Question: Suppose a firewall is configured to allow outbound TCP connections but inbound connections only to specified ports. The FTP protocol now presents a problem: when

Suppose 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.

Step by Step Solution

★★★★★

3.44 Rating (160 Votes )

There are 3 Steps involved in it

1 Expert Approved Answer

Step: 1 Unlock

a FTP Protocol and PORT Command FTP or File Transfer Protocol operates by establishing two connections between the client and server the control conne... View full answer

Question Has Been Solved by an Expert!

Get step-by-step solutions from verified subject matter experts

Step: 2 Unlock

Step: 3 Unlock

Students Have Also Explored These Related Computer Networking Questions!

Planning is one of the most important management functions in any business. A front office managers first step in planning should involve determine the departments goals. Planning also includes...

Managing Scope Changes Case Study Scope changes on a project can occur regardless of how well the project is planned or executed. Scope changes can be the result of something that was omitted during...

Read the case study "Southwest Airlines," found in Part 2 of your textbook. Review the "Guide to Case Analysis" found on pp. CA1 - CA11 of your textbook. (This guide follows the last case in the...

This assignment gives you the opportunity to examine a real software requirements specification. This will give you the chance to become more familiar with the different elements in an SRS. For this...

1.Review the attached software requirements specification document. 2. In a separate document, identify two positive aspects of this SRS document. Justify your answer by specifying what you find...

Chapter 5 2. Consider a simple UDP-based protocol for requesting files (based somewhat loosely on the Trivial File Transport Protocol, or TFTP). The client sends an initial file request, and the...

I have to create a program in C and I can't figure it out. The program has to read a source file. Please help. /******************************************************************** PROJECT: Glossary...

There are two problems due this week (each worth 35 points) as follows. Case 5-1David L. Miller: Portrait of a White-Collar Criminal (page 144). In comprehensive paragraphs, answerrequirements 1?6....

Installing the Windows Firewall In this section, we will examine the current Firewall configuration. Then, we will reconfigure the Windows Firewall and change it into a VPN server. After the VPN...

The Saunders Investment Bank has the following financing outstanding. What is the WACC for the company? Debt: 60,000 bonds with a coupon rate of 6 percent and a current price quote of 109.5; the...

The hourly temperatures (in degrees Fahrenheit) at Eppley Airfield Airport in Omaha, Nebraska, in May 2014 are de- scribed by the density histogram in Fig. 87. The heights of the bars were drawn...

Question 2 8 pts Assume today's settlement price on a Chicago Mercantile Exchange ( CME ) GBP futures contract is $ 1 . 2 9 0 0 / EUR . You have a long position in one contract. The contractual size...

What is the position of the transmission media in the OSI or the Internet model?

Which of the four digital-to-analog conversion techniques (ASK, FSK, PSK or QAM) is the most susceptible to noise? Defend your answer.

We have a baseband channel with a 1-MHz bandwidth. What is the data rate for this channel if we use each of the following line coding schemes? a. NRZ-L b. Manchester c. MLT-3 d. 2B1Q

A flexible budget variance for a manufacturing cost is computed as the difference between Select one: A. flexible budget costs and original budget costs. B. flexible budget costs and static budget...

1. ___ is equal to __ net fixed assets minus __ net fixed assets plus . An expense that lowers net income but does not affect a firm's cash flow is referred to as a(n) ___ item.

Use a query to show the invoices and invoice totals in Figure P7.17 . Sort the results by customer code and then by invoice number.