FTP Client via Telnet

redneon · 10-17-2004, 06:56 AM

I'm trying to write a simple frontend to an FTP site that I use. Not an fully fledged client. To do this I've captured a standard FTP stream using Ethereal which looks like this (the lines in red are the lines sent from my machine and the lines in black are the lines from the server)...

Code:

220 FTP server () ready.
USER user
331 Password required for user.
PASS password
230 User user logged in.
PORT 82,76,233,125,12,125
200 PORT command successful.
NLST
150 ASCII data connection for /bin/ls (82.76.233.125,3197) (0 bytes).
226 ASCII Transfer complete.
QUIT
221 Goodbye.

If I try to replicate this telnet to the server on port 21 when I run the NLST command it doesn't actually output a list. How can I get this output? It just seems to hang when I run NLST. Not even QUIT works afterwards. I've read through the RFC but I can't find anything useful.

Cheers,

Darrell

david_ross · 10-17-2004, 07:29 AM

Ftp sessions actually consist of 2 connections, one for data and one for commands. You need to use PASV ftp if you want to connect to the server to receive the data rather than have the server connect to you.

redneon · 10-17-2004, 11:04 AM

So if I wanted to telnet to an FTP server what would I do? I've just tried opening two telnet connections to an FTP server and done this...

telnet 1
USER user
PASS pass

telnet 2
USER user
PASS pass
PASV

telnet 1
NLS

I thought this may display the result from the NLS on telnet 2 using the PASV mode you mentioned.

Darrell

itsme86 · 10-17-2004, 11:07 AM

This should be everything you need regarding FTP sessions:

http://war.jgaa.com/ftp/?cmd=rfc