问题
When I entered passive mode in FTP, I have got:
227 Entering Passive Mode (213,180,204,183,230,205).
First 4 numbers are the IP addresses, but what are the two last?
Are they two ports?
回答1:
the last two are: p1 and p2 from RFC of ftp: http://www.faqs.org/rfcs/rfc959.html
to get port, use:
p1 * 256 + p2, then connect to this port
回答2:
the port number is a 16-bit value between 0 and 65535 due to some constraints the authors have decided that all numbers between commas should be 8-bit (between 0 and 255). Thus, the 16-bit port number is represented with 2 8-bit numbers.
In your case the port number will be 230 * 256 + 205 = 59085
来源：https://stackoverflow.com/questions/9966993/how-to-get-port-in-ftp-protocol-from-passive-mode