CEH

Chapter 5: Scanning Networks 421

Chapter 5: Scanning Networks

1. A. Telnet is used to perform banner grabs against a system. However, other tools are avail-
   able to do this as well.


2. B. Netcraft is used to gather information about many aspects of a system, including operat-
   ing system, IP address, and even country of origin.


3. D. Nmap is a utility used to scan networks and systems and for other types of custom scans.


4. D. END is not a type of flag. Valid flags are ACK, FIN, SYN, and PSH.


5. A. Syn flags are seen only on TCP-based transmissions and not in UDP transmissions of
   any kind.


6. B. A NULL scan has no flags configured on its packets.


7. B. An ACK flag is part of the last part of the three-way handshake, and this part never hap-
   pens in a half-open scan.


8. B. An RST indicates that the port is closed.


9. B. An RST indicates the port is closed in many of the TCP scan types. The RST is sent in
   response to a connection request and the RST indicates that the port is not available.


10. A. The three-way handshake happens at the beginning of every TCP connection.


11. C. A three way handshake is part of every TCP connection and happens at the beginning of
    every connection. In the case of a half-open scan, however, a final ACK is not sent therefore
    leaving the connection halfway complete.


12. A. A three-way handshake is part of every TCP connection and happens at the beginning
    of every connection. It includes the sequence SYN, SYN-ACK, and ACK to be fully com-
    pleted.


13. A. An ICMP echo scan is a ping sweep type scan.


14. D. Vulnerability scans are designed to pick up weaknesses in a system. They are typically
    automated.


15. C. A proxy is used to hide the party launching a scan.


16. B. Tor is designed to hide the process of scanning as well as the origin of a scan. Addition-
    ally, it can provide encryption services to hide the traffic itself.


17. A. You do not need to use a proxy to perform scanning, but using one will hide the process
    of scanning and make it more difficult to monitor by the victim or other parties.


18. B. Vulnerability scanners are necessary for a security person to use in order to assist them
    in strengthening their systems by finding weaknesses before an attacker does.

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