Hello all,

I'm studying socket programming and have trouble when simulate a FTP server (I don't want to use pyftpdlib). The problem is when the client want to list the directory (LIST command) on the server, I do not find a way to send directory contents.

here is the code:

#!/usr/bin/python

from socket import *

host = "0.0.0.0"
port = 21

s = socket(AF_INET, SOCK_STREAM)
s.bind((host, port))
s.listen(1)

print "[+] Simple FTP Server Started."
print "[+] Listening on port %d ..." % port

cl, addr = s.accept()

print "- Connection accepted from %s" % addr[0]

def ftpserv():
	dirlist = "drwxrwxrwx    1 100      0           11111 Jun 11 21:10 file1.txt\r\n"
	dirlist += "-rw-rw-r--    1 1176     1176         1060 Aug 16 22:22 file2.txt\r\n"
	
	welcome = "220 Welcome to Simple FTP Server\r\n"
	cl.send(welcome)
	cl.recv(1024)
	cl.send("331 User name okay, need password\r\n")	# received USER
	cl.recv(1024)
	cl.send("230-Password accepted\r\n")		# received PASS
	cl.send("230 User logged in.\r\n")
	cl.recv(1024)
	cl.send("215 UNIX Type: L8\r\n")   # received from SYST
	cl.recv(1024)
	cl.send("211-Features:\r\n")		# received from FEAT
	cl.send("211 End\r\n")
	cl.recv(1024)
	cl.send("200 Type set to I\r\n")	# received from TYPE I
	cl.recv(1024)
	cl.send("200 OK\r\n")			# received from REST 0
	cl.recv(1024)
	cl.send("257 \"/\" is current directory\r\n")	# received from PWD
	cl.recv(1024)
	cl.send("227 Entering Passive Mode ("+addr[0]+",2521)\r\n")	
	cl.recv(1024)
	cl.send("150 Here comes the directory listing\r\n") 	# received from LIST
	cl.send("total 2\r\n"+dirlist)
	cl.send("226 Directory send ok\r\n")
	cl.close() 
ftpserv()

s.close()

thanks for the help :)

Edited 5 Years Ago by l00kit: n/a

I do not understand how you process information. For me looks that you do not process or save received information.

I do not understand how you process information. For me looks that you do not process or save received information.

I do not process the information, I just simulate it to check that the FTP client will work well. The problem is when the FTP client send the LIST command to the server (actually, the script above).

what do you mean by list command?
Normally, ftp client will read the data of the connected address in a list form.... is that what you want?

what do you mean by list command?
Normally, ftp client will read the data of the connected address in a list form.... is that what you want?

Ok, actually, what I want to build is a proof of concept. I research vulnerability on a ftp client, and the client error (buffer overflow condition) when received LIST with long string (e.g. A * 5000). But I can't simulate it, and got stuck on handle LIST from client.

The error occured when this condition is met:

junk = A * 5000
dirlist = "drwxrwxrwx 1 100 0 11111 Jun 11 21:10 "+junk+".txt\r\n"
cl.send("total 2\r\n"+dirlist)


please help. thank you.

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