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SCTP network protocol RFC4960 in plain js


npm i @nodertc/sctp


const securesocket = dtls.connect(/*...*/);

const socket = sctp.connect({
  localPort: 5000,
  port: 5000,
  transport: securesocket,

socket.on('connect', socket => {
  console.log('socket connected')
  socket.write(Buffer.from('010003010000001000110008000003ea', 'hex'))

socket.on('data', buffer => {
  console.log('socket received data from server', buffer.toString())

In UDP mode host and localAddress will be ignored, because addressing is provided by underlying transport.

Also note that in most cases "passive" connect is a better alternative to creating server.

passive option disables active connect to remote peer. Socket waits for remote connection, allowing it only from indicated remote port. This unusual option doesn't exist in TCP API.

new net.Socket([options])

  • options [Object]

For SCTP socketss, available options are:

  • ppid [number] Payload protocol id (see below)
  • stream_id [number] SCTP stream id. Default: 0
  • unordered [boolean] Indicate unordered mode. Default: false
  • no_bundle [boolean] Disable chunk bundling. Default: false

Note: SCTP does not support a half-open state (like TCP) wherein one side may continue sending data while the other end is closed.

socket.connect(options[, connectListener])

  • options [Object]
  • connectListener [Function] Common parameter of socket.connect() methods. Will be added as a listener for the 'connect' event once.

For SCTP connections, available options are:

  • port [number] Required. Port the socket should connect to.
  • host [string] Host the socket should connect to. Default: 'localhost'
  • localAddress [string] Local address the socket should connect from.
  • localPort [number] Local port the socket should connect from.
  • MIS [number] Maximum inbound streams. Default: 2
  • OS [number] Requested outbound streams. Default: 2
  • passive [boolean] Indicates passive mode. Socket will not connect, but allow connection of remote socket from host:port. Default: false
  • transport [stream.Duplex] Any valid Duplex stream.


Creates SCTP stream with stream id. Those are SCTP socket sub-streams.

After the association is initialized, the valid outbound stream identifier range for either endpoint shall be 0 to min(local OS, remote MIS)-1.

You can check this negotiated value by referring to socket.OS after 'connect' event. id should be less the socket.OS.

Result is stream.Writable.

const stream = socket.createStream(1)
stream.write('some data')

Socket events

See Net module documentation.

For SCTP additional event 'stream' is defined. It signals that incoming data chunk were noticed with new SCTP stream id.

socket.on('stream', (stream, id) => {
  stream.on('data', data => {
    // Incoming data


Function sets default module parameters. Names follow net.sctp conventions. Returns current default parameters.

See sysctl -a | grep sctp


  rto_initial: 500,
  rto_min: 300,
  rto_max: 1000,
  sack_timeout: 150,
  sack_freq: 2,


sctp.PPID is an object with SCTP Payload Protocol Identifiers

  SCTP: 0,
  IUA: 1,
  M2UA: 2,
  M3UA: 3,
  SUA: 4,
  M2PA: 5,
  V5UA: 6,
  H248: 7,
  BICC: 8,

RFC to implement


  • MIT, 2017-2018 © Vladimir Latyshev
  • MIT, 2018 © Dmitriy Tsvettsikh

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