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    net-keepalive
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    3.0.0 • Public • Published

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    🔗 net-keepalive

    NPM

    The Missing (TCP_KEEPINTVL and TCP_KEEPCNT) SO_KEEPALIVE socket option setters and getters for Node using ffi-napi module.

    Tested on 🐧 linux & 🍏 osx (both amd64 and arm64), should work on 😈 freebsd and others. Installs on 🐄 win32 🎉 but methods are no-ops (pull requests welcome).

    There's also support for getting & setting the TCP_USER_TIMEOUT (🐧 linux and 🍏 osx only) option, which is closely related to keep-alive.

    Platform support

    Platform TCP_KEEPINTVL TCP_KEEPCNT TCP_USER_TIMEOUT
    🐧 linux
    🍏 osx (TCP_RXT_CONNDROPTIME)
    😈 freebsd
    🐄 win32

    Legend:

    • - Supported
    • - No operation
    • - Unsupported (throws)

    Install

    npm install --save net-keepalive

    Documentation

    You can find the full API Reference Document (JSDoc) published on our github pages.

    The project includes TypeScript definitions file (index.d.ts) which gives an overview of the API exposed.

    Documentation gets generated from JSDoc comments, feel free to improve them by sending pull requests.

    Demo

    const Net = require('net'),
      NetKeepAlive = require('net-keepalive')
    // or
    import * as Net from 'net'
    import * as NetKeepAlive from 'net-keepalive'
    
    // Create a TCP Server
    const srv = Net.createServer((s) => {
      console.log('Connected %j', s.address())
      // Doesn't matter what it does
      s.pipe(s)
    })
    
    // Start on some port
    srv.listen(1337, () => {
      console.log('Listening on %j', srv.address())
    })
    
    // Connect to that server
    const s = Net.createConnection({ port: 1337 }, () => {
      console.log('Connected to %j', s.address())
    
      //IMPORTANT: KeepAlive must be enabled for this to work
      s.setKeepAlive(true, 1000)
    
      // Set TCP_KEEPINTVL for this specific socket
      NetKeepAlive.setKeepAliveInterval(s, 1000)
    
      // Get TCP_KEEPINTVL for this specific socket
      NetKeepAlive.getKeepAliveInterval(s) // 1000
    
      // Set TCP_KEEPCNT for this specific socket
      NetKeepAlive.setKeepAliveProbes(s, 1)
    
      // Get TCP_KEEPCNT for this specific socket
      NetKeepAlive.getKeepAliveProbes(s) // 1
    })

    Now using iptables add rule to drop all tcp packets on INPUT chain to port 1337.

    iptables -I INPUT -m tcp -p tcp --dport 1337 -j DROP

    If you were monitoring packets on loopback with tcp.srcport == 1337 || tcp.dstport == 1337 filter in wireshark. You will see the following output:

    Wireshark screenshot KEEPALIVE

    Have fun!

    More info about SO_KEEPALIVE here: TCP Keepalive HOWTO C Code examples here: Examples

    Sample

    Note: For these methods to work you must enable SO_KEEPALIVE and set the TCP_KEEPIDLE options for socket using Net.Socket-s built in method socket.setKeepAlive([enable][, initialDelay]) !

    TCP_KEEPIDLE (since Linux 2.4) The time (in seconds) the connection needs to remain idle before TCP starts sending keepalive probes, if the socket option SO_KEEPALIVE has been set on this socket. This option should not be used in code intended to be portable.
    
    const NetKeepAlive = require('net-keepalive')
    // or
    import * as NetKeepAlive from 'net-keepalive'
    
    // .....
    
    const enable = true                                             // enable SO_KEEPALIVE
    const initialDuration = 1000                                    // start probing after 1 second of inactivity
    socket.setKeepAlive(enable, initialDuration)                    // sets SO_KEEPALIVE and TCP_KEEPIDLE
    
    const probeInterval = 1000                                      // after initialDuration send probes every 1 second
    NetKeepAlive.setKeepAliveInterval(socket, probeInterval)        //sets TCP_KEEPINTVL
    
    const maxProbesBeforeFail = 10                                  // after 10 failed probes connection will be dropped
    NetKeepAlive.setKeepAliveProbes(socket, maxProbesBeforeFail)    // sets TCP_KEEPCNT
    
    // ....

    Code of Conduct

    See CODE_OF_CONDUCT.md

    Contributing

    See CONTRIBUTING.md

    Contributors

    Thanks goes to these wonderful people (emoji key):


    George Hertz

    🚧 💻 📖 ⚠️ 📦 💬

    Alba Mendez

    💻 📖 ⚠️

    Paulo Castro

    🐛

    Jacob Jewell

    🐛

    RMutharaju

    🛡️

    Rafael Borges

    🐛

    Calvin

    🐛

    ggsubs

    🐛

    Mario Kozjak

    🐛

    Lukas Knuth

    💻

    This project follows the all-contributors specification. Contributions of any kind welcome!

    Install

    npm i net-keepalive

    DownloadsWeekly Downloads

    6,109

    Version

    3.0.0

    License

    MIT

    Unpacked Size

    27.6 kB

    Total Files

    9

    Last publish

    Collaborators

    • hertzg