You wish to make use of “port knocking” technologies. How can you BEST explain this?
A.
Port knocking is where the client will attempt to connect to a predefined set of ports to identify him as an
authorized client.
B.
Port knocking is where the user calls the server operator to have him start the service he wants to connect
to.
C.
This is where all the ports are open on the server and the connecting client scans the open port to which he
wants to connect to see if it’s open and running.
D.
Port knocking is where the port sequence is encrypted with 3DES and only the server has the other key to
decrypt the port sequence.
Explanation:
Port knocking is an authentication method used by network administrators to control access to computers or
other network devices behind a firewall. Port knocking takes advantage of firewall rules to allow a client who
knows the “secret knock” to enter the network through a particular port by performing a sequence of connection
attempts (called a knock sequence). The correct knock sequence for any given port is created for specific IP
addresses by the network administrator. A small program called a daemon monitors the firewall log files for
connection requests and determines whether or not a client seeking the network is on the list of approved IP
addresses and has performed the correct knock sequence. If the answer is yes, it opens the associated port
and allows access. Of course, if unauthorized personnel discover the knock sequence, then they, too, can gain
access.
Incorrect Answers:
B: Port knocking is not where the user calls the server operator to have him start the service he wants to
connect to.
C: Port knocking is not where all the ports are open on the server and the connecting client scans the open port
to which he wants to connect to see if it’s open and running.D: Port knocking is not where the port sequence is encrypted with 3DES and only the server has the other key
to decrypt the port sequence.http://whatis.techtarget.com/definition/port-knocking
http://www.portknocking.org/