General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Wi-Fi (general): How to modernize your captive network developer news post Wi-Fi Fundamentals forums post Filing a Wi-Fi Bug Report forums post Working with a Wi-Fi Accessory forums post — This is part of the Extra-ordinary Networking series. Wi-Fi (iOS): TN3111 iOS Wi-Fi API overview technote Wi-Fi Aware framework documentation WirelessInsights framework documentation iOS Network Signal Strength forums post Network Extension Resources Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

How often do we see control filter start and stop? I read somewhere that data filter is long lived and control Filter is short lived. When does the operating system kills the control filter process?

Hello, I understand that to discover and pair a device or accessory with Wi-Fi Aware, we can use either the DeviceDiscoveryUI or AccessorySetupKitUI frameworks. During the pairing process, both frameworks prompt the user to enter a pairing code. Is this step mandatory? What alternatives exist for devices or accessories that don't have a way to communicate a pairing code to the user (for example, devices or accessories without a display or voice capability)? Best regards, Gishan

Every now and again folks notice that Network framework seems to create an unexpected number of connections on the wire. This post explains why that happens and what you should do about it. If you have questions or comments, put them in a new thread here on the forums. Use the App & System Services > Networking topic area and the Network tag. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Understanding Also-Ran Connections Network framework implements the Happy Eyeballs algorithm. That might create more on-the-wire connections than you expect. There are two common places where folks notice this: When looking at a packet trace When implementing a listener Imagine that you’ve implemented a TCP server using NWListener and you connect to it from a client using NWConnection. In many situations there are multiple network paths between the client and the server. For example, on a local network there’s always at least two paths: the link-local IPv6 path and either an infrastructure IPv4 path or the link-local IPv4 path. When you start your NWConnection, Network framework’s Happy Eyeballs algorithm might [1] start a TCP connection for each of these paths. It then races those connections. The one that connects first is the ‘winner’, and Network framework uses that connection for your traffic. Once it has a winner, the other connections, the also-ran connections, are redundant, and Network framework just closes them. You can observe this behaviour on the client side by looking in the system log. Many Network framework log entries (subsystem com.apple.network) contain a connection identifier. For example C8 is the eighth connection started by this process. Each connection may have child connections (C8.1, C8.2, …) and grandchild connections (C8.1.1, C8.1.2, …), and so on. You’ll see state transitions for these child connections occurring in parallel. For example, the following log entries show that C8 is racing the connection of two grandchild connections, C8.1.1 and C8.1.2: type: debug time: 12:22:26.825331+0100 process: TestAlsoRanConnections subsystem: com.apple.network category: connection message: nw_socket_connect [C8.1.1:1] Calling connectx(…) type: debug time: 12:22:26.964150+0100 process: TestAlsoRanConnections subsystem: com.apple.network category: connection message: nw_socket_connect [C8.1.2:1] Calling connectx(…) Note For more information about accessing the system log, see Your Friend the System Log. You also see this on the server side, but in this case each connection is visible to your code. When you connect from the client, Network framework calls your listener’s new connection handler with multiple connections. One of those is the winning connection and you’ll receive traffic on it. The others are the also-ran connections, and they close promptly. IMPORTANT Depending on network conditions there may be no also-ran connections. Or there may be lots of them. If you want to test the also-ran connection case, use Network Link Conditioner to add a bunch of delay to your packets. You don’t need to write special code to handle also-ran connections. From the perspective of your listener, these are simply connections that open and then immediately close. There’s no difference between an also-ran connection and, say, a connection from a client that immediately crashes. Or a connection generated by someone doing a port scan. Your server must be resilient to such things. However, the presence of these also-ran connections can be confusing, especially if you’re just getting started with Network framework, and hence this post. [1] This is “might” because the exact behaviour depends on network conditions. More on that below.

Hi, We're receiving data via centralManager.centralManager.scanForPeripherals, with no options or filtering (for now), and in the func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) callback, we get advertisementData for each bluetooth device found. But, I know one of my BLE devices is sending an Eddystone TLM payload, which generally is received into the kCBAdvDataServiceData part of the advertisementData dictionary, but, it doesn't show up. What is happening however (when comparing to other devices that do show that payload), is I've noticed the "isConnectable" part is false, and others have it true. Technically we're not "connecting" as such as we're simply reading passive advertisement data, but does that have any bearing on how CoreBluetooth decides to build up it's AdvertisementData response? Example (with serviceData; and I know this has Eddystone TLM) ["kCBAdvDataLocalName": FSC-BP105N, "kCBAdvDataRxPrimaryPHY": 1, "kCBAdvDataServiceUUIDs": <__NSArrayM 0x300b71f80>( FEAA, FEF5 ) , "kCBAdvDataTimestamp": 773270526.26279, "kCBAdvDataServiceData": { FFF0 = {length = 11, bytes = 0x36021892dc0d3015aeb164}; FEAA = {length = 14, bytes = 0x20000be680000339ffa229bbce8a}; }, "kCBAdvDataRxSecondaryPHY": 0, "kCBAdvDataIsConnectable": 1] Vs This also has Eddystone TLM configured ["kCBAdvDataLocalName": 100FA9FD-7000-1000, "kCBAdvDataIsConnectable": 0, "kCBAdvDataRxPrimaryPHY": 1, "kCBAdvDataRxSecondaryPHY": 0, "kCBAdvDataTimestamp": 773270918.97273] Any insight would be great to understand if the presence of other flags drive the exposure of ServiceData or not...

HI, I am currently developing an app that utilizes Wi-Fi Aware. According to the Wi-Fi Aware framework examples and the WWDC25 session on Wi-Fi Aware, discovery is handled using DevicePairingView and DevicePicker from the DeviceDiscoveryUI module. However, these SwiftUI views present their connection UI modally when tapped. My app's design requires the ability to control the presentation of this UI programmatically, rather than relying on a user tap. While inspecting the DeviceDiscoveryUI module, I found DDDevicePairingViewController and DDDevicePickerViewController, which appear to be the UIViewController counterparts to the SwiftUI views. The initializer for DDDevicePairingViewController accepts a ListenerProvider, so it seems I can pass the same ListenerProvider instance that is used with the DevicePairingView. However, the initializer for DDDevicePickerViewController requires an NWBrowser.Descriptor, which seems incompatible with the parameters used for the SwiftUI DevicePicker. I have two main questions: (1) Can DDDevicePairingViewController and DDDevicePickerViewController be officially used for Wi-Fi Aware pairing? (2) Are there any plans to provide more customization or programmatic control over the DevicePairingView and DevicePicker (for example, allowing us to trigger their modal presentation programmatically)? Thank you.

General: Forums subtopic: App & System Services > Networking DevForums tag: Network Extension Network Extension framework documentation Routing your VPN network traffic article Filtering traffic by URL sample code Filtering Network Traffic sample code TN3120 Expected use cases for Network Extension packet tunnel providers technote TN3134 Network Extension provider deployment technote TN3165 Packet Filter is not API technote Network Extension and VPN Glossary forums post Debugging a Network Extension Provider forums post Exporting a Developer ID Network Extension forums post Network Extension Framework Entitlements forums post Network Extension vs ad hoc techniques on macOS forums post Network Extension Provider Packaging forums post NWEndpoint History and Advice forums post Extra-ordinary Networking forums post Wi-Fi management: Understanding NEHotspotConfigurationErrorInternal forums post See also Networking Resources for general networking resources, including information about Wi-Fi. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

At WWDC 2015 Apple announced two major enhancements to the Network Extension framework: Network Extension providers — These are app extensions that let you insert your code at various points within the networking stack, including: Packet tunnels via NEPacketTunnelProvider App proxies via NEAppProxyProvider Content filters via NEFilterDataProvider and NEFilterControlProvider Hotspot Helper (NEHotspotHelper) — This allows you to create an app that assists the user in navigating a hotspot (a Wi-Fi network where the user must interact with the network in order to get access to the wider Internet). Originally, using any of these facilities required authorisation from Apple. Specifically, you had to apply for, and be granted access to, a managed capability. In Nov 2016 this policy changed for Network Extension providers. Any developer can now use the Network Extension provider capability like they would any other capability. There is one exception to this rule: Network Extension app push providers, introduced by iOS 14 in 2020, still requires that Apple authorise the use of a managed capability. To apply for that, follow the link in Local push connectivity. Also, the situation with Hotspot Helpers remains the same: Using a Hotspot Helper, requires that Apple authorise that use via a managed capability. To apply for that, follow the link in Hotspot helper. IMPORTANT Pay attention to this quote from the documentation: NEHotspotHelper is only useful for hotspot integration. There are both technical and business restrictions that prevent it from being used for other tasks, such as accessory integration or Wi-Fi based location. The rest of this document answers some frequently asked questions about the Nov 2016 change. #1 — Has there been any change to the OS itself? No, this change only affects the process by which you get the capabilities you need in order to use existing Network Extension framework facilities. Previously these were managed capabilities, meaning their use was authorised by Apple. Now, except for app push providers and Hotspot Helper, you can enable the necessary capabilities using Xcode’s Signing & Capabilities editor or the Developer website. IMPORTANT Some Network Extension providers have other restrictions on their use. For example, a content filter can only be used on a supervised device. These restrictions are unchanged. See TN3134 Network Extension provider deployment for the details. #2 — How exactly do I enable the Network Extension provider capability? In the Signing & Capabilities editor, add the Network Extensions capability and then check the box that matches the provider you’re creating. In the Certificates, Identifiers & Profiles section of the Developer website, when you add or edit an App ID, you’ll see a new capability listed, Network Extensions. Enable that capability in your App ID and then regenerate the provisioning profiles based on that App ID. A newly generated profile will include the com.apple.developer.networking.networkextension entitlement in its allowlist; this is an array with an entry for each of the supported Network Extension providers. To confirm that this is present, dump the profile as shown below. $ security cms -D -i NETest.mobileprovision … <plist version="1.0"> <dict> … <key>Entitlements</key> <dict> <key>com.apple.developer.networking.networkextension</key> <array> <string>packet-tunnel-provider</string> <string>content-filter-provider</string> <string>app-proxy-provider</string> … and so on … </array> … </dict> … </dict> </plist> #3 — I normally use Xcode’s Signing & Capabilities editor to manage my entitlements. Do I have to use the Developer website for this? No. Xcode 11 and later support this capability in the Signing & Capabilities tab of the target editor (r. 28568128 ). #4 — Can I still use Xcode’s “Automatically manage signing” option? Yes. Once you modify your App ID to add the Network Extension provider capability, Xcode’s automatic code signing support will include the entitlement in the allowlist of any profiles that it generates based on that App ID. #5 — What should I do if I previously applied for the Network Extension provider managed capability and I’m still waiting for a reply? Consider your current application cancelled, and use the new process described above. #6 — What should I do if I previously applied for the Hotspot Helper managed capability and I’m still waiting for a reply? Apple will continue to process Hotspot Helper managed capability requests and respond to you in due course. #7 — What if I previously applied for both Network Extension provider and Hotspot Helper managed capabilities? Apple will ignore your request for the Network Extension provider managed capability and process it as if you’d only asked for the Hotspot Helper managed capability. #8 — On the Mac, can Developer ID apps host Network Extension providers? Yes, but there are some caveats: This only works on macOS 10.15 or later. Your Network Extension provider must be packaged as a system extension, not an app extension. You must use the *-systemextension values for the Network Extension entitlement (com.apple.developer.networking.networkextension). For more on this, see Exporting a Developer ID Network Extension. #9 — After moving to the new process, my app no longer has access to the com.apple.managed.vpn.shared keychain access group. How can I regain that access? Access to this keychain access group requires another managed capability. If you need that, please open a DTS code-level support request and we’ll take things from there. IMPORTANT This capability is only necessary if your VPN supports configuration via a configuration profile and needs to access credentials from that profile (as discussed in the Profile Configuration section of the NETunnelProviderManager Reference). Many VPN apps don’t need this facility. If you were previously granted the Network Extension managed capability (via the process in place before Nov 2016), make sure you mention that; restoring your access to the com.apple.managed.vpn.shared keychain access group should be straightforward in that case. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-11-11 Removed the discussion of TSI assets because those are no longer a thing. 2025-09-12 Adopted the code-level support request terminology. Made other minor editorial changes. 2023-01-11 Added a discussion of Network Extension app push providers. Added a link to Exporting a Developer ID Network Extension. Added a link to TN3134. Made significant editorial changes. 2020-02-27 Fixed the formatting. Updated FAQ#3. Made minor editorial changes. 2020-02-16 Updated FAQ#8 to account for recent changes. Updated FAQ#3 to account for recent Xcode changes. Made other editorial changes. 2016-01-25 Added FAQ#9. 2016-01-6 Added FAQ#8. 2016-11-11 Added FAQ#5, FAQ#6 and FAQ#7. 2016-11-11 First posted.

Questions about FTP crop up from time-to-time here on DevForums. In most cases I write a general “don’t use FTP” response, but I don’t have time to go into all the details. I’ve created this post as a place to collect all of those details, so I can reference them in other threads. IMPORTANT Apple’s official position on FTP is: All our FTP APIs have been deprecated, and you should avoid using deprecated APIs. Apple has been slowly removing FTP support from the user-facing parts of our system. The most recent example of this is that we removed the ftp command-line tool in macOS 10.13. You should avoid the FTP protocol and look to adopt more modern alternatives. The rest of this post is an informational explanation of the overall FTP picture. This post is locked so I can keep it focused. If you have questions or comments, please do create a new thread in the App & System Services > Networking subtopic and I’ll respond there. Don’t Use FTP FTP is a very old and very crufty protocol. Certain things that seem obvious to us now — like being able to create a GUI client that reliably shows a directory listing in a platform-independent manner — aren’t possible to do in FTP. However, by far the biggest problem with FTP is that it provides no security [1]. Specifically, the FTP protocol: Provides no on-the-wire privacy, so anyone can see the data you transfer Provides no client-authenticates-server authentication, so you have no idea whether you’re talking to the right server Provides no data integrity, allowing an attacker to munge your data in transit Transfers user names and passwords in the clear Using FTP for anonymous downloads may be acceptable (see the explanation below) but most other uses of FTP are completely inappropriate for the modern Internet. IMPORTANT You should only use FTP for anonymous downloads if you have an independent way to check the integrity of the data you’ve downloaded. For example, if you’re downloading a software update, you could use code signing to check its integrity. If you don’t check the integrity of the data you’ve downloaded, an attacker could substitute a malicious download instead. This would be especially bad in, say, the software update case. These fundamental problems with the FTP protocol mean that it’s not a priority for Apple. This is reflected in the available APIs, which is the subject of the next section. FTP APIs Apple provides two FTP APIs: All Apple platforms provide FTP downloads via URLSession. Most Apple platforms (everything except watchOS) support CFFTPStream, which allows for directory listings, downloads, uploads, and directory creation. All of these FTP APIs are now deprecated: URLSession was deprecated for the purposes of FTP in the 2022 SDKs (macOS 13, iOS 16, iPadOS 16, tvOS 16, watchOS 9) [2]. CFFTPStream was deprecated in the 2016 SDKs (macOS 10.11, iOS 9, iPadOS 9, tvOS 9). CFFTPStream still works about as well as it ever did, which is not particularly well. Specifically: There is at least one known crashing bug (r. 35745763), albeit one that occurs quite infrequently. There are clear implementation limitations — like the fact that CFFTPCreateParsedResourceListing assumes a MacRoman text encoding (r. 7420589) — that won’t be fixed. If you’re looking for an example of how to use these APIs, check out SimpleFTPSample. Note This sample hasn’t been updated since 2013 and is unlikely to ever be updated given Apple’s position on FTP. The FTP support in URLSession has significant limitations: It only supports FTP downloads; there’s no support for uploads or any other FTP operations. It doesn’t support resumable FTP downloads [3]. It doesn’t work in background sessions. That prevents it from running FTP downloads in the background on iOS. It’s only supported in classic loading mode. See the usesClassicLoadingMode property and the doc comments in <Foundation/NSURLSession.h>. If Apple’s FTP APIs are insufficient for your needs, you’ll need to write or acquire your own FTP library. Before you do that, however, consider switching to an alternative protocol. After all, if you’re going to go to the trouble of importing a large FTP library into your code base, you might as well import a library for a better protocol. The next section discusses some options in this space. Alternative Protocols There are numerous better alternatives to FTP: HTTPS is by far the best alternative to FTP, offering good security, good APIs on Apple platforms, good server support, and good network compatibility. Implementing traditional FTP operations over HTTPS can be a bit tricky. One possible way forward is to enable DAV extensions on the server. FTPS is FTP over TLS (aka SSL). While FTPS adds security to the protocol, which is very important, it still inherits many of FTP’s other problems. Personally I try to avoid this protocol. SFTP is a file transfer protocol that’s completely unrelated to FTP. It runs over SSH, making it a great alternative in many of the ad hoc setups that traditionally use FTP. Apple doesn’t have an API for either FTPS or SFTP, although on macOS you may be able to make some headway by invoking the sftp command-line tool. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] In another thread someone asked me about FTP’s other problems, those not related to security, so let’s talk about that. One of FTP’s implicit design goals was to provide cross-platform support that exposes the target platform. You can think of FTP as being kinda like telnet. When you telnet from Unix to VMS, it doesn’t aim to abstract away VMS commands, so that you can type Unix commands at the VMS prompt. Rather, you’re expected to run VMS commands. FTP is (a bit) like that. This choice made sense back when the FTP protocol was invented. Folks were expecting to use FTP via a command-line client, so there was a human in the loop. If they ran a command and it produced VMS-like output, that was fine because they knew that they were FTPing into a VMS machine. However, most users today are using GUI clients, and this design choice makes it very hard to create a general GUI client for FTP. Let’s consider the simple problem of getting the contents of a directory. When you send an FTP LIST command, the server would historically run the platform native directory list command and pipe the results back to you. To create a GUI client you have to parse that data to extract the file names. Doing that is a serious challenge. Indeed, just the first step, working out the text encoding, is a challenge. Many FTP servers use UTF-8, but some use ISO-Latin-1, some use other standard encodings, some use Windows code pages, and so on. I say “historically” above because there have been various efforts to standardise this stuff, both in the RFCs and in individual server implementations. However, if you’re building a general client you can’t rely on these efforts. After all, the reason why folks continue to use FTP is because of it widespread support. [2] To quote the macOS 13 Ventura Release Notes: FTP is deprecated for URLSession and related APIs. Please adopt modern secure networking protocols such as HTTPS. (92623659) [3] Although you can implement resumable downloads using the lower-level CFFTPStream API, courtesy of the kCFStreamPropertyFTPFileTransferOffset property. Revision History 2025-10-06 Explained that URLSession only supports FTP in classic loading mode. Made other minor editorial changes. 2024-04-15 Added a footnote about FTP’s other problems. Made other minor editorial changes. 2022-08-09 Noted that the FTP support in URLSession is now deprecated. Made other minor editorial changes. 2021-04-06 Fixed the formatting. Fixed some links. 2018-02-23 First posted.

Most apps perform ordinary network operations, like fetching an HTTP resource with URLSession and opening a TCP connection to a mail server with Network framework. These operations are not without their challenges, but they’re the well-trodden path. If your app performs ordinary networking, see TN3151 Choosing the right networking API for recommendations as to where to start. Some apps have extra-ordinary networking requirements. For example, apps that: Help the user configure a Wi-Fi accessory Require a connection to run over a specific interface Listen for incoming connections Building such an app is tricky because: Networking is hard in general. Apple devices support very dynamic networking, and your app has to work well in whatever environment it’s running in. Documentation for the APIs you need is tucked away in man pages and doc comments. In many cases you have to assemble these APIs in creative ways. If you’re developing an app with extra-ordinary networking requirements, this post is for you. Note If you have questions or comments about any of the topics discussed here, put them in a new thread here on DevForums. Make sure I see it by putting it in the App & System Services > Networking area. And feel free to add tags appropriate to the specific technology you’re using, like Foundation, CFNetwork, Network, or Network Extension. Links, Links, and More Links Each topic is covered in a separate post: The iOS Wi-Fi Lifecycle describes how iOS joins and leaves Wi-Fi networks. Understanding this is especially important if you’re building an app that works with a Wi-Fi accessory. Network Interface Concepts explains how Apple platforms manage network interfaces. If you’ve got this far, you definitely want to read this. Network Interface Techniques offers a high-level overview of some of the more common techniques you need when working with network interfaces. Network Interface APIs describes APIs and core techniques for working with network interfaces. It’s referenced by many other posts. Running an HTTP Request over WWAN explains why most apps should not force an HTTP request to run over WWAN, what they should do instead, and what to do if you really need that behaviour. If you’re building an iOS app with an embedded network server, see Showing Connection Information in an iOS Server for details on how to get the information to show to your user so they can connect to your server. Many folks run into trouble when they try to find the device’s IP address, or other seemingly simple things, like the name of the Wi-Fi interface. Don’t Try to Get the Device’s IP Address explains why these problems are hard, and offers alternative approaches that function correctly in all network environments. Similarly, folks also run into trouble when trying to get the host name. On Host Names explains why that’s more complex than you might think. If you’re working with broadcasts or multicasts, see Broadcasts and Multicasts, Hints and Tips. If you’re building an app that works with a Wi-Fi accessory, see Working with a Wi-Fi Accessory. If you’re trying to gather network interface statistics, see Network Interface Statistics. There are also some posts that are not part of this series but likely to be of interest if you’re working in this space: TN3179 Understanding local network privacy discusses the local network privacy feature. Calling BSD Sockets from Swift does what it says on the tin, that is, explains how to call BSD Sockets from Swift. When doing weird things with the network, you often find yourself having to use BSD Sockets, and that API is not easy to call from Swift. The code therein is primarily for the benefit of test projects, oh, and DevForums posts like these. TN3111 iOS Wi-Fi API overview is a critical resource if you’re doing Wi-Fi specific stuff on iOS. TLS For Accessory Developers tackles the tricky topic of how to communicate securely with a network-based accessory. A Peek Behind the NECP Curtain discusses NECP, a subsystem that control which programs have access to which network interfaces. Networking Resources has links to many other useful resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-07-31 Added a link to A Peek Behind the NECP Curtain. 2025-03-28 Added a link to On Host Names. 2025-01-16 Added a link to Broadcasts and Multicasts, Hints and Tips. Updated the local network privacy link to point to TN3179. Made other minor editorial changes. 2024-04-30 Added a link to Network Interface Statistics. 2023-09-14 Added a link to TLS For Accessory Developers. 2023-07-23 First posted.

ios構成プロファイルの制限のallowCloudPrivateRelayのプライベートリレーの制御とRelayペイロードの機能は関係がありますか？ それとも別々の機能でしょうか？ ↓ s there a relationship between the private relay control in the iOS configuration profile restriction allowCloudPrivateRelay and the functionality of the Relay payload? Or are they separate features?

Hi there, We’re developing a companion app for a smart home product that communicates over the user’s local network. To provision the device, it initially creates its own Wi-Fi network. The user joins this temporary network and enters their home Wi-Fi credentials via our app. The app then sends those credentials directly to the device, which stores them and connects to the local network for normal operation. We’re using AccessorySetupKit to discover nearby devices (via SSID prefix) and NEHotspotManager to join the accessory’s Wi-Fi network once the user selects it. This workflow works well in general. However, we’ve encountered a problem: if the user factory-resets the accessory, or needs to restart setup (for example, after entering the wrong Wi-Fi password), the device no longer appears in the accessory picker. In iOS 18, we were able to work around this by calling removeAccessory() after the device is selected. This forces the picker to always display the accessory again. But in iOS 26, a new confirmation dialog now appears when calling removeAccessory(), which confuses users during setup. We’re looking for a cleaner way to handle this scenario — ideally a way to make the accessory rediscoverable without prompting the user to confirm removal. Thanks for your time and guidance.

Starting in iOS 26, two notable changes have been made to CallKit, LiveCommunicationKit, and the PushToTalk framework: As a diagnostic aid, we're introducing new dialogs to warn apps of voip push related issue, for example when they fail to report a call or when when voip push delivery stops. The specific details of that behavior are still being determined and are likely to change over time, however, the critical point here is that these alerts are only intended to help developers debug and improve their app. Because of that, they're specifically tied to development and TestFlight signed builds, so the alert dialogs will not appear for customers running app store builds. The existing termination/crashes will still occur, but the new warning alerts will not appear. As PushToTalk developers have previously been warned, the last unrestricted PushKit entitlement ("com.apple.developer.pushkit.unrestricted-voip.ptt") has been disabled in the iOS 26 SDK. ALL apps that link against the iOS 26 SDK which receive a voip push through PushKit and which fail to report a call to CallKit will be now be terminated by the system, as the API contract has long specified. __ Kevin Elliott DTS Engineer, CoreOS/Hardware

Are the network relays introduced in 2023 and https://aninterestingwebsite.com/videos/play/wwdc2023/10002/ the same thing as the Private Relay introduced in 2021? https://aninterestingwebsite.com/videos/play/wwdc2021/10096/ We are considering verifying the relay function, but we are not sure whether they are the same function or different functions. https://aninterestingwebsite.com/documentation/devicemanagement/relay?language=objc

The path from Network Extension’s in-provider networking APIs to Network framework has been long and somewhat rocky. The most common cause of confusion is NWEndpoint, where the same name can refer to two completely different types. I’ve helped a bunch of folks with this over the years, and I’ve decided to create this post to collect together all of those titbits. If you have questions or comments, please put them in a new thread. Put it in the App & System Services > Networking subtopic and tag it with Network Extension. That way I’ll be sure to see it go by. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" NWEndpoint History and Advice A tale that spans three APIs, two languages, and ten years. The NWEndpoint type has a long and complex history, and if you’re not aware of that history you can bump into weird problems. The goal of this post is to explain the history and then offer advice on how to get around specific problems. IMPORTANT This post focuses on NWEndpoint, because that’s the type that causes the most problems, but there’s a similar situation with NWPath. The History In iOS 9 Apple introduced the Network Extension (NE) framework, which offers a convenient way for developers to create a custom VPN transport. Network Extension types all have the NE prefix. Note I’m gonna use iOS versions here, just to keep the text simple. If you’re targeting some other platform, use this handy conversion table: iOS | macOS | tvOS | watchOS | visionOS --- + ----- + ---- + ------- + -------- 9 | 10.11 | 9 | 2 | - 12 | 10.14 | 12 | 5 | - 18 | 15 | 18 | 11 | 2 At that time we also introduced in-provider networking APIs. The idea was that an NE provider could uses these Objective-C APIs to communicate with its VPN server, and thereby avoiding a bunch of ugly BSD Sockets code. The in-provider networking APIs were limited to NE providers. Specifically, the APIs to construct an in-provider connection were placed on types that were only usable within an NE provider. For example, a packet tunnel provider could create a NWTCPConnection object by calling -createTCPConnectionToEndpoint:enableTLS:TLSParameters:delegate:] and -createTCPConnectionThroughTunnelToEndpoint:enableTLS:TLSParameters:delegate:, which are both methods on NEPacketTunnelProvider. These in-provider networking APIs came with a number of ancillary types, including NWEndpoint and NWPath. At the time we thought that we might promote these in-provider networking APIs to general-purpose networking APIs. That’s why the APIs use the NW prefix. For example, it’s NWTCPConnection, not NETCPConnection. However, plans changed. In iOS 12 Apple shipped Network framework as our recommended general-purpose networking API. This actually includes two APIs: A Swift API that follows Swift conventions, for example, the connection type is called NWConnection A C API that follows C conventions, for example, the connection type is called nw_connection_t These APIs follow similar design patterns to the in-provider networking API, and thus have similar ancillary types. Specifically, there are an NWEndpoint and nw_endpoint_t types, both of which perform a similar role to the NWEndpoint type in the in-provider networking API. This was a source of some confusion in Swift, because the name NWEndpoint could refer to either the Network framework type or the Network Extension framework type, depending on what you’d included. Fortunately you could get around this by qualifying the type as either Network.NWEndpoint or NetworkExtension.NWEndpoint. The arrival of Network framework meant that it no longer made sense to promote the in-provider networking APIs to general-purposes networking APIs. The in-provider networking APIs were on the path to deprecation. However, deprecating these APIs was actually quite tricky. Network Extension framework uses these APIs in a number of interesting ways, and so deprecating them required adding replacements. In addition, we’d needed different replacements for Swift and Objective-C, because Network framework has separate APIs for Swift and C-based languages. In iOS 18 we tackled that problem head on. To continue the NWTCPConnection example above, we replaced: -createTCPConnectionToEndpoint:enableTLS:TLSParameters:delegate:] with nw_connection_t -createTCPConnectionThroughTunnelToEndpoint:enableTLS:TLSParameters:delegate: with nw_connection_t combined with a new virtualInterface property on NEPacketTunnelProvider Of course that’s the Objective-C side of things. In Swift, the replacement is NWConnection rather than nw_connection_t, and the type of the virtualInterface property is NWInterface rather than nw_interface_t. But that’s not the full story. For the two types that use the same name in both frameworks, NWEndpoint and NWPath, we decided to use this opportunity to sort out that confusion. To see how we did that, check out the <NetworkExtension/NetworkExtension.apinotes> file in the SDK. Focusing on NWEndpoint for the moment, you’ll find two entries: … - Name: NWEndpoint SwiftPrivate: true … SwiftVersions: - Version: 5.0 … - Name: NWEndpoint SwiftPrivate: false … The first entry applies when you’re building with the Swift 6 language mode. This marks the type as SwiftPrivate, which means that Swift imports it as __NWEndpoint. That frees up the NWEndpoint name to refer exclusively to the Network framework type. The second entry applies when you’re building with the Swift 5 language mode. It marks the type as not SwiftPrivate. This is a compatible measure to ensure that code written for Swift 5 continues to build. The Advice This sections discusses specific cases in this transition. NWEndpoint and NWPath In Swift 5 language mode, NWEndpoint and NWPath might refer to either framework, depending on what you’ve imported. Add a qualifier if there’s any ambiguity, for example, Network.NWEndpoint or NetworkExtension.NWEndpoint. In Swift 6 language mode, NWEndpoint and NWPath always refer to the Network framework type. Add a __ prefix to get to the Network Extension type. For example, use NWEndpoint for the Network framework type and __NWEndpoint for the Network Extension type. Direct and Through-Tunnel TCP Connections in Swift To create a connection directly, simply create an NWConnection. This support both TCP and UDP, with or without TLS. To create a connection through the tunnel, replace code like this: let c = self.createTCPConnectionThroughTunnel(…) with code like this: let params = NWParameters.tcp params.requiredInterface = self.virtualInterface let c = NWConnection(to: …, using: params) This is for TCP but the same basic process applies to UDP. UDP and App Proxies in Swift If you’re building an app proxy, transparent proxy, or DNS proxy in Swift and need to handle UDP flows using the new API, adopt the NEAppProxyUDPFlowHandling protocol. So, replace code like this: class AppProxyProvider: NEAppProxyProvider { … override func handleNewUDPFlow(_ flow: NEAppProxyUDPFlow, initialRemoteEndpoint remoteEndpoint: NWEndpoint) -> Bool { … } } with this: class AppProxyProvider: NEAppProxyProvider, NEAppProxyUDPFlowHandling { … func handleNewUDPFlow(_ flow: NEAppProxyUDPFlow, initialRemoteFlowEndpoint remoteEndpoint: NWEndpoint) -> Bool { … } } Creating a Network Rule To create an NWHostEndpoint, replace code like this: let ep = NWHostEndpoint(hostname: "1.2.3.4", port: "12345") let r = NENetworkRule(destinationHost: ep, protocol: .TCP) with this: let ep = NWEndpoint.hostPort(host: "1.2.3.4", port: 12345) let r = NENetworkRule(destinationHostEndpoint: ep, protocol: .TCP) Note how the first label of the initialiser has changed from destinationHost to destinationHostEndpoint.

This is a topic that’s come up a few times on the forums, so I thought I’d write up a summary of the issues I’m aware of. If you have questions or comments, start a new thread in the App & System Services > Networking subtopic and tag it with Network Extension. That way I’ll be sure to see it go by. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Extension Provider Packaging There are two ways to package a network extension provider: App extension ( appex ) System extension ( sysex ) Different provider types support different packaging on different platforms. See TN3134 Network Extension provider deployment for the details. Some providers, most notably packet tunnel providers on macOS, support both appex and sysex packaging. Sysex packaging has a number of advantages: It supports direct distribution, using Developer ID signing. It better matches the networking stack on macOS. An appex is tied to the logged in user, whereas a sysex, and the networking stack itself, is global to the system as a whole. Given that, it generally makes sense to package your Network Extension (NE) provider as a sysex on macOS. If you’re creating a new product that’s fine, but if you have an existing iOS product that you want to bring to macOS, you have to account for the differences brought on by the move to sysex packaging. Similarly, if you have an existing sysex product on macOS that you want to bring to iOS, you have to account for the appex packaging. This post summarises those changes. Keep the following in mind while reading this post: The information here applies to all NE providers that can be packaged as either an appex or a sysex. When this post uses a specific provider type in an example, it’s just an example. Unless otherwise noted, any information about iOS also applies to iPadOS, tvOS, and visionOS. Process Lifecycle With appex packaging, the system typically starts a new process for each instance of your NE provider. For example, with a packet tunnel provider: When the users starts the VPN, the system creates a process and then instantiates and starts the NE provider in that process. When the user stops the VPN, the system stops the NE provider and then terminates the process running it. If the user starts the VPN again, the system creates an entirely new process and instantiates and starts the NE provider in that. In contrast, with sysex packaging there’s typically a single process that runs all off the sysex’s NE providers. Returning to the packet tunnel provider example: When the users starts the VPN, the system instantiates and starts the NE provider in the sysex process. When the user stops the VPN, the system stops and deallocates the NE provider instances, but leaves the sysex process running. If the user starts the VPN again, the system instantiates and starts a new instances of the NE provider in the sysex process. This lifecycle reflects how the system runs the NE provider, which in turn has important consequences on what the NE provider can do: An appex acts like a launchd agent [1], in that it runs in a user context and has access to that user’s state. A sysex is effectively a launchd daemon. It runs in a context that’s global to the system as a whole. It does not have access to any single user’s state. Indeed, there might be no user logged in, or multiple users logged in. The following sections explore some consequences of the NE provider lifecycle. [1] It’s not actually run as a launchd agent. Rather, there’s a system launchd agent that acts as the host for the app extension. App Groups With an app extension, the app extension and its container app run as the same user. Thus it’s trivial to share state between them using an app group container. Note When talking about extensions on Apple platforms, the container app is the app in which the extension is embedded and the host app is the app using the extension. For network extensions the host app is the system itself. That’s not the case with a system extension. The system extension runs as root whereas the container app runs an the user who launched it. While both programs can claim access to the same app group, the app group container location they receive will be different. For the system extension that location will be inside the home directory for the root user. For the container app the location will be inside the home directory of the user who launched it. This does not mean that app groups are useless in a Network Extension app. App groups are also a factor in communicating between the container app and its extensions, the subject of the next section. IMPORTANT App groups have a long and complex history on macOS. For the full story, see App Groups: macOS vs iOS: Working Towards Harmony. Communicating with Extensions With an app extension there are two communication options: App-provider messages App groups App-provider messages are supported by NE directly. In the container app, send a message to the provider by calling sendProviderMessage(_:responseHandler:) method. In the appex, receive that message by overriding the handleAppMessage(_:completionHandler:) method. An appex can also implement inter-process communication (IPC) using various system IPC primitives. Both the container app and the appex claim access to the app group via the com.apple.security.application-groups entitlement. They can then set up IPC using various APIs, as explain in the documentation for that entitlement. With a system extension the story is very different. App-provider messages are supported, but they are rarely used. Rather, most products use XPC for their communication. In the sysex, publish a named XPC endpoint by setting the NEMachServiceName property in its Info.plist. Listen for XPC connections on that endpoint using the XPC API of your choice. Note For more information about the available XPC APIs, see XPC Resources. In the container app, connect to that named XPC endpoint using the XPC Mach service name API. For example, with NSXPCConnection, initialise the connection with init(machServiceName:options:), passing in the string from NEMachServiceName. To maximise security, set the .privileged flag. Note XPC Resources has a link to a post that explains why this flag is important. If the container app is sandboxed — necessary if you ship on the Mac App Store — then the endpoint name must be prefixed by an app group ID that’s accessible to that app, lest the App Sandbox deny the connection. See the app groups documentation for the specifics. When implementing an XPC listener in your sysex, keep in mind that: Your sysex’s named XPC endpoint is registered in the global namespace. Any process on the system can open a connection to it [1]. Your XPC listener must be prepared for this. If you want to restrict connections to just your container app, see XPC Resources for a link to a post that explains how to do that. Even if you restrict access in that way, it’s still possible for multiple instances of your container app to be running simultaneously, each with its own connection to your sysex. This happens, for example, if there are multiple GUI users logged in and different users run your container app. Design your XPC protocol with this in mind. Your sysex only gets one named XPC endpoint, and thus one XPC listener. If your sysex includes multiple NE providers, take that into account when you design your XPC protocol. [1] Assuming that connection isn’t blocked by some other mechanism, like the App Sandbox. Inter-provider Communication A sysex can include multiple types of NE providers. For example, a single sysex might include a content filter and a DNS proxy provider. In that case the system instantiates all of the NE providers in the same sysex process. These instances can communicate without using IPC, for example, by storing shared state in global variables (with suitable locking, of course). It’s also possible for a single container app to contain multiple sysexen, each including a single NE provider. In that case the system instantiates the NE providers in separate processes, one for each sysex. If these providers need to communicate, they have to use IPC. In the appex case, the system instantiates each provider in its own process. If two providers need to communicate, they have to use IPC. Managing Secrets An appex runs in a user context and thus can store secrets, like VPN credentials, in the keychain. On macOS this includes both the data protection keychain and the file-based keychain. It can also use a keychain access group to share secrets with its container app. See Sharing access to keychain items among a collection of apps. Note If you’re not familiar with the different types of keychain available on macOS, see TN3137 On Mac keychain APIs and implementations. A sysex runs in the global context and thus doesn’t have access to user state. It also doesn’t have access to the data protection keychain. It must use the file-based keychain, and specifically the System keychain. That means there’s no good way to share secrets with the container app. Instead, do all your keychain operations in the sysex. If the container app needs to work with a secret, have it pass that request to the sysex via IPC. For example, if the user wants to use a digital identity as a VPN credential, have the container app get the PKCS#12 data and password and then pass that to the sysex so that it can import the digital identity into the keychain. Memory Limits iOS imposes strict memory limits an NE provider appexen [1]. macOS imposes no memory limits on NE provider appexen or sysexen. [1] While these limits are not documented officially, you can get a rough handle on the current limits by reading the posts in this thread. Frameworks If you want to share code between a Mac app and its embedded appex, use a structure like this: MyApp.app/ Contents/ MacOS/ MyApp PlugIns/ MyExtension.appex/ Contents/ MacOS/ MyExtension … Frameworks/ MyFramework.framework/ … There’s one copy of the framework, in the app’s Frameworks directory, and both the app and the appex reference it. This approach works for an appex because the system always loads the appex from your app’s bundle. It does not work for a sysex. When you activate a sysex, the system copies it to a protected location. If that sysex references a framework in its container app, it will fail to start because that framework isn’t copied along with the sysex. The solution is to structure your app like this: MyApp.app/ Contents/ MacOS/ MyApp Library/ SystemExtensions/ MyExtension.systemextension/ Contents/ MacOS/ MyExtension Frameworks/ MyFramework.framework/ … … That is, have both the app and the sysex load the framework from the sysex’s Frameworks directory. When the system copies the sysex to its protected location, it’ll also copy the framework, allowing the sysex to load it. To make this work you have to change the default rpath configuration set up by Xcode. Read Dynamic Library Standard Setup for Apps to learn how that works and then tweak things so that: The framework is embedded in the sysex, not the container app. The container app has an additional LC_RPATH load command for the sysex’s Frameworks directory (@executable_path/../Library/SystemExtensions/MyExtension.systemextension/Contents/Frameworks). The sysex’s LC_RPATH load command doesn’t reference the container app’s Frameworks directory (@executable_path/../../../../Frameworks) but instead points to the sysex’s Framweorks directory (@executable_path/../Frameworks). Entitlements When you build an app with an embedded NE extension, both the app and the extension must be signed with the com.apple.developer.networking.networkextension entitlement. This is a restricted entitlement, that is, it must be authorised by a provisioning profile. The value of this entitlement is an array, and the values in that array differ depend on your distribution channel: If you distribute your app directly with Developer ID signing, use the values with the -systemextension suffix. Otherwise — including when you distribute the app on the App Store and when signing for development — use the values without that suffix. Make sure you authorise these values with your provisioning profile. If, for example, you use an App Store distribution profile with a Developer ID signed app, things won’t work because the profile doesn’t authorise the right values. In general, the easiest option is to use Xcode’s automatic code signing. However, watch out for the pitfall described in Exporting a Developer ID Network Extension. Revision History 2025-11-06 Added the Entitlements section. Explained that, with sysex packaging, multiple instances of your container app might connect simultaneously with your sysex. 2025-09-17 First posted.

Hello Apple Support Team, We are seeing a production crash on iOS 26 devices that appears to originate from Apple system frameworks rather than application code. Crash Summary Crash signature: _xzm_xzone_malloc_freelist_outlined Crashed thread: com.apple.network.connections Frameworks involved: CFNetwork, Security, libdispatch, libsystem_malloc Affected OS: iOS 26.x App built with: Xcode 16 Devices: Multiple models (not device-specific) Reproducibility: Intermittent, higher frequency during app launch / background networking Observed Stack Trace (top frames) _xzm_xzone_malloc_freelist_outlined dispatch_data_create_alloc xpc_data_deserialize SecTrustEvaluateIfNecessary CFNetwork HTTPProtocol / HTTP3Connection com.apple.network.connections App Context The app uses URLSession for networking. Multiple third-party SDKs are integrated (Firebase Analytics, Dynatrace, Appsflyer, and similar analytics/monitoring SDKs). These SDKs perform concurrent background network requests, especially during app launch and foreground transitions. No unsafe memory operations (manual malloc/free, unsafe pointers, or custom networking stacks) are used in the app code. Key Observations The crash is predominantly observed on iOS 26 and not on earlier iOS versions. Stack traces do not include application symbols. Disabling or delaying analytics SDK initialization significantly reduces the crash rate. Reducing concurrent network requests and limiting HTTP/3 usage also mitigates the issue. This suggests a potential regression in CFNetwork / Network.framework / HTTP/3 handling combined with the new memory allocator (xzone) on iOS 26. Impact Random app termination during background networking. Occurs without a clear deterministic repro path, making it difficult to fully mitigate at the app level. Request Could you please help investigate whether this is a known iOS 26 issue related to: HTTP/3 / QUIC networking XPC deserialization Memory allocation in the new xzone allocator High-concurrency network requests We would appreciate guidance on: Recommended mitigations Whether this issue is already tracked internally Any best practices for apps integrating multiple analytics SDKs on iOS 26 Crash logs and additional diagnostics can be provided if needed. Thank you for your support. Best regards, Dhananjay

Hello, Our app uses Network Extension / Packet Tunnel Provider to establish VPN connections on macOS and iOS. We have observed that after creating a utun device and adding any IPv4 routes (NEPacketTunnelNetworkSettings.IPv4Settings), the OS automatically adds several host routes via utun to services such as Akamai, Apple Push, etc. These routes appear to correspond to TCP flows that were active at the moment the VPN connection was established. When a particular TCP flow ends, the corresponding host route is deleted. We understand this is likely intended to avoid breaking existing TCP connections. However, we find the behavior of migrating existing TCP flows to the new utun interface simply because any IPv4 route is added somewhat questionable. This approach would make sense in a "full-tunnel" scenario — for example, when all IPv4 traffic (e.g., 0.0.0.0/0) is routed through the tunnel — but not necessarily in a "split-tunnel" configuration where only specific IPv4 routes are added. Is there any way to control or influence this behavior? Would it be possible for FlowDivert to differentiate between full-tunnel and split-tunnel cases, and only preserve existing TCP flows via utun in the full-tunnel scenario? Thank you.

I'm using NERelayManager to set Relay configuration which all works perfectly fine. I then do a curl with the included domain and while I see QUIC connection succeeds with relay server and H3 request goes to the server, the connection gets abruptly closed by the client with "Software caused connection abort". Console has this information: default 09:43:04.459517-0700 curl nw_flow_connected [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] Transport protocol connected (quic) default 09:43:04.459901-0700 curl [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:finish_transport @0.131s default 09:43:04.460745-0700 curl nw_flow_connected [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] Joined protocol connected (http3) default 09:43:04.461049-0700 curl [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:finish_transport @0.133s default 09:43:04.465115-0700 curl [C2 E47A3A0C-7275-4F6B-AEDF-59077ABAE34B 192.168.4.197:4433 quic, multipath service: 1, tls, definite, attribution: developer] cancel default 09:43:04.465238-0700 curl [C2 E47A3A0C-7275-4F6B-AEDF-59077ABAE34B 192.168.4.197:4433 quic, multipath service: 1, tls, definite, attribution: developer] cancelled [C2 FCB1CFD1-4BF9-4E37-810E-81265D141087 192.168.4.139:53898<->192.168.4.197:4433] Connected Path: satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi Duration: 0.121s, QUIC @0.000s took 0.000s, TLS 1.3 took 0.111s bytes in/out: 2880/4322, packets in/out: 4/8, rtt: 0.074s, retransmitted bytes: 0, out-of-order bytes: 0 ecn packets sent/acked/marked/lost: 3/1/0/0 default 09:43:04.465975-0700 curl nw_flow_disconnected [C2 192.168.4.197:4433 cancelled multipath-socket-flow ((null))] Output protocol disconnected default 09:43:04.469189-0700 curl nw_endpoint_proxy_receive_report [C1.1 IPv4#124bdc4d:80 in_progress proxy (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, proxy, uses wifi)] Privacy proxy failed with error 53 ([C1.1.1] masque Proxy: http://192.168.4.197:4433) default 09:43:04.469289-0700 curl [C1.1.1 192.168.4.197:4433 failed socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:failed_connect @0.141s, error Software caused connection abort Relay server otherwise works fine with our QUIC MASQUE clients but not with built-in macOS MASQUE client. Anything I'm missing?

On "Accessory Interface Specification CarPlay Addendum R10", it says that it is recommended that the accessory uses a MIMO (2x2) hardware configuration, does this imply that WiFi 5 and SISO (1X1) will be phased out in the near future? When will WiFi 6 MIMO (2x2) become mandatory? On "Accessory Interface Specification CarPlay Addendum R10", it says that Spatial Audio is mandatory. However, for aftermarket in-vehicle infotainment (IVI) system due to the number of speakers are less than 6, is it allowed not to support spatial audio for this type of aftermarket IVI system?

For important background information, read Extra-ordinary Networking before reading this. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Interface APIs Most developers don’t need to interact directly with network interfaces. If you do, read this post for a summary of the APIs available to you. Before you read this, read Network Interface Concepts. Interface List The standard way to get a list of interfaces and their addresses is getifaddrs. To learn more about this API, see its man page. A network interface has four fundamental attributes: A set of flags — These are packed into a CUnsignedInt. The flags bits are declared in <net/if.h>, starting with IFF_UP. An interface type — See Network Interface Type, below. An interface index — Valid indexes are greater than 0. A BSD interface name. For example, an Ethernet interface might be called en0. The interface name is shared between multiple network interfaces running over a given hardware interface. For example, IPv4 and IPv6 running over that Ethernet interface will both have the name en0. WARNING BSD interface names are not considered API. There’s no guarantee, for example, that an iPhone’s Wi-Fi interface is en0. You can map between the last two using if_indextoname and if_nametoindex. See the if_indextoname man page for details. An interface may also have address information. If present, this always includes the interface address (ifa_addr) and the network mask (ifa_netmask). In addition: Broadcast-capable interfaces (IFF_BROADCAST) have a broadcast address (ifa_broadaddr, which is an alias for ifa_dstaddr). Point-to-point interfaces (IFF_POINTOPOINT) have a destination address (ifa_dstaddr). Calling getifaddrs from Swift is a bit tricky. For an example of this, see QSocket: Interfaces. IP Address List Once you have getifaddrs working, it’s relatively easy to manipulate the results to build a list of just IP addresses, a list of IP addresses for each interface, and so on. QSocket: Interfaces has some Swift snippets that show this. Interface List Updates The interface list can change over time. Hardware interfaces can be added and removed, network interfaces come up and go down, and their addresses can change. It’s best to avoid caching information from getifaddrs. If thats unavoidable, use the kNotifySCNetworkChange Darwin notification to update your cache. For information about registering for Darwin notifications, see the notify man page (in section 3). This notification just tells you that something has changed. It’s up to you to fetch the new interface list and adjust your cache accordingly. You’ll find that this notification is sometimes posted numerous times in rapid succession. To avoid unnecessary thrashing, debounce it. While the Darwin notification API is easy to call from Swift, Swift does not import kNotifySCNetworkChange. To fix that, define that value yourself, calling a C function to get the value: var kNotifySCNetworkChange: UnsafePointer<CChar> { networkChangeNotifyKey() } Here’s what that C function looks like: extern const char * networkChangeNotifyKey(void) { return kNotifySCNetworkChange; } Network Interface Type There are two ways to think about a network interface’s type. Historically there were a wide variety of weird and wonderful types of network interfaces. The following code gets this legacy value for a specific BSD interface name: func legacyTypeForInterfaceNamed(_ name: String) -> UInt8? { var addrList: UnsafeMutablePointer<ifaddrs>? = nil let err = getifaddrs(&addrList) // In theory we could check `errno` here but, honestly, what are gonna // do with that info? guard err >= 0, let first = addrList else { return nil } defer { freeifaddrs(addrList) } return sequence(first: first, next: { $0.pointee.ifa_next }) .compactMap { addr in guard let nameC = addr.pointee.ifa_name, name == String(cString: nameC), let sa = addr.pointee.ifa_addr, sa.pointee.sa_family == AF_LINK, let data = addr.pointee.ifa_data else { return nil } return data.assumingMemoryBound(to: if_data.self).pointee.ifi_type } .first } The values are defined in <net/if_types.h>, starting with IFT_OTHER. However, this value is rarely useful because many interfaces ‘look like’ Ethernet and thus have a type of IFT_ETHER. Network framework has the concept of an interface’s functional type. This is an indication of how the interface fits into the system. There are two ways to get an interface’s functional type: If you’re using Network framework and have an NWInterface value, get the type property. If not, call ioctl with a SIOCGIFFUNCTIONALTYPE request. The return values are defined in <net/if.h>, starting with IFRTYPE_FUNCTIONAL_UNKNOWN. Swift does not import SIOCGIFFUNCTIONALTYPE, so it’s best to write this code in a C: extern uint32_t functionalTypeForInterfaceNamed(const char * name) { int fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } struct ifreq ifr = {}; strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); bool success = ioctl(fd, SIOCGIFFUNCTIONALTYPE, &ifr) >= 0; int junk = close(fd); assert(junk == 0); if ( ! success ) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } return ifr.ifr_ifru.ifru_functional_type; } Finally, TN3158 Resolving Xcode 15 device connection issues documents the SIOCGIFDIRECTLINK flag as a specific way to identify the network interfaces uses by Xcode for device connection traffic. Revision History 2025-12-10 Added info about SIOCGIFDIRECTLINK. 2023-07-19 First posted.