 Hello everyone, welcome to the session on Telnet Learning Outcomes. At the end of this session, students will be able to describe the concept of Telnet protocol and students will be able to state the concept of NVTI embedding, content, Telnet protocol, time sharing environment, network virtual terminal embedding. These are the topics I am going to cover in this video about Telnet. Telnet is a terminal network. Here I have mentioned some capital letters T, E and L in this word N, E, T. These capital letters can combine together you can call it is a telnet, terminal network, abbreviation of telnet is a terminal network. It is a general purpose client server application program. It can be used to share the data between two users that is client and server. In the telnet, if the user is there in one LAN, if he wants to access the data from other LAN, then that time the user can go to the telnet concept. In the time sharing environment, all of the processing must be done by the central computer. It means if the client is there in one place and server is there in the other places, then that time user can use a telnet. In the time sharing environment, if the user wants to access any data, that time the user must have an authorized person to that particular network. It means the user must have the some you authorize credential like login, ID and password. Then that time the whatever the user can type the data, it can goes to the computer, the computer can echo to the monitor, it can show the data to the user. Based on this one only they have given what type of users or user credential need. Here login, first the user should how to login, it may be the local login or it may be the remote login. First the user how to login, then data it should be the username and password. After getting that it can go to the they want to go to the local login, they can go to the local login or it may they may go to the remote login. The users are part of the system with some rights to access the resource. It means they have to some they have some authorized data that is local login and remote login. Let us see one by one in detail. First one is local login. When a user logs into a local time sharing system it is called local login. It means when a user is there logged in a single LAN or the user all the systems are connected to the single LAN that time or local machine then we can call it as a local login. Here the operating system may assign special meanings to special characters. For example in Unix some combination of characters have special meaning such as control z and control c. Just here I have taken only two examples that are control z and control c. These two special combination of characters can give a different meaning in different operating system. Here I have taken the example of the operating system is in Unix. In the Unix we have to use the control z and control c. These two are the special combination of characters. These like this there are so many special combination of characters are there. For printing we have to use the control p, control z, control y, control s and then control c also we have to use for different purpose. And these special combination of characters can give different meaning in different operating system. Different operating system like Unix or Disco operating system LionX. This is a block diagram of local login. In the local login whatever in through this terminal the user can types the data the terminal the user connection between user and the computer is in terminal. The terminal may be a the intermediate device may be the keyboard mouse and printer through keyboard user is typing some data that data will goes to the operating system. The terminal driver is an operating system here the data whatever the data they want to transfer to the users that is application program that same data will forward it to the application users or end users. Here the local machine all the systems are connected in a single LAN. When that time there is no need to use any other different format then that time the user can type the data it will goes to the operating system. This can echo to the or it can send it to the application users or end users in the local login. Next one is remote login. In the remote login when a user want to access an application program or utility located on a remote machine. He or she performs remote login it means if one user is there in one LAN then he wants to access the data from other LAN that plan or that system is not there in that particular range and that time we have to go to the remote login concept. The character are sent to the telnet client which transforms the characters to a universal character set called NVT that is network virtual terminal characters are delivers them to the local TCP IP stack. Here this is an block diagram of remote login. Here the network login. Here this part we have already discussed in a local login. How what is the difference we will discuss in the next part. Here just you have to see the how we have to work in a remote login. Through terminal the user can types the data the data may be any special combination of characters that special combination of characters or normal data the user can send it to the terminal driver that is operating system that data will goes to the telnet client. Whatever the perform whatever the work or task they how to perform they can perform a perform in a telnet client. After performing the task they can send it to the TCP IP stack that is TCP IP data link layer and then physical they can perform some work in this one and then after that that data will send it to the receiver side through internet. In the internet through internet after receiving the data in the receiver side the receiver user I mean telnet server can access the data in the sender side directly the data goes to the TCP IP stack to the receiver side through internet. After receiving the data in the receiver side the server can perform some task and then they can before transmitting or before displaying the data to the receiver side user or end user they can use one more part that is this one that is pseudo terminal driver is a software it can be used to converting the data according to the end user requirement. Here just now we have discussed in the local login control C control P control Z these some special combination of characters then can give the different meaning in different operating system. It means here this one is a different operating system or this one is separate user here is also some separate users are there here this user is using for example this user is using Windows XP and this user is using Windows Linux or Unix in that times while sending the data or special combination of characters from this user to this user that time the data special combination of characters can give the different meaning in both the operating system. To converting or we have to make the data same format here they have used whatever the combination they have used the same meaning they want to give in the receiver side users it means and that time we have to use a pseudo terminal driver this is a software it can converts the data according to the user requirement of the receiver side. This is a remote login concept. Next thing can write it can contains one question what is the difference between or compare the local login and remote login. Previously just we have discussed how it can work exactly what are the difference between those two login remote login and local login. Now pass the video and answer the question answer for the above question comparison between local login and remote login in the local login the user can login locally and then they can send the data here we have to use a concept only single line in the single line only the user can send the data and issue the data and then here whatever the special combination of character they have used the same meaning can give and then there is no need to use any other different lands and then if the user want to send from land to land it means they can go to the remote here file in a remote login the user logs into a remote machine when the user wants to access an application program or utility located on a remote machine and connect it to or gate computer through internet. In a remote login it is significant because it shows the how the internet can provide interactive services. Instead remote login permits a user to interact with a program to that turns on a remote computer it means here in the local login we have to use only single line in the remote login concept we have to use the internet while passing the data from one machine to another machine. In the local login we won't use any TCP IP stack in the receiver machine we have to use the TCP IP stack for transmitting the data. Next one is NVET that is network virtual terminal. What is this one? The network virtual terminal can be used to converting the data from one form to the other form that means what is that the mechanism to access a remote computer is complex because every computer and its operating system accept a special combination of characters as a token in that time what we have to do. For example the end of the file token is computer running the DOS that is DOS OS is control Z while the UNIX OS we have to recognize that control D. In the previous PPTA we have discussed about different operating system can perform different meaning here some special combination of characters that control Z and then in this OS it can use the end of the file the same special combination of characters we are using UNIX OS it means it is not possible to give the same meaning because it can give the different meaning again we have to use some again different special combination of characters that is control D. Here control D and control Z can use the same meaning but different operating system how it is it means this end of the file and then here end of the file can use the same meaning. Here this is the NVT block diagram here network terminal net telnet client and then telnet server here is also local character set is there this data we can send it to the telnet client this telnet client can checks the data through internet that NVT character same character they forward it to the receiver side the receiver can perform the operations then they can send it to the remote computer character set that is pseudo terminal driver this driver can convert the data according to the end user data. Next embedding is the mapping of data how we have to telnet uses only one TCP connection the server uses well-known port number 23 and the client uses the appameral port number and the well-known port number the range is 0 2 1 0 2 3 and then appameral port number is 1 0 2 4 2 6 double 5 3 5 range is there the client well-known port number we have to use in the client side and the appameral port number we have to use in the ratio or side the same connection is used for sending both data and control just example here in the embedding instead of sending the data cat file 1 they have send the cat file a then that time we have to use some in the windows directly we have to use a backspace but here we have to use instead of cat file 1 we have to use cat file a backspace 1 that can replace it to the cat file a to cat file 1. The default implementation is telnet user cannot edit locally now editing is done at the remote center only embedding the default implementation done by the telnet so embedding concept how we have to embed and then instead of sending the cat file a and then we have to use these two special combination of characters isc and ec to converting the data these are the references I have used for preparing the above ppt thank you