multithreaded sftp server in python based on https://github.com/rspivak/sftpserver

sftpserver_main.py

import time
import socket
import optparse
import sys
import textwrap

import paramiko

from sftpserver.stub_sftp import StubServer, StubSFTPServer

import threading

HOST, PORT = 'localhost', 3373
BACKLOG = 10


class ConnHandlerThd(threading.Thread):
    def __init__(self, conn, keyfile):
        threading.Thread.__init__(self)
        self._conn = conn
        self._keyfile = keyfile

    def run(self):
        host_key = paramiko.RSAKey.from_private_key_file(self._keyfile)
        transport = paramiko.Transport(self._conn)
        transport.add_server_key(host_key)
        transport.set_subsystem_handler(
            'sftp', paramiko.SFTPServer, StubSFTPServer)

        server = StubServer()
        transport.start_server(server=server)

        channel = transport.accept()
        while transport.is_active():
            time.sleep(1)


def start_server(host, port, keyfile, level):
    paramiko_level = getattr(paramiko.common, level)
    paramiko.common.logging.basicConfig(level=paramiko_level)

    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
    server_socket.bind((host, port))
    server_socket.listen(BACKLOG)

    while True:
        conn, addr = server_socket.accept()

        srv_thd = ConnHandlerThd(conn, keyfile)
        srv_thd.setDaemon(True)
        srv_thd.start()


def main():
    usage = """\
    usage: sftpserver [options]
    -k/--keyfile should be specified
    """
    parser = optparse.OptionParser(usage=textwrap.dedent(usage))
    parser.add_option(
        '--host', dest='host', default=HOST,
        help='listen on HOST [default: %default]')
    parser.add_option(
        '-p', '--port', dest='port', type='int', default=PORT,
        help='listen on PORT [default: %default]'
        )
    parser.add_option(
        '-l', '--level', dest='level', default='INFO',
        help='Debug level: WARNING, INFO, DEBUG [default: %default]'
        )
    parser.add_option(
        '-k', '--keyfile', dest='keyfile', metavar='FILE',
        help='Path to private key, for example /tmp/test_rsa.key'
        )

    options, args = parser.parse_args()

    if options.keyfile is None:
        parser.print_help()
        sys.exit(-1)

    start_server(options.host, options.port, options.keyfile, options.level)

if __name__ == '__main__':
    main()

Before using it please make sure the connection is actually authenticated against the configured key. I have not used this code for a while but remember a case when it was letting everyone in :)

Use at your own risk.

yes, as you said, it's letting anybody in. Can it be set to authenticate with the key? If you have time, can you do it? Thanks