 Hello everyone, welcome to the session on Secure Cell Learning Outcome. At the end of the session, students will be able to describe the concept of Secure Cell that is SSH, content, versions, components, SSH transport layer protocol and SSH authentication protocol, authentication, SSH connection protocol, SSH applications and forwarding. Last one is format of the SSH packet. These are the points I am going to cover in this video about Secure Cell. SSH is in one of the most secure application protocol reduced to send the data. When another popular row as compared to the remote login, Secure Cell can provide the more security than the telnet. As this when another popular remote login application protocol is in Secure Cell, SSH is more secure and provide more services than the telnet. What is telnet? Telnet is a terminal network. Already we have discussed about the telnet. In the last two videos, a telnet can be used for different purpose while sending the data from local machine to the remote machine. There are two urgins are there that are SSH 1 and SSH 2. SSH is a proposed application layer protocol with four components here and the SSH can contains four components. What are those components? That is a transport layer only TCP is there in the application layer, SSH transport layer protocol, authentication, connection and application. These are the four components can be used in a Secure Cell. Let us see one by one in detail about the components of SSH. First one is SSH transport layer. SSH transport layer protocol is a new layer is an independent protocol referred to as a SSH transport. In this one while transmitting the data it is an independent of the upper layer and lower layer. Directly it can transfer the data without any need or help of other protocol. List them service provided by this protocol is an provisional confidentiality of the message exchange. Second is data integrity. It is guaranteed that the message exchange between the client and server do not change by any another user or introducer. In which means while transmitting the data from client to the server the data is securely or confidently the data can reach to the destination. It can provide the more security than the telnet and other protocol. It is not possible to change any some other third party in this one. Server authentication the client is sure that the server is the one that can claims the data is issued from the client. Compression of the message that improves the efficiency. It means while sending the huge amount of data or large amount of data we have to compress the data. It means that compressing the data can improve the efficiency of data. It means the data can reach to the destination within a short time. Make it more difficult. SSH authentication protocol after secure channel is established between the client and server we have to go to the transmission of the data that is SSH can call another software that and that can authentication authenticate the client for the server. It means after authentication the user can go to the transmitting the data from client to the server that is SSH connection protocol after the secure channel is established and both server and client are authenticated for each other. It means both the client after connection is established that the server and client can identify with each other and they can discuss with each other because both the client and server are the authorized user for that particular connection. And then they can go to the SSH can call a piece of piece of software that implement the third protocol that is SSH connection. One of the service provided by the SSH connection protocol agent do multiplexing SSH can take the secure channel established by the two previous protocol and lets the client creates multiple logical channels over it. It means after establishing the connection they can go to the data transfer page in the data transfer page both the users can both the users I mean client and server they can authorize users for that particular network then they can easily transfer the data and issue the data without any problem both the users can independently consent the data and issue the data and it can provide the more security in the it can get the more security in the SSH. Think and write it can contains one question that is what is SSH and list some applications of SSH. Now pause the video and answer the above question think and write definition it is a cryptographic network protocol for operating network services securely over an un-secured network a cryptographic network protocol for operating network services securely over an un-secured network SSH application remote login is one of the services that can use the SSH connection protocol. File transfer application can use one of the logical channels for this purpose and then SSH can be used for secure file transfer telnet and smtp automated and secure file transfer okay here some applications are here we have to use a remote login concept here and then file transfer application can be used to logical channel for this purpose and then here we have to use a telnet and smtp that is terminal network and simple mail network transfer protocol for transmitting the data here from one user to the another user automated and secure file transfer means here automatically we have to send by using without any problem and then it can provide a secure data transfer to the next user. Secure management of network infrastructure components port forwarding one of the interesting services provided by the SSH protocol is to provide port forwarding here we can use a secured channel available in SSH to access an application protocol that does not provide security services SSH port forwarding mechanism creates and tunnel the message belonging to other protocol can travel this mechanism sometimes referred to as SSH tunneling it means what is SSH tunneling how we have to transfer the data here it can contains one diagram that is a telnet client SSH client and then secure connection and then here here this is a block diagram of port forwarding how we have to the telnet client can get the data and then can go to the SSH client that is secure shell client and then here they can use the data and they can transfer that data the forward the port they can forward this data through this tunnel that is a secure connection this is the both this is another tunnel can be used between the SSH client and SSH server they can transfer the data without any problem it means here the this is a client machine or local site they can prepare the data they through this tunnel they can transfer to the remote login users that is port forwarding format of the SSH packet this can contain different field that are length padding type data and CRC length is a four bytes and padding is in one to eight bytes and then type is in one bytes data actually that depends upon the user and type of protocol used by the user that is where size is variable that is not fixed okay and then CRC is in four bytes encrypted for confidentiality SSH packet format now in brief discussion about the each fields of SSH packets okay first one is a length it can defines four byte field including the what type of data we are sending what is that data and CRC field but not the padding and the length of the field what type of data and then CRC also we have to use CRC can be used to find the errors while transmitting the data padding it is an one to it can defines one to eight bytes of padding is added to the packet to make the attack on security provision more difficult okay next one is type it can defines type can defines a one byte field defines a type of packet used by the SSH protocol it means what type of protocol we have to use it can defines okay data this field is of variable length field and then I said in the diagram that depends upon the user and what type of protocol they are using that depends upon type of protocol we are using that length of that field is variable okay CRC CRC is in cyclic redundancy check this field is used for error detection and error correction here the overall concept we how to use in a secure shell in a overall description about the secure shell is in while transmitting the data from one user to another user by using different protocol previously previous video we have discussed about the telnet and the some other protocol as compared to telnet and TCP UDP SSH can provide the more secure than telnet okay that as a name itself indicates that the secure shell it means SHH it means secure shell this can be used for transmitting the data references these are the two references I have used for preparing the above ppt thank you