 Hello everyone and welcome to the session on controlling server, learning outcome. At the end of the session students will be able to describe the concept of controlling the server and students will be able to state the concept of out-of-band signaling content, controlling the server, out-of-band signaling, escape characters and mode-of operations. These are the topics I am going to cover in this video about controlling the server. When we have to use the concept of controlling the server it means when user, client is there in different places and server is there in different places then that time the client want to control the server machine information it means then that time we have to use the concept of controlling the server means when an application program running on the local computer special characters are used to interpret the program it means if the client is there in one system and server is in other places to control the data or program in the remote places then that time we have to use this one and that time here in the locally we generally we can use the control C, control Z and control Y these are some special combination of characters we have to use some different purposes and look in generally if the local machine if a client is using that machine is there in infinite loop state it means directly we can use a break statement break button and all those things to control that if the server machine is there in infinite then how we have to control that that concept it is there in a controlling the server when a program is running on a remote computer these control characters are sent to the remote machine to control the or to break the infinite loop or any problem in the server side ok some of the characters that can send to the server to control the application program that is running on the remote machine ok some of the characters that can send to the server controlling the server application program that is running on the server that is some control characters are there that control characters can be used for different purpose purpose that are IP AO, AYT, EC, AL these are the characters and decimal here and then binary values and what is the meaning of that controlling the server or control characters here for IP character we have to use the decimal value that is 2 double 4 is a binary value I mean is interrupt the process and then AO is in 245 binary value of this one is this and then about the output and then AYT is our decimal value is 246 this is a binary value and then meaning is are you there and then EC 247 erase the last character EL decimal value is in 248 and then this is an binary value and then erase line ok why we have to use that it is a first one is IP that is interrupt the process when a program is being run locally the user can interrupt the program by you if for example I said in the last PPT it means in this program is there infinite loop then that time we have to use some special combination of characters to control or to break the infinite loop program it means control C we have to use to break in in a local machine the same process happened in the local remote machine then what we have to use that is it and then AY that AO that is about output same as IP but it allows the process to continue without creating output it just it means infinite loop that we would get any output from that program directly it can the process is there infinite repeating the process AYT it means are you there it means this control character is used to determine if the remote machine is still up and running especially after long silence from the server it means after we are not getting any response from the server side then also if the program is there infinite loop it still it is processing it means then the user can use AYT control character that is are you there okay that can use this one then next one is EC that is arrays character when a user sends a data from the keyboard to the local machine they can use a delete or backspace button to delete the character the last character but type to do the same thing in the remote machine then we won't use any local button and then some special combination characters erect we have to use a telnet defines EC that is arrays character is EC is a command it can be used to arrays the character in the remote machine okay next EL arrays line arrays line this is used to arrays the current line in the remote host EC is an arrays character EL is an arrays line these and IAC one more is there that characters we how to use to modify the data change the data interrupt the program in a remote machine here example how to interrupt runway application program at the server side the user types control C in a local machine they can but in the telnet client sends the combination of IAC and IP to the server to interrupt the program in the remote machine this is a block diagram how we how to send and then how the client here client is there here the server is there here the server machine is there in infinite loop process then that time how the client can use if the infinite loop process is there in this one directly they can use control C and then if it is there in the server side how and what they have to use it means here the some control a special combination of characters some control characters we have to use through client we have to send IP through internet we have to send IAC IP is an internet protocol IAC is an interpret interpret as a control these characters we have to send to the server the server can interrupt by using these characters and then they can disconnect the infinite loop program in the receiver side interrupting the application program next one is out of band signaling to make control characters like EC EL IAC IP effective in special situation to make control characters more effective in special situation the telnet uses out of band signaling in this the control characters are preceded by IAC interpret as a control when a telnet process wants to send an out of band sequence of characters to the other process here client can send the data they can kept the data dm then data mark is an urgent pointer it can holds the address of the receiver side data IP and IAC they can discuss here and then if the process is not there in the infinite loop if it is there then we have to if it is not there it is automatically the current discards it means some special combination of characters we have to make more effective in special situation it means these characters IP and IAC if these two characters are not there we it is not possible to control the data for that these combination we have to make now a more effective in special situation ok this is our diagram that this is out of band signaling next think and write it can contain one question that is what is an escape character describe with an example now pause the video and answer the questions now answer for the above question it can have a many different functions it is used to send special instruction to printers and other devices connected to that particular system here here this is a first there are two diagrams are there firstly a control characters we have to send to the client the client can use some special characters that is IP and IAC to the server in the server by using these characters it can interpret it can disturb then they can get the whatever the output and then whatever the process they want they can get the final output in the application side or in the server side here if the program is there in finite loop in the client machine only there is no need to go to the server side and application side here only they can use some control characters that is control C and then some other combination of characters to break the or to interpret the program in the client side so interpreting the application program in this one by using these characters here directly they have interpreted are disturbed are interpreted in the client machine only that is b diagram interpreting the interrupting the client two different interpretations interruptions okay next mode of operations here we have to use three different modes are there first one is a default most telnet implementations operate in one of the three modes the default mode character mode and line mode these mode of operations we have to use in a telnet by default leaf they are not used anything it means by default we have to use that is default mode then character mode line mode what is the default mode okay when a user type a character and the client echoes the character on the screen but does not send it until whole line is completed in the default mode whatever the user is typing through keyboard all the data will echo or to the monitor on the monitor until the user can press the full enter button or full line that is default mode after sending the whole line to the server the server or client waits for GA that is go ahead after that command the data can goes to the server side and it can echoes to the monitor the server before accepting a new line from the user the operation is hop duplex it means in a hop duplex both sending process and receiving process can happen using different paths simultaneously but different path it is not efficient when TCP connection itself as a full duplex in TCP we are using it means it is an connection oriented protocol it is in full duplex it is not efficient in TCP but only it can operate in hop duplex part of the default mode okay next one is character mode TCP segments must send for each character of data first one there are three segments of the first one is user enters a character that is sent to the server second one is server acknowledges the issued character and echoes the character the third one is the client acknowledges the receipt of the echoed character in a default mode to show the concept and its deficiencies the client and server negotiate the terminal type and terminal speed and then server checks the login and password of the user here it can the two client and server they can communicate with each other what are the necessary materials we want here in this diagram it can can just go ahead will terminal type and do first the user can send the request after can get the acknowledgement then he can put the password after getting the password they can access the website or any user data line mode in a more in a new mode has been a new mode has been proposed to compensate for the deficiencies of difficult default mode and the character mode the line mode in line editing can echoes the character and then line arising and so on we have to use in a line mode only okay on the whole line to the server so the line mode looks like the default mode is not is there interfaces the user interface is responsible for translating the user friendly commands to the previous defined commands in a protocol two type commands are there that are open close display mode and then set status spend quit these are these can be used for different purpose in the user interfaces these are the references i have used to prepare the above ppt thank you