What is the Difference Between Active and Passive FTP?
For a protocol with nearly fifty years on the clock, FTP can sometimes be a lot more complicated than most would assume. In particular, there is often a strong misunderstanding of the differences between active and passive FTP sessions, which can lead to confusion around port numbers in use and how the protocol really works. So what are the differences between active and passive FTP; and what are the advantages and disadvantages of using either mode?