My name is Jong-Moon Chung, and I'm a Professor at Yonsei University. Welcome to the course Introduction to TCP/IP. This course includes five major chapters, and they are listed right here: My PC's Internet and Gateway, TCP/IP Protocol, Internet Routing and Functions, Internet Security, Wireshark Internet Project. In the first chapter, my PC's Internet and gateway, it talks about how your PC is connected to the Internet and what are the basic configurations. This is the best way to learn how the Internet actually works. So, therefore, I use that as a tool for you to see how your computer is connected to the Internet, which you've been using everyday. So, we start off with my PC's Internet setup. Then we go into the second one, which is the automatic Internet setup using DHCP, which is the dynamic host configuration protocol. Then the IP gateway and router configuration. Then, based on that configuration, we're going to see how the IP routing table is set up and then how it's used when a packet comes into the router or the gateway. How is that routing table used to find which way to send it out? For example, in this chapter, we will go into the actual configuration setup in your personal computer. We will look at these options that are set up. This is basically how you use your Internet. What do these numbers mean? What do these options that are selected, what do they mean? I'll teach you all about that. In addition, we'll study about routers. We will study about this example, which has four different connections to four different interfaces that are used on the gateway, on the router. Inside, there is a routing table in the middle. We are connecting a large number of computers, where we have four different rooms connecting a total of 175 computers. Then, one interface port is connected to the Internet. How do you set up a basic routing table, and how does it work when a packet comes in to search down this information to decide where it's going to be sent out by the router? Now, every computer, every PC that exists is connected to a default router. Now, in that default router, how is that setup? That's basically what we're going to study about. Because your PC sends all of its packets to that default router to connect to the Internet or other computers, and every packet that you receive on your personal computer or laptop computer comes from that default router to you. So, that router is so important. So, that's why we're going to study about how it all works in very simple terms. Then in the TCP/IP protocol lecture, we're going to study about the OSI seven-layer model and the TCP/IP five-layer model. Also, network operations and the TCP/IP layers. What and how do they work? In addition, what are their networking functions? As well as, we'll study some details on IPv4 and IPv6, which also include the CIDR notation, which is classless inter-domain routing. In addition, we'll study on the protocol structure of UDP and TCP. For example, the TCP/IP protocol structure five-layer model is over there. Corresponding to each layer, these are the protocols and their functions that we have. As you can see, down there, Ethernet, Wi-Fi, Bluetooth, and 3G, as well as 4G LTE communications, these are the options that we've been always using. So, therefore, it's time to learn how this all works together. Then in the next chapter about Internet routing and functions, we'll study about IGP and EGP, which include BGP4 protocol. We'll study about the OSPF routing technology, then ARP, NAT, RPC, FTP, and email technology. For example, in this chapter, one of the things that we'll study about, is the OSPF shortest path tree routing. This is the routing technology that is used in the Internet. So, you've been using it your entire life. You might as well know a little bit about how it actually works, and that's what this course is about. Then we'll go into Internet security. It's so important. So, there's so many security attacks, and there's so many defense technologies. So, which ones should we look into first? Well, we'll go off of the ones that are the top ranking, the most famous ones of all. We'll start off with the ranking table itself, and then we'll see what is actually going on. Then, what are the growing security and thread issues that we need to look into? Then we'll go into the Internet and cyber attacks, where we will cover phishing, denial of service, DoS, distributed denial of service, overflow, man-in-the-middle attacks, and SQL injection type techniques. Now, we will also look into the Internet security and protection techniques, which include firewall, intrusion detection system, IDS, TLS, WEP, and secure shell technology. For example, just looking at the ranking of the most frequent types of attacks that occur over the Internet, we'll study about them in this list order of importance. Then, to wrap this course up, we have a very easy project that we're going to be doing together, and that is Wireshark Internet project. First, I'm going to show you how to install Wireshark and then, how to check your IP configuration on your computer. Now, this function of IP config and using your command Window, these type of things have been always on your computer, and now you'll get to learn how to use them. Then, using the Wireshark program that we installed, we're going to use it to analyze the overall Internet connections that we've been using so far. For example, one snapshot of a Wireshark capture of actual action that's going on through the Internet connection and your PC is something that's demonstrated here, where you can see the source IP address, destination IP address, including the TCP handshake, which is a handshake operation like this. In addition, the TLS security handshake operations down there, are also shown. We will be making connections and actually downloading a file from a Google Drive or a Baidu Drive, and that will be the test experiment that we will do. So, therefore, these are the contents included in this course, introduction to TCP/IP. I welcome you to join me in this course. Thank you very much.