Lecture 21: Internet Security Intro to IT COSC1078 Introduction to Information Technology Lecture 21 Internet Security James Harland

Lecture 21: Internet SecurityIntro to IT Introduction to IT 1-4 Introduction, Images, Audio, Video 5-6 Computer Fundamentals Assignment 1, WebLearn Test 1 7 Review 8 Operating Systems WebLearn Test 2 9 Operating Systems Assignment 2 10 Internet 11 Internet & Security WebLearn Test 3 12 Future of ITAssignment 3, Peer and Self Assessment

Lecture 21: Internet SecurityIntro to IT Intro to IT Schedule WeekLecture 1Lecture 2 11Internet ProtocolsInternet Security 12Future of IT Review by request or more Future of IT 13Mock Exam Wednesday 2 nd June

Lecture 21: Internet SecurityIntro to IT Overview  Questions?  Mock Exam  Assignment 3  Internet Security  Questions?

Lecture 21: Internet SecurityIntro to IT Mock Exam  (TBC) on Wednesday 2 rd June in  Bring your own paper, pens, etc.  No calculators allowed  Answers will be available from me when you leave Schedule (times to be confirmed):  Access to room  Reading time commences  Writing time commences  Exam concludes

Lecture 21: Internet SecurityIntro to IT Assignment 3 Review (re-) answer What is IT? questions from Tutorial 1 Identify difficult parts of the course Suggest new questions Include favourites from Assignments 1 and 2 Reflect Answer reflection questions from tutorials Research Write about a particular IT topic of your choice (5-6 paragraphs)

Lecture 19: Internet: ImagesIntro to IT Internet Lisa? Hi Dad! Listen! Lisa? Hi Dad! Listen!

Lecture 21: Internet SecurityIntro to IT Internet Structure Application Transport Network Link Network Link Mordor sucks! 2 dor1 Mor 3 suc4 ks! dor1 Mor 3 suc4 ks! Mordor sucks!

Lecture 21: Internet SecurityIntro to IT Internet Structure 1 Mor 1 6 6

Lecture 21: Internet SecurityIntro to IT Network Layer (Internet Protocol)  Real intelligence is in the network layer  Adds next destination to packet  Not complete list of addresses  Sends to next destination  Retrieves final destination packets for this node  Passes them to the transport layer  Routing tables can be updated when disconnections occur  Hop counts used to stop endless looping

Lecture 21: Internet SecurityIntro to IT Transport layer  Transmission Control Protocol (TCP) often used  User Datagram Protocol (UDP) becoming more common  TCP Establishes connection first Send and wait for acknowledgement Reliable Can adjust flow control to avoid congestion Often best for (which is not real-time) Older

Lecture 21: Internet SecurityIntro to IT Transport layer  UDP Doesn’t establish connection Just sends and forget Efficient No congestion adjustment Works well for DNS lookup Often used for Voice over Internet Protocol (VoIP) applications such as Skype

Lecture 21: Internet SecurityIntro to IT Internet addresses  Unique 32-bit identifier (up to 4,294,967,296)  Soon to become 128-bit identifier  Managed by Internet Corporation for Assigned Names and Numbers (ICANN)  ISPs get “blocks” of addresses  32-bit string represented as N 1.N 2.N 3.N 4 where N i is in the range  means

Lecture 21: Internet SecurityIntro to IT Internet addresses  Dotted decimal notation is still not very kind to humans …  -> ??.??.??.??  Translation done by name servers which look up the Domain Name System (DNS)  Domains such as rmit.edu.au can be structured by the domain owner (eg goanna.cs.rmit.edu.au)

Lecture 21: Internet SecurityIntro to IT Internet Security password patch spam fire wall virus war driving key logger proxy wormphishing Trojan horse

Security vs access  It is always a trade-off (a balance between two competing forces)  More security means less access  More access means less security  Redundancy can be either fatal or vital  Nothing is perfect!

Freedom vs security  `Everything which is not forbidden is allowed’ -- Principle of English Law  `Everything which is not allowed is forbidden’ -- Common security principle  `Anything not mandatory is forbidden’ -- “military policy”  `Anything not forbidden is compulsory’ (??) — T.H. White (The Once and Future King)

Lecture 21: Internet SecurityIntro to IT Conclusion  Work on Assignment 3  Check whether your security defenses are up to date