Iridium SBD Direct IP Server

This repository provides a server for testing Iridium SBD Direct IP messages. This server can be used with your official Iridium Direct IP server provider and also with the following Iridium SBD emulator.

This server includes a tiny Telegram bot to notify you about incoming MO (Mobile Originated) messages. See the following instructions to setup correctly your bot.

Cloning the repository

This repository depends on additional repositories which are included as GIT submodules, so when cloning use the flag --recursive to avoid some additional steps:

git clone https://github.com/lromeraj/isbd-server.git --recursive

If you have already cloned it without this flag, use the following command:

git submodule update --init

Building the server

This server depends on the NodeJS runtime environment (which you probably have already installed) but in case you don't, you can simply do:

NOTE: the following instructions assume you are working from Ubuntu. If you need specific instructions for your OS, search in Google how to install Node JS v14.x.

curl -sL https://deb.nodesource.com/setup_14.x -o nodesource_setup.sh

Check it's contents if you don't feel comfortable with a direct "blind" install:

nano nodesource_setup.sh

Finally install it:

sudo bash nodesource_setup.sh

If node and npm are accesible from your path, you are ready to build the server:

npm i

A file named .env should have appeared in the root of the repository, here you can specify your own configuration, like your bot token, secrets ... see the environment variables section.

Environment variables

Variable	Description	Default
MO_TCP_HOST	Address where the server should accept incoming connections	0.0.0.0
MO_TCP_PORT	Port where the server will listen for incoming TCP packets	10801
MO_TCP_CONN	Maximum connections to be processed simultaneously	64
MO_TCP_QUEUE	Maximum size of the TCP queue	32
MO_MSG_DIR	Directory where the incoming MO messages will be stored. Relative to the process working directory	mo/
TELE_BOT_TOKEN	Telegram bot access token	n/a
TELE_BOT_SECRET	Telegram bot secret used during handshake	n/a

Running the server

After building the server, you should see a valid symlink in the root of the directory pointing to some script inside the build/ directory, use the following command to see some command line options of the server:

node server.js --help

This should output something like:

Usage: server [options]

A simple Iridium SBD vendor server application

Options:
  -V, --version            output the version number
  -v, --verbose            Verbosity level
  --mo-tcp-port <number>   MO TCP server port
  --mo-tcp-host <string>   MO TCP server host
  --mo-tcp-conn <number>   MO TCP maximum concurrent connections
  --mo-tcp-queue <number>  MO TCP queue length
  --mo-msg-dir <string>    MO message directory
  -h, --help               display help for command

To execute the server using a background process manager use:

npm run start

To stop it:

npm run stop

Use the following command to see background processes:

npx pm2 list

Take a look to the following URL in order to see more command line options of this process manager.

NOTE: environment variables are useful for demonized processes, but if you want to execute the server without a process manager and just test it, you can use the inline command options which will override the settings specified in the environment file.

Server functioning

The server will start listening on the port specified in the MO_TCP_PORT environment variable. For each socket connection the server follows the following logic:

1. A file will be created with the following naming convention: RAW_<IID>.bin inside the specified MO_MSG_DIR directory.
2. A watchdog timeout is created in order to limit the maximum time a connection can be opened in order to limit resources used.
3. All data sent from the socket will be written to a new file with a maximum fixed limit of 1024 bytes.
   • If this limit is exceded, the connection will be destroyed and the file will be removed.
4. If the received data is within the limits, the connection will be gracefully closed.
5. A task will be created to analyze the file contents, if the file has a valid MO message it will be permanently stored inside the MO_MSG_DIR and renamed using the following naming convention: <IMEI>_<MOMSN>.sbd, otherwise the file will be removed.

Reverse proxy

If you are going to expose this server to a WAN, it is recommended to use a reverse proxy in order to increase security, in this case we are using HAProxy with the following configuration:

frontend isbd
  bind *:9000
  mode tcp
  acl white_list src 12.47.179.11
  tcp-request connection reject if !white_list
  use_backend iridium-sbd-server

backend iridium-sbd-server
  mode tcp
  timeout server 5s
  timeout connect 5s
  server isbd localhost:10801

This checks if the address which requested TCP handshake is whitelisted. In this case the whitelisted IPv4 corresponds to the official Iridium SBD Direct IP server.

Tools

IMPORTANT: the tools have been removed after including the Iridium SBD emulator as a submodule which already includes all of this tools natively, please see the official Iridium SBD emulator repository.