Given a block diagram of an IP datagram as shown below to be sent from a...

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Given a block diagram of an IP datagram as shown below to be sent from a computer to a remote corporate network using a VPN: IP Datagram PPTP is used to implement a Layer 2 voluntary tunnel between the computer serviced by an ISP and the remote corporate network over the Internet. Shown below is a block diagram showing the format of the PPTP packet, where the labels A, B, C, D stand for headers and E stands for a protocol data unit, when it is being transmitted between the sending computer and the ISP network. A B D E (a) Write down what A, B, C, D and E exactly are. Describe one function of each of the protocols represented by labels C and D, respectively, using at most two sentences for each of the labels. (b) Write down two of the labels for the header or protocol data unit that will be left, if the VPN is a compulsory tunnel instead of a voluntary tunnel. An IDS consisting of all the IDS components as shown in Lecture No. 7-6, is used to monitor the network traffic on a network of IP address 192.168.1.0/24 and to protect a server of IP address 192.168.1.123 on the network. The IDS uses rule-based signature detection and has a rule to detect a signature string cmd.exe in packets. An attacker sends three packets to the server, with some of the packet details shown below: Packet Destination IP address 1 192.168.1.123 2 192.168.1.123 3 192.168.1.321 Containing cmd.exe command cmd.exe (a) Describe what will happen to the packets, respectively, when they go through the components: Sensor and Analyser, using at most two sentences for each packet. Note that a packet may not go through a component if it is dropped by the previous component. In this case, you may write down "NA". (b) Describe the overall action taken by the IDS on each of the packets, using at most one sentence for each of the packets. Given a block diagram of an IP datagram as shown below to be sent from a computer to a remote corporate network using a VPN: IP Datagram PPTP is used to implement a Layer 2 voluntary tunnel between the computer serviced by an ISP and the remote corporate network over the Internet. Shown below is a block diagram showing the format of the PPTP packet, where the labels A, B, C, D stand for headers and E stands for a protocol data unit, when it is being transmitted between the sending computer and the ISP network. A B D E (a) Write down what A, B, C, D and E exactly are. Describe one function of each of the protocols represented by labels C and D, respectively, using at most two sentences for each of the labels. (b) Write down two of the labels for the header or protocol data unit that will be left, if the VPN is a compulsory tunnel instead of a voluntary tunnel. An IDS consisting of all the IDS components as shown in Lecture No. 7-6, is used to monitor the network traffic on a network of IP address 192.168.1.0/24 and to protect a server of IP address 192.168.1.123 on the network. The IDS uses rule-based signature detection and has a rule to detect a signature string cmd.exe in packets. An attacker sends three packets to the server, with some of the packet details shown below: Packet Destination IP address 1 192.168.1.123 2 192.168.1.123 3 192.168.1.321 Containing cmd.exe command cmd.exe (a) Describe what will happen to the packets, respectively, when they go through the components: Sensor and Analyser, using at most two sentences for each packet. Note that a packet may not go through a component if it is dropped by the previous component. In this case, you may write down "NA". (b) Describe the overall action taken by the IDS on each of the packets, using at most one sentence for each of the packets.