mininet

Spin up and interact with virtual networks using Mininet and Node.js

npm install mininet

Usage

const Mininet = require('mininet')

const mn = new Mininet()

// create a switch
const s1 = mn.createSwitch()

// create some hosts
const h1 = mn.createHost()
const h2 = mn.createHost()

// link them to the switch
h1.link(s1)
h2.link(s1)

// start the network
mn.start()

// run a server in node
const proc = h1.spawn('node server.js')

proc.on('message:listening', function () {
  // when h1 signals it is listening, run curl
  const proc2 = h2.spawn('curl --silent ' + h1.ip + ':10000')

  proc2.on('stdout', function (data) {
    process.stdout.write('h2 ' + data)
    mn.stop() // stop when h2 messages
  })
})

proc.on('stdout', function (data) {
  process.stdout.write('h1 ' + data)
})

Assuming server.js looks like this

const http = require('http')
const mn = require('mininet/host')

const server = http.createServer(function (req, res) {
  console.log('Server responding')
  res.end('hello from server\n')
})

server.listen(10000, function () {
  console.log('Server listening on', this.address().port)
  mn.send('listening') // msg the host
})

API

const mn = new Mininet([options])

Create a new mininet instance. Options include

{
  clean: false,         // if true run mn -c first
  sudo: true,           // use sudo if needed
  sock: '/tmp/mn.sock', // explictly set the .sock file used
  debug: false,         // set to true to enable debug output
  stdio: null,          // passed to host.spawn as a default option
  prefixStdio: false    // passed to host.spawn as a default option
}

If for some reason your mininet instance stops working you probably wanna try using clean: true.

mn.start([callback])

Start the mininet network. Usually you call this after defining your hosts, switches and links.

After the network has fully started start is emitted.

mn.stop([callback])

Stop the mininet network. You should not call any other methods after this.

After the network has fully stopped stop is emitted.

mn.switches

Array of all created switches.

mn.hosts

Array of all created hosts.

const sw = mn.createSwitch()

Create a new switch

sw.link(other, [options])

Link the switch with another switch or host. Options include:

{
  bandwidth: 10,  // use 10mbit link
  delay: '100ms', // 100ms delay
  loss: 10,       // 10% package loss
  htb: true       // use htb
}

const host = mn.createHost()

Create an new host

host.ip

The IP address of the host. Populated after the network is started.

host.mac

The MAC address of the host. Populated after the network is started.

host.link(other, [options])

Link the host with another host or switch. Takes the same options as sw.link.

host.exec(cmd, [callback])

Execute a command and buffer the output and return it in the callback.

const proc = host.spawn(cmd, [options])

Spawn a new process to run the in background of the host. Options include:

{
  stdio: 'inherit', // set this to forward stdio
  prefixStdio: 'some-prefix' // all stdio is prefixed with this
}

If you set prefixStdio: true it will be converted to {host.id}.{process.id}. When debugging it can be useful to set both {stdio: 'inherit', prefixStdio: true}.

const proc = host.spawnNode(programSource, [options])

Helper that spawns a Node.js source inside the host. Useful when using multiline strings

host.spawnNode(
  `
  console.log('starting timer...')
  setInterval(() => console.log('Time is', Date.now()))
`,
  {
    stdio: 'inherit',
    prefixStdio: true
  }
)

proc.id

Unique string id of the process

proc.kill([signal])

Kill the process.

proc.send(type, data)

Send a message to the process.

proc.on('stdout', data)

Emitted when the process has output.

proc.on('message', type, data)

Emitted when the process received a message.

proc.on('message:{type}', data)

Same as above but with the type as part of the event name for convenience.

proc.on('exit')

Emitted when the process exits.

Messaging

If you are spawning a node process you can require mininet/host to communicate with the host.

const host = require('mininet/host')

Require this in a spawned process.

host.send(type, data)

Send a message to the host.

host.sendTo(processId, type, data)

Send a message to another process.

host.broadcast(type, data)

Send a message to all processes.

host.on('message', type, data, metadata)

Emitted when a message is received from the host. The metadata argument contains the following data

{
  from: 'some-process-id-or-host' // who sent this message
}

host.on('message:{type}', data, metadata)

Same as above but with the type as part of the event name for convenience.

License

MIT