The Book of PF, 2nd Edition

That Sad Old FTP Thing

The short list of real-life TCP ports we looked at a few moments back contained, among other things, FTP, the classic file transfer protocol. FTP is a relic of the early Internet, when experiments were the norm, and security was not really on the horizon in any modern sense. FTP actually predates TCP/IP,^[17] and it is possible to track the protocol’s development through more than 50 RFCs. After more than 30 years, FTP is both a sad old thing and a problem child—emphatically so for anyone trying to combine FTP and firewalls. FTP is an old and weird protocol, with a lot to dislike. Here are the most common points against it:

• Passwords are transferred in the clear.

• The protocol demands the use of at least two TCP connections ...