Security at the gates only, is not enough 6
A chain is only as strong as its weakest link 7
As there is no %100 security So give up? A possible solution: Use more than one chain 8
MULTI LAYER SECURITY 9
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Security x Usability 11
Value of Assets and Expenditures What is the VALUE of your asset (data, prestige )? Keep in mind that Security expenditures should not be greater than the value of the assets 12
Risk Analysis Risk analysis is essential If the risk is too low, that/some precaution(s) can be cancelled 13
False Sense of Security A false sense of security is worse than a true sense of insecurity. Solution: Never think your system is secure. 14
No Template Which Suits All There is no templates which suits all. There is a different solution for different organizations l Different needs l Different assets 15
To win a war, one must know the way Sun Tzu The Art of War 16
Security is a process, not a product. Bruce Schneier 17
MONITOR The system should be monitored for intrusions And immediate action should be taken at attacks 18
Warn The Attacker 19
Try to Buy time for Make attacking difficult for l Discovery of the attack l Take measures Make decryption difficult so that l The data is not valid or valuable any more. 20
Network Awareness Know your enemy (?) Know yourself, l know your assets l know what to protect Know your systems more than the attacker 21
FUNDAMENTALS 22
Information System and Security ATTACK SECURITY MEASURES ATTACKER VULNERABILITY INFORMATION SYSTEM USERS
Vulnerable Systems The systems are vulnerable l Mainly because of bad coding l Must be patched (but can not be done rapidly as they should) l False sense of security 24
A vulnerability timeline
The Attacker/Intruder The attacker can be called as: Lamer, intruder, attacker (wrongly used as hacker also) Also secret organizations? Also companies (serious antivirus/defence economy) 26
Hacker /Lamer /Attacker Hacker is used as attacker/lamer, in the meaning: The intruder, who gets in your system and intends to use for his/her own aims. 27
The Attacker The attackers strength is Dedication l Will not stop until he/she gets in l Can use the computer for days long sleepless l Knows the vulnerabilities of systems 28
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Network Security Assets Network Security Overall l Network Awareness l Firewall, Intrusion Detection Systems etc l More Host (Computer/Server/NW Device) Security l Physical Security l OS and Application Security l User Management Encryption 30
Firewall 31
Firewall Basics Rule based access control between networks. Software/hardware based Architecture l Static Packet Filtering l Dynamic Packet Filtering (Statefull inspection) l Application Level Protection Logging and alert capabilities 32
Encryption Encryption is the conversion of data into a form, called a ciphertext, that cannot be easily understood by unauthorized people. (Encryption x Decryption) 33
Encryption Two different methods (according to key use) l Conventional Two keys are the same l Asymetric (Public Key Encryption) Key pair (public, private) 34
Encryption To decyrpt an encrypted data l How much time? l How much Processing (Computing power)? The science which deals with encryption is Cryptology 35
END OF THE SESSION Dr. Enis Karaaslan enis.karaarslan@mu.edu.tr 36