ftp.js

const FtpSrv = require("ftp-srv");
const { Netmask } = require("netmask");
const { networkInterfaces } = require('os');

const nets = networkInterfaces();

const user = "user";
const pw = "pw";

const host = process.argv[2] || "localhost";
const port = process.argv[3] || 21;

const getNetworks = () => {
    let networks = {};
    for (const name of Object.keys(nets)) {
        for (const net of nets[name]) {
            if (net.family === 'IPv4' && !net.internal) {
                networks[net.address + "/24"] = net.address
            }
        }
    }
    return networks;
};

const resolverFunction = (ip) => {
    const networks = getNetworks();
    for (const network in networks) {
        if (new Netmask(network).contains(ip)) {
            return networks[network];
        }
    }
    return "0.0.0.0";
};

const ftpServer = new FtpSrv({
    url: `ftp://${host}:${port}`,
    pasv_url: resolverFunction,
    pasv_min: 60000,
    pasv_max: 60009,
    anonymous: true
});

ftpServer.on("login", ({ connection, username, password }, resolve, reject) => {

    connection.on("RETR", (error, filePath) => {
        if (error) console.log(`File download error: ${error}`);
        else console.log(`File downloaded: ${filePath}`);
    });

    connection.on("STOR", (error, filePath) => {
        if (error) console.log(`File upload error: ${error}`);
        else console.log(`File uploaded: ${filePath}`);
    });

    if (username === user && password === pw) {
        return resolve({ root: "./files" });
    }
    console.log("Invalid username or password");
    return reject(new errors.GeneralError("Invalid username or password", 401));
});

ftpServer.on("client-error", ({ connection, context, error }) => {
    console.log(`Client error at ${context}: ${error}`);
});

ftpServer.listen().then(() => {
    console.log(`Ftp server started at ftp://${host}:${port}...`);
    console.log(`Test file url: ftp://${user}:${pw}@${host}:${port}/[filename]`);
});