This utility multiplexes a single TCP connection to multiple clients. The intended use is to allow multiple processes to connect to a single VESNA node, since hardware limitations prevent a node from serving more than one network client. In picture:
. +--------+
. -->| client |
. +-----------------+ / +--------+
. +-------+ | |-- +--------+
. | VESNA |----->| vesna_multiplex |----->| client |
. +-------+ | |-- +--------+
. +-----------------+ \ +--------+
. -->| client |
. +--------+
.
. <- west east ->The multiplexer makes as few assumptions as possible regarding the protocol used between the sensor node and clients.
For data received from the node and flowing east, the multiplexer makes byte-by-byte copies for each connected client. This means that, for example, periodic sensor reports will be received by all clients.
For data flowing east-to-west, multiplexer assumes that protocol is line oriented. It passes each complete line (n terminated) it receives from any client to the node. Typically, only one client will issue commands to the node at the time. It is up to the clients to synchronize their commands as necessary.
The multiplexer also recognizes some lines as commands for itself. Responses to those commands are sent back to the client that sent them and are not replicated to the node or other clients.
The sensor node has no capability to authenticate itself against the multiplexer, hence anyone on the network that knows multiplexer's IP and port can connect to it and impersonate the sensor node.
Similarly, since most clients expect to connect directly to the sensor node they have no concept of authentication. Anyone on the network that knows multiplexer's IP and port can connect and impersonate a client.
It is HIGHLY RECOMMENDED to only run the multiplexer on a secure network.
- ?ping
Responds with "ok". Can be used by clients to check whether a multiplexer is present on the connection.
- ?count east
Responds with the number of currently open eastward connections, followed by "ok". This is the number of connected clients.
- ?count west
Responds with the number of currently open westward connections, followed by "ok". This is the number of connected nodes (typically <= 1).
Run these commands:
python setup.py install
python setup.py testAfter installing, run the multiplexer with the following command:
vesna_multiplexBy default, multiplexer listens for eastward connections (clients) on port 2101 and for westward connections (node) on port 2102. Clients can connect only from localhost, while node can connect from any network interface. You can change these defaults with command line arguments. See --help.
The sensor node should be configured to "Automatically establish TCP connections" to the multiplexer's IP and port. Set to "Always connect and maintain connection" and select "Raw TCP" as service type. Also, it is recommended to disable "Raw TCP" under "Network Services".
The latest version is available on GitHub: https://github.com/avian2/vesna-multiplex
Copyright (C) 2014 SensorLab, Jozef Stefan Institute
Written by Tomaz Solc, <tomaz.solc@ijs.si>
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.