A+ Guide To It Technical Support
10th Edition
ISBN: 9780357108291
Author: ANDREWS, Jean.
Publisher: Cengage,
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Chapter 8, Problem 3TC
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Given:
A server is running both a Telnet server and an FTPS server.
To find: The reason that the telnet server is not recommended for using a remote computer...
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A hacker just set up a TCP connection with a web server in Chicago, Illinois, claiming he is coming in with a source IP address that clearly belongs to a network in Copenhagen, Denmark. In examining the session logs, you notice that he was able to complete the three- way handshake for this connection in 10 milliseconds. How can you use this information to prove he is lying?
The first of these packets is from your computer to the DHCP server telling it to release the lease on your IP address. The next 4 packets renew that lease. Note that the source address on the “DHCP Discover” and “DHCP Request” packets is 0.0.0.0. This indicates that your computer does not actually use its new IP address until the interchange has completed. Also note that the destination address in each of the 4 packets is a broadcast address[1]. It should be obvious to you why the first two packets are broadcasted, but what about the last two? Can you explain this? Answer the questions in your Word document right after you post a snapshot of the DHCP packet screen. (#4)
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?
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- In class, we have talked about how messages are transferred from one layer to another on our TCP/IP model and the different protocol data Units (PDUs). You are now required to use Wireshark to perform network analyses covering the following : 1.Capture network packet on a LAN 2.Perform network sniffing on the LAN (e.g.)Sniffing Usernames, Passwords, Web Pages, etc 3.Use Wireshark to examine frames after the attack.arrow_forwardA person wishes to sniff the packets going to the outside world from your LAN. How is he going to check the information passing out or your network without letting the host or anyone in thenetwork know?What if it is a switched LAN or a broadcast LAN?A potential security threat with all the TCP based network services is that anyone can remotely conduct experiments to know whether a particular service is available. for instance, is an attempt to connect certain port on specific machine (say M) any remote user can check if M is running an SMTP server on port 25. Under this scenario it becomes easy to find machines that aresusceptible to send mail bugs. In order to combat such a potential threat, can you come up with a method through which only authorized users (who possess a certain secret) will be able to getresponse to a TCP SYN packet?elaborate your method with the help of an example.Give a step by step description of both the scenarios.arrow_forwardWhich of the following statements are true about MAC protocols? A. Medium Access Control protocols determine the sequence in which end hosts get to send packets over a shared medium, such as a radio channel or shared cable. B. ALOHA is a simple, deterministic access protocol in which each end host with data to send transmits in strict round robin order. C. In an ALOHA network, the end hosts can spend a large fraction of their time sending packets that will collide with others. D. Random access protocols are generally more complicated and less reliable than deterministic access protocols. You are considering two retransmission strategies for all hosts in a network using the ALOHA protocol. The first is a deterministic strategy where the first time a collision is detected, the sender waits one second and retransmits. The second time a collision is detected, the sender waits two seconds and retransmits, and so on. The second strategy is a random strategy where when a collision is…arrow_forward
- 15. For the Wireshark trace below, answer the following questions, indicating where in the message you find the answers: a. b. What time did the server respond? When was the document last modified? C. How many bytes are in the document being returned? d. Did the server agree to a persistent connection? Hypertext Transfer Protocol HTTP/1.1 200 OK\r\n Date: Wed, 05 sep 2012 03:04:30 GMT\r\n Server: Apache/2.2.3 (centos)\r\n Last-Modified: wed, 05 sep 2012 03:04:01 GMT\r\n\ ETag: "d6c97-1194-a069ca40"\r\n\ Accept-Ranges: bytes\r\n + Content-Length: 4500\r\n\ Keep-Alive: timeout=10, max=100\r\n] Connection: Keep-Alive\r\n\ Content-Type: text/html; charset=UTF-8\r\n \r\n\ + Line-based text data: text/htmlarrow_forwardSuppose a firewall is configured to allow outbound TCP connections but inbound connections only to specified ports. The FTP protocol now presents a problem: When an inside client contacts an outside server, the outbound TCP control connection can be opened normally but the TCP data connection traditionally is inbound. (a) Look up the FTP protocol in, for example, Request for Comments 959. Find out how the PORT command works. Discuss how the client might be written so as to limit the number of ports to which the firewall must grant inbound access. Can the number of such ports be limited to one? (b) Find out how the FTP PASV command can be used to solve this firewall problem.arrow_forwardThe 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 dcabefarrow_forward
- When the FTP client is connected to the FTP server, the Transport Layer protocol TCP created a reliable session. TCP is routinely used during a session to control datagram delivery, verify datagram arrival, and manage window size. For each exchange of data between the FTP client and FTP server, a new TCP session is started as shown in this WireShark screenshot: 1.Identify Three-way handshake packets and write them here? 2.Identify and list the graceful termination of communication between FTP client and server? 3. what is the port number of FTP protocol? 4. Identify the source and distention IP addresses?arrow_forwardDraw a NAT Table Entry at the Router for the Computer (A) (shown with a smiley face J) trying to reach the Web Server (listening at Port 80) as shown. You may use dynamic port numbers.arrow_forwardby using ubuntu you Must to send and receive packets between two computers ( write program by using C langug ) but this program MUST be inclod authentication & confidentiality services are deployed using relevant protocols at different layers, for instance TLS, SSL or IPSec. than use Wireshark to display the protocols if it work when you Make transmit packets for examples: use matching user name & password for authentication use hashing to provid confidentialityarrow_forward
- In IPsec, each incoming and outgoing packet will be checked with the Security Policy Database (SPD) and the Security Association Database (SAD). (a) What is the checking done with the SPD: (b) What is the checking done with the SAD? (c) Each security association stored in SAD is identified by an integer. What is this integer called?arrow_forwardIn order to implement a DNS amplification attack, the attacker must trigger the creation of a sufficiently large volume of DNS response packets from the intermediary to exceed the capacity of the link to the target organization. Consider an attack where the DNS response packets are 500 bytes in size (ignoring framing overhead). a. How many of these packets per second must the attacker trigger to flood a target organization using a 30-Mbps link? A 100-Mbps link? Or a 1-Gbps link? b. If the DNS request packet to the intermediary is 60 bytes in size, how much bandwidth does the attacker consume to send the necessary rate of DNS request packets for each of these three cases?arrow_forwardThe packets listed below were received by your network's stateful firewall, and they are shown in the following table in random order. The IP addresses of two hosts in your LAN, IP1 and IP2, and two external hosts, IP3 and IP4, are assumed to be IP1 and IP2, respectively. Indicate the number of established sessions and the number of half-formed sessions by evaluating these packets. established sessions. Packet Direction Pa1 Pa2 Pa3 Pa4 Pa5 раб Pa7 Pa8 Pa9 out Out in Out In in out out In Source IP IP1 IP2 IP3 IP2 IP4 IP4 IP2 IP1 IP4 Dest. IP IP3 IP4 IP1 IP4 O None of them IP2 IP2 IP4 IP3 IP2 Source Dest. Port Port 23 X 25 23 25 y y 80 X n y X y 25 25 n 23 80 SYN 1 1 1 0 1 0 1 0 1 ACK 0 1 1 1 0 1 1 1 0 O The number of established sessions=2 & The number of half established sessions = 1 The number of established sessions=0 & The number of half established sessions - 3 O The number of established sessions 2 & The number of half established sessions = 2 O The number of established…arrow_forward
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