prochost (process host)

A service for allowing remote access via SSH to the input/output of a process, using a pseudoterminal (PTY).

Intended to allow remote access to Half-Life Dedicated Server, Source Dedicated Server or even a Minecraft server.

You can use it with any kind of process with input/output, even bash, cmd.exe or powershell.exe, but I wouldn't recommend it 😄

Features

• SSH protocol for remote access
• Client IP filtering
• Restart process on success/failure
• Pass a configurable set of input commands to the process on startup
• Run as a systemd service on unix platforms, with Type=notify
• Run as a Windows service

Known issues

• SSH resize events are not necessarily forwarded to the pseudoterminal (but any ANSI escape sequences sent by an SSH client may be forwarded). The pseudoterminal has a fixed size.

Possible configuration values

A default configuration file config.json is generated when you launch prochost. You can modify this accordingly.

Settings for the process:

• process.workingDir: Working directory to spawn the process in (optional, defaults to current directory)
• process.path: Path to executable
• process.arguments: Arguments to pass to executable (defaults to no arguments)
• process.environment: Environment to pass to executable (optional)
• process.inheritEnvironment: Whether the process should inherit the same environment prochost has (in addition to extra environment variables passed)
• process.successExitCodes: A list of exit codes considered a successful termination of the process (defaults to [0])
• process.restartOnSuccess: Whether to restart the process if it exited with a successful exit code (as defined by process.successExitCode, defaults to true)
• process.restartOnFailure: Whether to restart the process if it exited with a non-successful exit code (as defined by process.successExitCode, defaults to false)
• process.restartDelay: How long to wait before restarting the process (defaults to 5 seconds)
• process.startupInput: Any input to pass to the process after startup (defaults to [])
• process.delayBeforeStartupInput: Delay before passing process.startupInput to the process (defaults to 1 second)
• process.delayBetweenStartupInput: Delay between passing each element in the process.startupInput list to the process (defaults to 10 milliseconds)
• process.inputBufferSize: How many byte arrays for input data to buffer in memory at the same time before dropping any (defaults to 100)
• process.outputBufferSize: How many byte arrays for output data to buffer in memory at the same time before dropping any (defaults to 100)

Settings for the SSH server:

• server.listen: Listen address/port. Possible formats:

  • <IPv4>[:<port>] - example: 127.0.0.1, 127.0.0.1:22000 or 0.0.0.0:22000
  • <IPv6> - example: ::1 or ::
  • [<IPv6>][:<port>] - example: [::1]:22000 or [::]:22000
  • <hostname>[:<port>] - example: localhost:22000

• server.maxConnections: Maximum allowed client connections

• server.users: List of users to allow (default: []). Allows any user if empty. Format:

  [{
    "username": "username",
    "passwordHash": "$2a$12$Z0u0zCO.2FwfEl.6N7KxIeAs2J5zUzHouORhHdBk0WDOhKzrQcxSO",
    "allowedNetworksCIDR": []
  }]

• server.allowedNetworksCIDR: List of networks in CIDR format to allow client connections from (default: []). Allows any client IP address if empty or not provided.

• server.hostKeys: An array of OpenSSH private keys. An ed25519 and RSA host key is generated automatically when config.json is generated.

• server.serverId: SSH Server ID (default: SSH-2.0-prochost_0.1.0)

• server.authRejectionTime: Time before an invalid authentication attempt is rejected

• server.maxAuthAttempts: Maximum number of authentication attempts before a client is disconnected

• server.inactivityTimeout: Time before a client is disconnected due to inactivity (optional)

• server.keepaliveInterval: If nothing is received from the client for this amount of time, send a keepalive message (optional)

• server.keepaliveMax: If this many keepalives have been sent without reply, close the connection (default: 3)

• server.nodelay: If active, invoke set_nodelay(true) on client sockets; disabled by default (i.e. Nagle's algorithm is active)