Server implementation (using Paramiko) for sftp AND command execution

Question

the server implementation for sftp works well but now I want to use it additional for command execution from clients

the code works well as a sftp Server but I have no glue how to extend it for command execution...

using: set_subsystem_handler is using sftp, using commands failed...

ideas?

working example: sftp -P 3376 -i key.file user1@localhost

failed example: ssh -p 3376 -i key.file user1@localhost ls

class StubServer (ServerInterface, ):
    def check_auth_publickey(self, username, key):
            return paramiko.AUTH_SUCCESSFUL

    def check_channel_request(self, kind, chanid):
        return OPEN_SUCCEEDED

    def get_allowed_auths(self, username):
        return "publickey"

    def check_channel_exec_request ( self, channel, command ):
        print ( f'....> check_channel_exec_request commmand: {command}' )
        return True 

class ConnHandlerThd(threading.Thread):
    def __init__(self, conn, addr, serverkeyfile ):
        threading.Thread.__init__(self)
        self._conn = conn
        self._addr = addr
        self._serverkeyfile = serverkeyfile

    def run(self):
        server_key = paramiko.RSAKey.from_private_key_file(self._serverkeyfile)
        name = server_key.get_name()

        transport = paramiko.Transport(self._conn)
        transport.add_server_key(server_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, serverkeyfile, logfile=logfile, level=level, backlog=backlog ):
    paramiko_level = getattr(paramiko.common, level)
    paramiko.common.logging.basicConfig(level=paramiko_level)

    paramiko.util.log_to_file ( logfile, level = 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, addr, serverkeyfile )
        srv_thd.setDaemon(True)
        srv_thd.start()

start_server(host=host, port=port, serverkeyfile=keyfile, level=level, logfile=logfile, backlog=backlog)

Martin Prikryl · Accepted Answer · 2020-06-08 18:12:24Z

1

The ssh ... command uses exec SSH channel, not sftp.

So you need to handle the exec channel too.

answered Jun 8, 2020 at 18:12

Martin Prikryl

205k64 gold badges561 silver badges1.1k bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Server implementation (using Paramiko) for sftp AND command execution

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related