Managing Digital Networks and Security > Digital networks > Networking protocols and devices
- The manner in which they are connected and the different standards and methods that have been used is quite complex.
- What we will focus on are the key issues that managers need to understand to make decisions about networks and innovate with them.
- The fundamental building blocks of the Internet are a bunch of standards called protocols.
- Protocols are agreed-upon methods and standards by which different parts of networks exchange data.
- Think of a protocol as a convention, as a way of communicating.
- Guru: You mean being rude is part of the protocol? Prof: Yes, politeness and rudeness are culturally defined.
- The Internet is built on many protocols: TCP, IP, HTTP, UDP and so on.
- Those who engineer the Internet agree that they will work with these standards and then build hardware and software accordingly.
- What you see on the slide is an animation of the TCP protocol.
- Anyone who understands them can build devices or software or services with these protocols.
- The Internet has grown so massively because of the open nature of these protocols.
- The network will have many laptops, desktops and mobile devices connected to it.
- Within the LAN are also other devices called Hubs and Switches.
Managing Digital Networks and Security > Digital networks > How the packet flows in a network
- Just like a mail packet, each network packet consists of an address and the content it is carrying.
- Each packet contains parts of the email message and also the address to which it is being sent.
- So packets are created for each type of message on the Internet, with content and address information.
- The job of the hubs and switches is to direct or route the packets within the network.
- When packets have to go out of the local network to the Internet, also called the wide area network or the WAN, then the router is involved.
- A packet will originate in a client on one network, go through hubs and switches… …then through the router on to the Internet and then to the destination network’s router… …through the switches and hubs to the destination Internet server.
- Basically, a client asks for services or information on the Internet, and a server provides those services.
Managing Digital Networks and Security > Digital networks > Network Layers
- Each packet goes through a bunch of layers: once when it is being prepared to be sent, and once when it is being received.
- Packets are usually originated at the Application layer, by programs such as email and the browser.
- Then the packet is moved through the Network, Data Link and Physical layers that add further information… …on how, what and where the information has to go, and actually moves the information.
- Information always moves in 0s and 1s, which are known as bits.
- On the receiving side, the packets again move up the layers to the Application layer program that reads or displays the information.
- Those who are designing and building physical components, at the Physical layer, do not have to worry about how email will work.
- Thousands of engineers and firms work on application or protocol development… …to improve services at different layers, without having to bother about other layers.
Managing Digital Networks and Security > Digital networks > Network management
- Managers have to make sure that the architecture allows for future growth and also… …for innovation.
- If they… …design carefully, they can make sure that when their business and needs grow, their network architecture can scale accordingly.
- The internet is essentially built up with open standards and open source software.
- It is… …easy to find and use open source software for network elements.
- Open source software enables innovation and scale-up.
- Organisations have to think of… …how fast and efficient their networks are, and this is based on a parameter called bandwidth.
- Security levels have to be decided by the business and competitive needs of the organisation.
Managing Digital Networks and Security > Security > Security management
- The biggest threat to innovation with IT is security.
- For managing security, organisations have to worry about four major issues: confidentiality, authentication, message integrity, and access.
- Message integrity means that the system assures that the message received is complete.
- For organisations, it is essential that they manage these four issues and their security environment will be fine.
- Let us look at some of these security issues and how to handle them.
Managing Digital Networks and Security > Security > Phishing and identity theft
- You will quickly note that it is the site of the Indian Income Tax Department.
- What is the difference in these images? Please pause the video here and go back and see the old image again, if you want.
- Phishing is a means of luring customers to sites from which to extract information from them.
- There are many instances where fake bank sites are created… …where customers are encouraged to log in, and then their login and password information is collected.
- Prof: Very good, Guru! That is indeed the best way to find out if the site you are using is authentic or not.
- Fake sites may imitate the look of the real site, but the Uniform Resource Locator or URL… …which is the address of the site cannot be easily faked.
- Phishing and identity theft is one of the main security problems facing firms that have customers or clients log in to their site.
- Customers are not always careful with the password and with checking the authenticity of sites.
- Guru, do you have the name of a friend, a family member or pet in any of your passwords? Guru: Of course, how else will I remember my password? Prof: So, whose name do you use? Guru: My pet goldfish – Chetu.
- They pose innocent questions to find out names of your family members and friends.
Managing Digital Networks and Security > Security > Viruses, Worms and Trojans
- Prof: Some of the biggest security threats to organisations come from viruses, worms and trojans.
- Viruses are computer programs that are malicious in nature, and enter computer systems without the user’s awareness.
- Their intent usually is to do harm by corrupting files and destroying data.
- Millions of viruses have been written, many of which infect Windows computers and wreak havoc.
- Worms, on the other hand, are computer programs that enter computer networks and simply multiply.
- Worms do not harm files or destroy data; they are meant to choke networks.
- An organisation infected by a worm will suddenly find that its networks are clogged and message flow is restricted.
- Trojans are programs that are a variant of viruses and worms, mainly because they are targeted at specific users or organisations.
- A trojan software enters a network and keeps multiplying and moving through the network.
- Their intent is to seek out particular systems or users, and then they either steal data or destroy files.
- It is believed that the USA and Israel wanted to target Iran, and hence wrote the software to destroy Iran’s nuclear reactors.
- Cracking is the act of breaking into computers or computer networks illegally.
- In response to these, they take many measures, which include using Firewalls, using encryption and virtual private networks.
Managing Digital Networks and Security > Security > Denial of Service attack
- These attacks are designed to exploit a feature of some protocols of the Internet, called Transmission Control Protocol or TCP. In these protocols, when a-one server sends a message to another server to request service… …the responding server has to first respond with an acknowledgement.
- After sending the acknowledgement, the responding server waits a certain amount of time… …and waits for the message from the sender to arrive.
- The way crackers exploit this protocol is by sending out the first request, forcing the receiving servers to respond and then wait.
- The receiving server waits for a certain amount of time and then breaks the connection, or times out.
- Now if the attackers do-do this often enough, the responding server will send all-spend all its time… …waiting for messages that do not arrive, and legitimate customers will face delays.
Managing Digital Networks and Security > Security > Countermeasures
- Prof: Public-key cryptography is a means of sending messages in a disguised or coded manner.
- Most keys are much more complex, using a lot of complex mathematics so that it is almost impossible to find out what the key is.
- In public-key cryptography, the message is coded with two keys.
- So if you have a person A sending a message to person B, we can call them Alok and Bani… …Alok can take Bani’s public key, code or encrypt his message and send it to Bani.
- Bani can then encode or decrypt the message with the private key that she has.
- The important point here is that even if someone grabs hold of the coded message, they will not be able to read it without the private key.
- When Alok sends a message to Bani, using Bani’s public key, Bani is assured that nobody has read the message.
- What Bani is not sure of is if someone has tampered with the message.
- Consider a situation where Alok gets Bani’s public key and encodes his message with it.
- His message is “I love you – Alok.” Now, suppose there is an evil guy, Chetan, who is jealous of Alok.
- He could intercept Alok’s message, then he could take Bani’s public key and write his own message “I hate you – Alok”, and send it to Bani.
- Bani would not know that the message is not from Alok, when she reads it.
- Then he first encrypts the message with his private key.
- He encrypts the message again with Bani’s public key and sends it to her.
- What Bani has to do is first open the message with her private key.
- So she has to get Alok’s public key and open it.
- Public and private keys work in pairs, one locks and the other opens.
Section 2: Managing Digital Networks and Security