Fix IPv6 hostname formatting in CLI

packages/next/cli/next-dev.ts

@@ -13,6 +13,7 @@ import path from 'path'
 import type { NextConfig } from '../types'
 import type { NextConfigComplete } from '../server/config-shared'
 import { traceGlobals } from '../trace/shared'
+import { isIPv6 } from 'net'
 
 let isTurboSession = false
 let sessionStopHandled = false
@@ -419,7 +420,8 @@ If you cannot make the changes above, but still want to try out\nNext.js v13 wit
     startServer(devServerOptions)
       .then(async (app) => {
         const appUrl = `http://${app.hostname}:${app.port}`
-        startedDevelopmentServer(appUrl, `${host || '0.0.0.0'}:${app.port}`)
+        const hostname = host ? (isIPv6(host) ? `[${host}]` : host) : '0.0.0.0'
+        startedDevelopmentServer(appUrl, `${hostname}:${app.port}`)
         // Start preflight after server is listening and ignore errors:
         preflight().catch(() => {})
         // Finalize server bootup:

packages/next/cli/next-start.ts

@@ -7,6 +7,7 @@ import * as Log from '../build/output/log'
 import isError from '../lib/is-error'
 import { getProjectDir } from '../lib/get-project-dir'
 import { cliCommand } from '../lib/commands'
+import { isIPv6 } from 'net'
 
 const nextStart: cliCommand = (argv) => {
   const validArgs: arg.Spec = {
@@ -80,7 +81,8 @@ const nextStart: cliCommand = (argv) => {
   })
     .then(async (app) => {
       const appUrl = `http://${app.hostname}:${app.port}`
-      Log.ready(`started server on ${host}:${app.port}, url: ${appUrl}`)
+      const hostname = isIPv6(host) ? `[${host}]` : host
+      Log.ready(`started server on ${hostname}:${app.port}, url: ${appUrl}`)
       await app.prepare()
     })
     .catch((err) => {

packages/next/server/lib/start-server.ts

@@ -2,6 +2,7 @@ import type { NextServerOptions, NextServer, RequestHandler } from '../next'
 import { warn } from '../../build/output/log'
 import http from 'http'
 import next from '../next'
+import { isIPv6 } from 'net'
 
 interface StartServerOptions extends NextServerOptions {
   allowRetry?: boolean
@@ -52,6 +53,10 @@ export function startServer(opts: StartServerOptions) {
       const hostname =
         !opts.hostname || opts.hostname === '0.0.0.0'
           ? 'localhost'
+          : isIPv6(opts.hostname)
+          ? opts.hostname === '::'
+            ? `[${opts.hostname}1]`
+            : `[${opts.hostname}]`
           : opts.hostname
 
       const app = next({