Suppose you want your firewall to block all incoming Telnet connections but to allow outbound Telnet connections. One approach would be to block all inbound packets to the designated Telnet port (23). (a) We might want to block inbound packets to other ports as well, but what inbound TCP connections must be permitted in order not to interfere with outbound Telnet? (b) Now suppose your firewall is allowed to use the TCP header Flags bits in addition to the port numbers. Explain how you can achieve the desired Telnet effect here while at the same time allowing no inbound TCP connections.

Suppose you want your firewall to block all incoming Telnet connections but to allow outbound Telnet connections. One approach would be to block all inbound packets to the designated Telnet port (23). (a) We might want to block inbound packets to other ports as well, but what inbound TCP connections must be permitted in order not to interfere with outbound Telnet? (b) Now suppose your firewall is allowed to use the TCP header Flags bits in addition to the port numbers. Explain how you can achieve the desired Telnet effect here while at the same time allowing no inbound TCP connections.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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b) TCP demultiplexing. Suppose a process in host C has a TCP socket with port number 787. Suppose host A and host B each send a TCP segment to host C with destination port number 787. Will both of these segments be directed to the same socket at host C? If not, how will the process at host C know that these segments originated from two different hosts?
The following gives some facts about Evasion attack (refer to the following figure which shows the attacking scenario for the facts). Please select the correct order to make this attack work. a. Packet "R" is buffered; b. Packet "EWT" is sent and accepted by NIDS; c. Finish three-way handshake to establish a TCP connection to the destination; d. Packet SYN carrying data "R" is sent; e. Packet "EWT" is accepted by the destination; f. Packet "R" and "EWT" are assembled at the destination . Question 11 options: dabcef dacbef dbacef dcabef
This a TCP question, given the context of question 11 please answer and show work for question 12
Describe a common scenario that involves two different computing machines transmitting a video file over an unprotected ftp connection. The TCP three-way handshake should be considered a potential weak point in this scenario.
Suppose a TCP Vegas connection measures the RTT of its first packet and sets BaseRTT to that, but then a network link failure occurs and all subsequent traffic is routed via an alternative path with twice the RTT. How will TCP Vegas respond? What will happen to the value of Congestion Window? Assume no actual timeouts occur, and that 3 is much smaller than the initial Expected Rate.
Datagram Congestion Control Protocol (DCCP) is a connection-oriented protocol which works as a mechanism for detecting congestion. It provides unreliable flow of datagrams and reliable handshake for connection setup and teardown.Based on the description given above, ELABORATE your answer from the questions below:a) EXPLAIN any FIVE (5) differences of DCCP from Transmission Control Protocol (TCP).b) DESCRIBE the TWO (2) congestion control mechanisms supported by DCCP.
Suppose that MSS = 2000 bytes, TCP is in AIMD, and its window size is currently W = 4. Assume the slow start threshold is infinity. a) After receiving 4 non-duplicate ACKs, what is TCP’s window size? Explain your result by showing the relevant formulas. b) After these 4 ACKs, packet loss is detected through a timeout. What is TCP’s window in bytes immediately after the loss? What is the slow start threshold in bytes? c) Specify the window size for each of the five RTTs (one value of W per RTT) following the loss in part b. No additional packet loss occurs.
b. Suppose that you are hired by a local company to set up a router that both serves as the network's bidirectional firewall and also NATS hosts in the corporate network. The corporate network consists of about 100,000 machines that simultaneously access the Internet using port-based NAT. What problem could arise if the corporate network only has a single public IP address?
The following event is shown to occur in the figure below illustrating the operation of TCP Reno. For the following prompt, clearly state where it occurs and how we can identify where this event occurs based on the shape of the graph or changes to the congestion window size. a.) TCP congestion avoidance.
True or False 1. In 802.11 CSMA/CA, when a station senses the medium to be idle it sends a frame immediately 2. TCP utilizes a single retransmission time-out mechanism. The RTO is picked at the start of the TCP session and remains fixed for the duration of the session. 3. TCP segments can only be lost when router queues overflow. Please explain if possible，Thank you!!
If host A receives two SYN packets from the same port from remote host B, the second may be either a retransmission of the original or, if B has crashed and rebooted, an entirely new connection request. (a) Describe the difference as seen by host A between these two cases. (b) Give an algorithmic description of what the TCP layer needs to do upon receiving a SYN packet. Consider the duplicate/ new cases above and the possibility that nothing is listening to the destination port.