Question

Suppose Client X initiates a FTP session with Server W and requests data transferring. At about the same time, Client Y also initiates a FTP session with Server and requests data transferring W. Provide possible source and destination port numbers for:______.
a) The segments sent from X to W.
b) The segments sent from Y to W.
c) The segments sent from W to X.
d) The segments sent from W to Y.
e) Is it possible that the source port number in the segments from X to W is the same as that from Y to W?
f) How about if they are the same host? Hints: You may use any valid port numbers; make sure to use the correct patterns to design the port numbers to support communication

Answer 1

Answer:

Folllows are the solution to the given points:

Explanation:

In this question, the server uses special port 21 and  20 for the command and data transfer. A customer uses a random short-term N > 1023 and N+1 ports Listen and the Ports may be randomly distributed and the following samples are given for:  

In point (a):

X: 1030 Client, W server: 21 (service)  

W: 20 server (data) ,Client X:1031

In point (b):

Server W: 21 (command) Client Y: 1035  

Client Y: 1036, (data) Server W: 20  

In point (c):

Client X: 1030, Server W: 21.  

Client X: 1031, (data) Server W: 20  

In point (d):

Client X: 1035, Server W: 21.  

Client X: 1036 ,(data): Server W: 20.  

In point (e):

Yes, it's an opportunity. It can be the same as a certain likelihood.  

In point (f):

The port of the server is the norm. If W and Y are on the same host, the client's port numbers can vary.