公认的答案是异步的。我想要一个同步版本:

var os = require('os');
var ifaces = os.networkInterfaces();

console.log(JSON.stringify(ifaces, null, 4));

for (var iface in ifaces) {
  var iface = ifaces[iface];
  for (var alias in iface) {
    var alias = iface[alias];

    console.log(JSON.stringify(alias, null, 4));

    if ('IPv4' !== alias.family || alias.internal !== false) {
      debug("skip over internal (i.e. 127.0.0.1) and non-IPv4 addresses");
      continue;
    }
    console.log("Found IP address: " + alias.address);
    return alias.address;
  }
}
return false;

类似于其他答案，但更简洁:

'use strict';

const interfaces = require('os').networkInterfaces();

const addresses = Object.keys(interfaces)
  .reduce((results, name) => results.concat(interfaces[name]), [])
  .filter((iface) => iface.family === 'IPv4' && !iface.internal)
  .map((iface) => iface.address);

对于Underscore.js和Lodash，正确的一行代码是:

var ip = require('underscore')
    .chain(require('os').networkInterfaces())
    .values()
    .flatten()
    .find({family: 'IPv4', internal: false})
    .value()
    .address;

这是我的变体，允许以可移植的方式获得IPv4和IPv6地址:

/**
 * Collects information about the local IPv4/IPv6 addresses of
 * every network interface on the local computer.
 * Returns an object with the network interface name as the first-level key and
 * "IPv4" or "IPv6" as the second-level key.
 * For example you can use getLocalIPs().eth0.IPv6 to get the IPv6 address
 * (as string) of eth0
 */
getLocalIPs = function () {
    var addrInfo, ifaceDetails, _len;
    var localIPInfo = {};
    //Get the network interfaces
    var networkInterfaces = require('os').networkInterfaces();
    //Iterate over the network interfaces
    for (var ifaceName in networkInterfaces) {
        ifaceDetails = networkInterfaces[ifaceName];
        //Iterate over all interface details
        for (var _i = 0, _len = ifaceDetails.length; _i < _len; _i++) {
            addrInfo = ifaceDetails[_i];
            if (addrInfo.family === 'IPv4') {
                //Extract the IPv4 address
                if (!localIPInfo[ifaceName]) {
                    localIPInfo[ifaceName] = {};
                }
                localIPInfo[ifaceName].IPv4 = addrInfo.address;
            } else if (addrInfo.family === 'IPv6') {
                //Extract the IPv6 address
                if (!localIPInfo[ifaceName]) {
                    localIPInfo[ifaceName] = {};
                }
                localIPInfo[ifaceName].IPv6 = addrInfo.address;
            }
        }
    }
    return localIPInfo;
};

下面是同一个函数的CoffeeScript版本:

getLocalIPs = () =>
    ###
    Collects information about the local IPv4/IPv6 addresses of
      every network interface on the local computer.
    Returns an object with the network interface name as the first-level key and
      "IPv4" or "IPv6" as the second-level key.
    For example you can use getLocalIPs().eth0.IPv6 to get the IPv6 address
      (as string) of eth0
    ###
    networkInterfaces = require('os').networkInterfaces();
    localIPInfo = {}
    for ifaceName, ifaceDetails of networkInterfaces
        for addrInfo in ifaceDetails
            if addrInfo.family=='IPv4'
                if !localIPInfo[ifaceName]
                    localIPInfo[ifaceName] = {}
                localIPInfo[ifaceName].IPv4 = addrInfo.address
            else if addrInfo.family=='IPv6'
                if !localIPInfo[ifaceName]
                    localIPInfo[ifaceName] = {}
                localIPInfo[ifaceName].IPv6 = addrInfo.address
    return localIPInfo

console.log(getLocalIPs())的示例输出

{ lo: { IPv4: '127.0.0.1', IPv6: '::1' },
  wlan0: { IPv4: '192.168.178.21', IPv6: 'fe80::aa1a:2eee:feba:1c39' },
  tap0: { IPv4: '10.1.1.7', IPv6: 'fe80::ddf1:a9a1:1242:bc9b' } }

下面是一段Node.js代码，它将解析ifconfig的输出并(异步地)返回找到的第一个IP地址:

(它只在Mac OS X v10.6 (Snow Leopard)上测试;我希望它也能在Linux上运行。)

var getNetworkIP = (function () {
    var ignoreRE = /^(127\.0\.0\.1|::1|fe80(:1)?::1(%.*)?)$/i;

    var exec = require('child_process').exec;
    var cached;
    var command;
    var filterRE;

    switch (process.platform) {
        // TODO: implement for OSes without the ifconfig command
        case 'darwin':
             command = 'ifconfig';
             filterRE = /\binet\s+([^\s]+)/g;
             // filterRE = /\binet6\s+([^\s]+)/g; // IPv6
             break;
        default:
             command = 'ifconfig';
             filterRE = /\binet\b[^:]+:\s*([^\s]+)/g;
             // filterRE = /\binet6[^:]+:\s*([^\s]+)/g; // IPv6
             break;
    }

    return function (callback, bypassCache) {
        // Get cached value
        if (cached && !bypassCache) {
            callback(null, cached);
            return;
        }

        // System call
        exec(command, function (error, stdout, sterr) {
            var ips = [];
            // Extract IP addresses
            var matches = stdout.match(filterRE);

            // JavaScript doesn't have any lookbehind regular expressions, so we need a trick
            for (var i = 0; i < matches.length; i++) {
                ips.push(matches[i].replace(filterRE, '$1'));
            }

            // Filter BS
            for (var i = 0, l = ips.length; i < l; i++) {
                if (!ignoreRE.test(ips[i])) {
                    //if (!error) {
                        cached = ips[i];
                    //}
                    callback(error, ips[i]);
                    return;
                }
            }
            // Nothing found
            callback(error, null);
        });
    };
})();

使用的例子:

getNetworkIP(function (error, ip) {
    console.log(ip);
    if (error) {
        console.log('error:', error);
    }
}, false);

如果第二个参数为true，函数将每次执行一次系统调用;否则使用缓存的值。

更新版本

返回所有本地网络地址的数组。

在Ubuntu 11.04 (Natty Narwhal)和Windows XP 32上测试

var getNetworkIPs = (function () {
    var ignoreRE = /^(127\.0\.0\.1|::1|fe80(:1)?::1(%.*)?)$/i;

    var exec = require('child_process').exec;
    var cached;
    var command;
    var filterRE;

    switch (process.platform) {
        case 'win32':
        //case 'win64': // TODO: test
            command = 'ipconfig';
            filterRE = /\bIPv[46][^:\r\n]+:\s*([^\s]+)/g;
            break;
        case 'darwin':
            command = 'ifconfig';
            filterRE = /\binet\s+([^\s]+)/g;
            // filterRE = /\binet6\s+([^\s]+)/g; // IPv6
            break;
        default:
            command = 'ifconfig';
            filterRE = /\binet\b[^:]+:\s*([^\s]+)/g;
            // filterRE = /\binet6[^:]+:\s*([^\s]+)/g; // IPv6
            break;
    }

    return function (callback, bypassCache) {
        if (cached && !bypassCache) {
            callback(null, cached);
            return;
        }

        // System call
        exec(command, function (error, stdout, sterr) {
            cached = [];
            var ip;
            var matches = stdout.match(filterRE) || [];
            //if (!error) {
            for (var i = 0; i < matches.length; i++) {
                ip = matches[i].replace(filterRE, '$1')
                if (!ignoreRE.test(ip)) {
                    cached.push(ip);
                }
            }
            //}
            callback(error, cached);
        });
    };
})();

使用举例:升级版本

getNetworkIPs(function (error, ip) {
console.log(ip);
if (error) {
    console.log('error:', error);
}
}, false);

根据注释，以下是当前版本Node.js的工作原理:

var os = require('os');
var _ = require('lodash');

var ip = _.chain(os.networkInterfaces())
  .values()
  .flatten()
  .filter(function(val) {
    return (val.family == 'IPv4' && val.internal == false)
  })
  .pluck('address')
  .first()
  .value();

上面一个答案的注释缺少对values()的调用。看起来os.networkInterfaces()现在返回一个对象而不是数组。