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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

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DNS updates and Apple Private Relay - major issue
After dropping an A-record TTL to 60 secs (it was previously no higher than 600 secs for several weeks) and making an IP change for a small business website on Monday, I took down the old web service just over 24 hours later on Tuesday evening. We then had reports of some customers not being able to access the website on Wednesday morning. On investigation using my iPhone it would appear that Apple Private Relay is still directing clients to the old IP address. It's just as well I have iCloud+ as I would never have seen this issue otherwise and would have been none the wiser as to why some customers were having problems. Has anyone else seen this and/or have a fix other than waiting longer? Do you know how long it takes for Apple Private Relay to update? This isn't expected behaviour of DNS? I spoke to someone at Apple yesterday and there wasn't much they can do. I hope they're escalating internally as almost 3 days later it's still pointing users to the old IP address despite having ample time for proper DNS propagation.
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195
Nov ’25
App Outgoing Internet Connections are Blocked
I am trying to activate an application which sends my serial number to a server. The send is being blocked. The app is signed but not sandboxed. I am running Sequoia on a recent iMac. My network firewall is off and I do not have any third party virus software. I have selected Allow Applications from App Store & Known Developers. My local network is wifi using the eero product. There is no firewall or virus scanning installed with this product. Under what circumstances will Mac OS block outgoing internet connections from a non-sandboxed app? How else could the outgoing connection be blocked?
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268
Jun ’25
Intercept local connections with NETransparentProxyProvider
I am trying to intercept localhost connections within NETransparentProxyProvider system extension. As per NENetworkRule documentation If the address is a wildcard address (0.0.0.0 or ::) then the rule will match all destinations except for loopback (127.0.0.1 or ::1). To match loopback traffic set the address to the loopback address. I tried to add NWHostEndpoint *localhostv4 = [NWHostEndpoint endpointWithHostname:@"127.0.0.1" port:@""]; NENetworkRule *localhostv4Rule = [[NENetworkRule alloc] initWithDestinationNetwork:localhostv4 prefix:32 protocol:NENetworkRuleProtocolAny]; in the include network rules. I tried several variations of this rule like port 0, prefix 0 and some others. But the provider disregards the rule and the never receives any traffic going to localhost on any port. Is there any other configuration required to receive localhost traffic in NETransparentProxyProvider?
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189
Jul ’25
AccessorySetupKit / Wi-Fi Aware example?
Greetings, According to Apple's Wi-Fi Aware documentation (https://developer.apple.com/documentation/wifiaware) the Wi-Fi Aware APIs can be used only with peer devices that have been paired. Pairing can be performed using AccessorySetupKit or DeviceDiscoveryUI. Unfortunately, the sample code for Wi-Fi Aware doesn't include either of these APIs. (https://developer.apple.com/documentation/wifiaware/building-peer-to-peer-apps) Looking at the sample code for AccessorySetupKit (https://developer.apple.com/documentation/accessorysetupkit/setting-up-and-authorizing-a-bluetooth-accessory) there is only an example using Bluetooth. And the AccessorySetupKit APIs don't yet document how Wi-Fi Aware is used or how one sets up the Info.plist with the appropriate keys. Can Apple update its example code to fill in these gaps or point me to documentation that can fill in these gaps? It is hard to develop an understanding of the capabilities of these APIs when they are so poorly documented. Thanks for any help, Smith
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258
Feb ’26
NFC Missing required entitlement
Hi, I have created an application for NFC tag scanning and read the tag data. For that, i enabled the capability: NearField Communication Tag reading. Then I added 2 tag formats in the entitlement then i added info.plist: NFCReaderUsageDescription We need to use NFC com.apple.developer.nfc.readersession.felica.systemcodes 8005 8008 0003 fe00 90b7 927a 12FC 86a7 com.apple.developer.nfc.readersession.iso7816.select-identifiers D2760000850100 D2760000850101 but even though when i run the app and tap the nfc card im getting some error: NFCTag didBecomeActive 2025-08-29 19:08:12.272278+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.282869+0530 SAFRAN_NFC[894:113520] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.284044+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.372116+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.381535+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.382246+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.470667+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.479336+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.480101+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling Could you please help me wha tis the issue and give solution for that?
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243
Aug ’25
On FTP
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.
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5.9k
Oct ’25
iOS Network Signal Strength
This issue has cropped up many times here on DevForums. Someone recently opened a DTS tech support incident about it, and I used that as an opportunity to post a definitive response here. If you have questions or comments about this, start a new thread and tag it with Network so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" iOS Network Signal Strength The iOS SDK has no general-purpose API that returns Wi-Fi or cellular signal strength in real time. Given that this has been the case for more than 10 years, it’s safe to assume that it’s not an accidental omission but a deliberate design choice. For information about the Wi-Fi APIs that are available on iOS, see TN3111 iOS Wi-Fi API overview. Network performance Most folks who ask about this are trying to use the signal strength to estimate network performance. This is a technique that I specifically recommend against. That’s because it produces both false positives and false negatives: The network signal might be weak and yet your app has excellent connectivity. For example, an iOS device on stage at WWDC might have terrible WWAN and Wi-Fi signal but that doesn’t matter because it’s connected to the Ethernet. The network signal might be strong and yet your app has very poor connectivity. For example, if you’re on a train, Wi-Fi signal might be strong in each carriage but the overall connection to the Internet is poor because it’s provided by a single over-stretched WWAN. The only good way to determine whether connectivity is good is to run a network request and see how it performs. If you’re issuing a lot of requests, use the performance of those requests to build a running estimate of how well the network is doing. Indeed, Apple practices what we preach here: This is exactly how HTTP Live Streaming works. Remember that network performance can change from moment to moment. The user’s train might enter or leave a tunnel, the user might step into a lift, and so on. If you build code to estimate the network performance, make sure it reacts to such changes. Keeping all of the above in mind, iOS 26 beta has two new APIs related to this issue: Network framework now offers a linkQuality property. See this post for my take on how to use this effectively. The WirelessInsights framework can notify you of anticipated WWAN condition changes. But what about this code I found on the ’net? Over the years various folks have used various unsupported techniques to get around this limitation. If you find code on the ’net that, say, uses KVC to read undocumented properties, or grovels through system logs, or walks the view hierarchy of the status bar, don’t use it. Such techniques are unsupported and, assuming they haven’t broken yet, are likely to break in the future. But what about Hotspot Helper? Hotspot Helper does have an API to read Wi-Fi signal strength, namely, the signalStrength property. However, this is not a general-purpose API. Like the rest of Hotspot Helper, this is tied to the specific use case for which it was designed. This value only updates in real time for networks that your hotspot helper is managing, as indicated by the isChosenHelper property. But what about MetricKit? MetricKit is so cool. Amongst other things, it supports the MXCellularConditionMetric payload, which holds a summary of the cellular conditions while your app was running. However, this is not a real-time signal strength value. But what if I’m working for a carrier? This post is about APIs in the iOS SDK. If you’re working for a carrier, discuss your requirements with your carrier’s contact at Apple. Revision History 2025-07-02 Updated to cover new features in the iOS 16 beta. Made other minor editorial changes. 2022-12-01 First posted.
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4.6k
Jul ’25
Question Regarding peekOutboundBytes Limit in NEFilterDataProvider When Using SMB
Dear Apple Developer Technical Support, I am currently developing a macOS network filtering solution using NetworkExtension with NEFilterDataProvider. During implementation of the handleOutboundData logic, we are using the following verdict: NEFilterNewFlowVerdict.filterDataVerdict( withFilterInbound: true, peekInboundBytes: InboundPeekBytes, filterOutbound: true, peekOutboundBytes: OutboundPeekBytes ) However, we have encountered an issue when SMB traffic is involved. When SMB protocol communication occurs, the network connection occasionally becomes unresponsive or appears to stall when peekOutboundBytes is set to a large value. Through testing, we observed the following behavior: On some systems, reducing the peekOutboundBytes value allows SMB communication to proceed normally. On other systems, even relatively small values can still cause the SMB connection to stall. This behavior appears inconsistent across different macOS environments. Because of this, we would like to clarify the following: Is there a documented or recommended maximum value for peekOutboundBytes when using NEFilterNewFlowVerdict.filterDataVerdict? Are there any internal limits or constraints within NetworkExtension that could cause SMB traffic to stall when the peek buffer size is too large? Are there best practices for selecting appropriate peekInboundBytes / peekOutboundBytes values when filtering high-throughput protocols such as SMB? If necessary, we can provide additional information such as macOS version, test environment details, and logs. Thank you for your assistance. Best regards, sangho
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81
Feb ’26
Video AirPlay from iOS to tvOS doesn't work with VPN on when enforceRoutes is enabled
Hey! We discovered an unexpected side-effect of enabling enforceRoutes in our iOS VPN application - video airplay from iOS to tvOS stopped working (Unable to Connect popup appears instead). Our flags combination is: includeAllNetworks = false enforceRoutes = true excludeLocalNetworks = true Interestingly, music content can be AirPlayed with the same conditions. Also, video AirPlay from iOS device to the macOS works flawlessly. Do you know if this is a known issue? Do you have any advice if we can fix this problem on our side, while keeping enforcRoutes flag enabled?
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124
Mar ’26
Need Help with TUN Writeback
Hi everyone, I'm currently experimenting with building a simple DNS filter using Apple's Packet Tunnel framework. Here's the flow I'm trying to implement: Create a TUN interface Set up a UDP socket Read packets via packetFlow.readPackets Parse the raw IP packet Forward the UDP payload through the socket Receive the response from the server Reconstruct the IP packet with the response Write it back to the TUN interface using packetFlow.writePackets Here’s an example of an intercepted IP packet (DNS request): 45 00 00 3c 15 c4 00 00 40 11 93 d1 c0 a8 00 64 08 08 08 08 ed 6e 00 35 00 28 e5 c9 7f da 01 00 00 01 00 00 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 And here’s the IP packet I tried writing back into the TUN interface (DNS response): 45 00 00 89 5e 37 40 00 40 11 0b 11 08 08 08 08 c0 a8 00 64 00 35 ed 6e 00 75 91 e8 7f da 81 80 00 01 00 04 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 c0 0c 00 05 00 01 00 00 0c fb 00 11 04 74 69 6d 65 01 67 07 61 61 70 6c 69 6d 67 c0 17 c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 fd c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 7d c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 54 fb Unfortunately, it seems the packet is not being written back correctly to the TUN interface. I'm not seeing any expected DNS response behavior on the device. Also, I noticed that after creating the TUN, the interface address shows up as 0.0.0.0:0 in Xcode. The system log includes this message when connecting the VPN: NWPath does not have valid interface: satisfied (Path is satisfied), interface: utun20[endc_sub6], ipv4, dns, expensive, uses cellular Does anyone know how to properly initialize the TUN so that the system recognizes it with a valid IP configuration? Or why my written-back packet might be getting ignored? Any help would be appreciated!
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106
Jul ’25
Background UDP receive for lighting control (Art-Net/sACN)
I'm developing a lighting control app for iOS that receives Art-Net (UDP port 6454) and sACN (UDP port 5568) packets from a lighting console and relays commands to BLE wristbands with LEDs. This is used in live event production — the participant locks their phone while in a show and expects lighting control to continue uninterrupted. The problem UDP receive stops reliably ~30 seconds after the screen locks. I understand this is by design - iOS suspends apps in the background. However, I'm trying to understand if any supported path exists for this use case. What I've already tried UIRequiresPersistentWiFi = true - helps with Wi-Fi association but doesn't prevent app suspension Silent AVAudioEngine loop with UIBackgroundModes: audio - keeps the app alive, works in testing, but risks App Store rejection and feels like an abuse of the audio background mode NWListener (Network framework) on the UDP port - same suspension behaviour Socket rebind on applicationWillEnterForeground - recovers after resume but doesn't prevent dropout What I'm asking Is there any supported background mode or entitlement for sustained UDP receive in a professional/enterprise context? (Similar to how VoIP apps get the voip background mode for sustained network activity.) Is the silent audio workaround considered acceptable for App Store distribution in a professional tools context, or will it be rejected? Is NEAppProxyProvider or another Network Extension a viable path, and if so does it require a special entitlement? Test project I have a minimal Xcode project (~130 lines) demonstrating the issue — NWListener on port 6454, packet counter, staleness timer, and silent audio toggle. I can share the test code. STEPS TO REPRODUCE In Xcode (one-time setup): Select the UDPBackgroundTest target → Signing & Capabilities → set your Team Plug in your iPhone → select it as the run destination Build & run — confirm packets appear on screen when you run 'send_test_udp.py' Lock the phone and observe the dropout Test: Open the app and run 'python3 send_test_udp.py 192.168.0.XXX' The app counts up the packages, they match the python output. 1 packet per second. lock screen & and wait 10 seconds unlock phone an see the numbers are 10 packets off
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87
Apr ’26
How to delete cookies on IOS18
Hello, I have encountered an issue with an iPhone 15PM with iOS 18.5. The NSHTTPCookieStorage failed to clear cookies, but even after clearing them, I was still able to retrieve them. However, on the same system It is normal on iPhone 14PM. I would like to know the specific reason and whether there are any adaptation related issues. Following code: NSHTTPCookie *cookie; NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage]; for (cookie in [storage cookies]) { [storage deleteCookie:cookie]; }
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183
May ’25
NETransparentProxyProvider frequent tunnel churn during Dark Wake cycles on macOS.
Description Our NETransparentProxyProvider system extension maintains a persistent TLS/DTLS control channel to a security gateway. To maintain this stateful connection the extension sends application-level "Keep Alive" packets every few seconds (example : 20 seconds). The Issue: When the macOS device enters a sleep state, the Network Extension process is suspended, causing our application-level heartbeat to cease. Consequently, our backend gateway—detecting no activity—terminates the session via Dead Peer Detection (DPD). The problem is exacerbated by macOS Dark Wake cycles. We observe the extension's wake() callback being triggered periodically (approx. every 15 minutes) while the device remains in a sleep state (lid closed). During these brief windows: The extension attempts to use the existing socket, finds it terminated by the backend, and initiates a full re-handshake. Shortly after the connection is re-established, the OS triggers the sleep() callback and suspends the process again. This creates a "connection churn" cycle that generates excessive telemetry noise and misleading "Session Disconnected" alerts for our enterprise customers. Steps to Reproduce Activate Proxy: Start the NETransparentProxyProvider and establish a TLS session to a gateway. Apply Settings: Configure NETransparentProxyNetworkSettings to intercept outbound TCP/UDP traffic. Initialize Heartbeat: Start a 20-second timer (DispatchSourceTimer) to log and send keep-alive packets. Induce Sleep: Put the Mac to sleep (Apple Menu > Sleep). Observe Logs: Monitor the system via sysdiagnose or the macOS Console. Observation: Logs stop entirely during sleep, indicating process suspension. Observation: wake() and sleep() callbacks are triggered repeatedly during Dark Wake intervals, causing a cycle of re-connections. Expected Behavior We seek to minimize connection turnover during maintenance wakes and maintain session stability while the device is technically in a sleep state. Questions for Apple Is it possible to suppress the sleep and wake callback methods of NETransparentProxyProvider when the device is performing a maintenance/Dark Wake, only triggering them for a full user-initiated wake? Is it possible to prevent the NETransparentProxyProvider process from being suspended during sleep, or at least grant it a high-priority background execution slot to maintain the heartbeat? If suspension is mandatory, is there a recommended way to utilize TCP_KEEPALIVE socket options that the kernel can handle on behalf of the suspended extension? How can the extension programmatically identify if a wake() call is a "Dark Wake" versus a "Full User Wake" to avoid unnecessary re-connection logic?
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181
Feb ’26
NWEndpoint History and Advice
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.
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304
Jul ’25
M5 kernel panic skmem_slab_free_locked in the presence of a network system extension
I've seen a number of similar posts from other network system extension developers reporting kernel panics on M5 devices in macOS. These kernel panics occur when network system extensions are enabled and are not observed on earlier mac platforms or versions of macOS. Reference: https://developer.apple.com/forums/thread/821372 In this post, it appears like Apple is aware of a problem as noted by Kevin Elliott in versions of macOS. Do we know if there is any way to work around this problem (short of not enabling a network filter) until a fix is available?
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5d
Matter OTA on TestNet: HomePod always replies "UpdateNotAvailable" (Device is already CSA Certified)
Hi Apple Team / Community, We are currently pulling our hair out over a TestNet OTA issue and could really use some help. Our Matter Door Lock (VID: 5424, PID: 513) has already obtained official CSA Certification, so we are 100% confident that our device firmware and OTA Requestor logic are completely solid. However, we simply cannot get Apple's TestNet to serve the update via HomePod. Here is exactly what is happening: Our device successfully sends a QueryImage command to the HomePod. The HomePod receives it, but immediately fires back a QueryImageResponse that essentially means "UpdateNotAvailable", forcing the device into an 86400-second sleep timeout. Here is what we have verified so far: Local OTA works perfectly: If we use Nordic's chip-ota-provider-app locally with the exact same .ota file, the BDX transfer triggers instantly and the device updates without a hitch. DCL details are 100% accurate: We published a brand new version (1.0.4 / 16778240) which is strictly higher than the device's current version (1.0.1 / 16777472). The otaFileSize (973839) and Base64 Checksum match the file perfectly. ZERO hits on our server: The OTA file is hosted on an AWS S3 direct link (SSL Grade A via SSL Labs, ATS compliant). We checked our server logs, and there hasn't been a single download attempt from any Apple IP addresses. Since our device is certified and local OTA works flawlessly, it strongly feels like Apple's TestNet backend either has a stuck/cached "invalid" state for our VID/PID (very similar to what was reported in CHIP GitHub Issue #29338), or the Apple backend crawler is failing to reach our URL for some internal reason. Could someone please check if there is a cached exception for VID: 5424 / PID: 513 on the TestNet backend? Any help or pointers would be hugely appreciated! Thanks in advance.
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Mar ’26
Does app launch recency affect NEPacketTunnelProvider, HotspotHelper, or NEHotspotManager functionality?
We are assisting a client with their app integration. The client believes that NEPacketTunnelProvider, NEHotspotHelper, and NEHotspotManager extensions stop functioning if the containing app hasn't been launched by the user within some recent window (e.g. 30, 60, or 90 days). We haven't been able to find any documentation supporting this claim. Specifically, we'd like to know: Is there any app launch recency requirement that would cause iOS to stop invoking a registered NEHotspotHelper or NEHotspotManager configuration? Is there any app launch recency requirement that would cause iOS to tear down or prevent activation of a NEPacketTunnelProvider? More generally, does iOS enforce any kind of "staleness" check on apps that provide Network Extension or Hotspot-related functionality, where not being foregrounded for some period causes the system to stop honoring their registrations? If such a mechanism exists, we'd appreciate any pointers to documentation or technical notes describing the behavior and timeframes involved. If it doesn't exist, confirmation would help us guide our client's debugging in the right direction. Thank you.
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Mar ’26
DNS updates and Apple Private Relay - major issue
After dropping an A-record TTL to 60 secs (it was previously no higher than 600 secs for several weeks) and making an IP change for a small business website on Monday, I took down the old web service just over 24 hours later on Tuesday evening. We then had reports of some customers not being able to access the website on Wednesday morning. On investigation using my iPhone it would appear that Apple Private Relay is still directing clients to the old IP address. It's just as well I have iCloud+ as I would never have seen this issue otherwise and would have been none the wiser as to why some customers were having problems. Has anyone else seen this and/or have a fix other than waiting longer? Do you know how long it takes for Apple Private Relay to update? This isn't expected behaviour of DNS? I spoke to someone at Apple yesterday and there wasn't much they can do. I hope they're escalating internally as almost 3 days later it's still pointing users to the old IP address despite having ample time for proper DNS propagation.
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195
Activity
Nov ’25
App Outgoing Internet Connections are Blocked
I am trying to activate an application which sends my serial number to a server. The send is being blocked. The app is signed but not sandboxed. I am running Sequoia on a recent iMac. My network firewall is off and I do not have any third party virus software. I have selected Allow Applications from App Store & Known Developers. My local network is wifi using the eero product. There is no firewall or virus scanning installed with this product. Under what circumstances will Mac OS block outgoing internet connections from a non-sandboxed app? How else could the outgoing connection be blocked?
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268
Activity
Jun ’25
-10985 network error from urlSession
Getting -10985 error from urlSession while attempting to make a connection. Not sure why this is happening if anyone is aware please help
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231
Activity
Nov ’25
How long will it take to receive multicast entitlement approval?
Hello all, Does anyone know how long it will take Apple to approve multicast entitlement approval after the Apple form is submitted? Any input would be appreciated. Thank you Allyson
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599
Activity
Jun ’25
Intercept local connections with NETransparentProxyProvider
I am trying to intercept localhost connections within NETransparentProxyProvider system extension. As per NENetworkRule documentation If the address is a wildcard address (0.0.0.0 or ::) then the rule will match all destinations except for loopback (127.0.0.1 or ::1). To match loopback traffic set the address to the loopback address. I tried to add NWHostEndpoint *localhostv4 = [NWHostEndpoint endpointWithHostname:@"127.0.0.1" port:@""]; NENetworkRule *localhostv4Rule = [[NENetworkRule alloc] initWithDestinationNetwork:localhostv4 prefix:32 protocol:NENetworkRuleProtocolAny]; in the include network rules. I tried several variations of this rule like port 0, prefix 0 and some others. But the provider disregards the rule and the never receives any traffic going to localhost on any port. Is there any other configuration required to receive localhost traffic in NETransparentProxyProvider?
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189
Activity
Jul ’25
AccessorySetupKit / Wi-Fi Aware example?
Greetings, According to Apple's Wi-Fi Aware documentation (https://developer.apple.com/documentation/wifiaware) the Wi-Fi Aware APIs can be used only with peer devices that have been paired. Pairing can be performed using AccessorySetupKit or DeviceDiscoveryUI. Unfortunately, the sample code for Wi-Fi Aware doesn't include either of these APIs. (https://developer.apple.com/documentation/wifiaware/building-peer-to-peer-apps) Looking at the sample code for AccessorySetupKit (https://developer.apple.com/documentation/accessorysetupkit/setting-up-and-authorizing-a-bluetooth-accessory) there is only an example using Bluetooth. And the AccessorySetupKit APIs don't yet document how Wi-Fi Aware is used or how one sets up the Info.plist with the appropriate keys. Can Apple update its example code to fill in these gaps or point me to documentation that can fill in these gaps? It is hard to develop an understanding of the capabilities of these APIs when they are so poorly documented. Thanks for any help, Smith
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258
Activity
Feb ’26
NFC Missing required entitlement
Hi, I have created an application for NFC tag scanning and read the tag data. For that, i enabled the capability: NearField Communication Tag reading. Then I added 2 tag formats in the entitlement then i added info.plist: NFCReaderUsageDescription We need to use NFC com.apple.developer.nfc.readersession.felica.systemcodes 8005 8008 0003 fe00 90b7 927a 12FC 86a7 com.apple.developer.nfc.readersession.iso7816.select-identifiers D2760000850100 D2760000850101 but even though when i run the app and tap the nfc card im getting some error: NFCTag didBecomeActive 2025-08-29 19:08:12.272278+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.282869+0530 SAFRAN_NFC[894:113520] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.284044+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.372116+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.381535+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.382246+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.470667+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.479336+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.480101+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling Could you please help me wha tis the issue and give solution for that?
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243
Activity
Aug ’25
On FTP
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.
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5.9k
Activity
Oct ’25
iOS Network Signal Strength
This issue has cropped up many times here on DevForums. Someone recently opened a DTS tech support incident about it, and I used that as an opportunity to post a definitive response here. If you have questions or comments about this, start a new thread and tag it with Network so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" iOS Network Signal Strength The iOS SDK has no general-purpose API that returns Wi-Fi or cellular signal strength in real time. Given that this has been the case for more than 10 years, it’s safe to assume that it’s not an accidental omission but a deliberate design choice. For information about the Wi-Fi APIs that are available on iOS, see TN3111 iOS Wi-Fi API overview. Network performance Most folks who ask about this are trying to use the signal strength to estimate network performance. This is a technique that I specifically recommend against. That’s because it produces both false positives and false negatives: The network signal might be weak and yet your app has excellent connectivity. For example, an iOS device on stage at WWDC might have terrible WWAN and Wi-Fi signal but that doesn’t matter because it’s connected to the Ethernet. The network signal might be strong and yet your app has very poor connectivity. For example, if you’re on a train, Wi-Fi signal might be strong in each carriage but the overall connection to the Internet is poor because it’s provided by a single over-stretched WWAN. The only good way to determine whether connectivity is good is to run a network request and see how it performs. If you’re issuing a lot of requests, use the performance of those requests to build a running estimate of how well the network is doing. Indeed, Apple practices what we preach here: This is exactly how HTTP Live Streaming works. Remember that network performance can change from moment to moment. The user’s train might enter or leave a tunnel, the user might step into a lift, and so on. If you build code to estimate the network performance, make sure it reacts to such changes. Keeping all of the above in mind, iOS 26 beta has two new APIs related to this issue: Network framework now offers a linkQuality property. See this post for my take on how to use this effectively. The WirelessInsights framework can notify you of anticipated WWAN condition changes. But what about this code I found on the ’net? Over the years various folks have used various unsupported techniques to get around this limitation. If you find code on the ’net that, say, uses KVC to read undocumented properties, or grovels through system logs, or walks the view hierarchy of the status bar, don’t use it. Such techniques are unsupported and, assuming they haven’t broken yet, are likely to break in the future. But what about Hotspot Helper? Hotspot Helper does have an API to read Wi-Fi signal strength, namely, the signalStrength property. However, this is not a general-purpose API. Like the rest of Hotspot Helper, this is tied to the specific use case for which it was designed. This value only updates in real time for networks that your hotspot helper is managing, as indicated by the isChosenHelper property. But what about MetricKit? MetricKit is so cool. Amongst other things, it supports the MXCellularConditionMetric payload, which holds a summary of the cellular conditions while your app was running. However, this is not a real-time signal strength value. But what if I’m working for a carrier? This post is about APIs in the iOS SDK. If you’re working for a carrier, discuss your requirements with your carrier’s contact at Apple. Revision History 2025-07-02 Updated to cover new features in the iOS 16 beta. Made other minor editorial changes. 2022-12-01 First posted.
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4.6k
Activity
Jul ’25
Question Regarding peekOutboundBytes Limit in NEFilterDataProvider When Using SMB
Dear Apple Developer Technical Support, I am currently developing a macOS network filtering solution using NetworkExtension with NEFilterDataProvider. During implementation of the handleOutboundData logic, we are using the following verdict: NEFilterNewFlowVerdict.filterDataVerdict( withFilterInbound: true, peekInboundBytes: InboundPeekBytes, filterOutbound: true, peekOutboundBytes: OutboundPeekBytes ) However, we have encountered an issue when SMB traffic is involved. When SMB protocol communication occurs, the network connection occasionally becomes unresponsive or appears to stall when peekOutboundBytes is set to a large value. Through testing, we observed the following behavior: On some systems, reducing the peekOutboundBytes value allows SMB communication to proceed normally. On other systems, even relatively small values can still cause the SMB connection to stall. This behavior appears inconsistent across different macOS environments. Because of this, we would like to clarify the following: Is there a documented or recommended maximum value for peekOutboundBytes when using NEFilterNewFlowVerdict.filterDataVerdict? Are there any internal limits or constraints within NetworkExtension that could cause SMB traffic to stall when the peek buffer size is too large? Are there best practices for selecting appropriate peekInboundBytes / peekOutboundBytes values when filtering high-throughput protocols such as SMB? If necessary, we can provide additional information such as macOS version, test environment details, and logs. Thank you for your assistance. Best regards, sangho
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81
Activity
Feb ’26
Video AirPlay from iOS to tvOS doesn't work with VPN on when enforceRoutes is enabled
Hey! We discovered an unexpected side-effect of enabling enforceRoutes in our iOS VPN application - video airplay from iOS to tvOS stopped working (Unable to Connect popup appears instead). Our flags combination is: includeAllNetworks = false enforceRoutes = true excludeLocalNetworks = true Interestingly, music content can be AirPlayed with the same conditions. Also, video AirPlay from iOS device to the macOS works flawlessly. Do you know if this is a known issue? Do you have any advice if we can fix this problem on our side, while keeping enforcRoutes flag enabled?
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124
Activity
Mar ’26
Need Help with TUN Writeback
Hi everyone, I'm currently experimenting with building a simple DNS filter using Apple's Packet Tunnel framework. Here's the flow I'm trying to implement: Create a TUN interface Set up a UDP socket Read packets via packetFlow.readPackets Parse the raw IP packet Forward the UDP payload through the socket Receive the response from the server Reconstruct the IP packet with the response Write it back to the TUN interface using packetFlow.writePackets Here’s an example of an intercepted IP packet (DNS request): 45 00 00 3c 15 c4 00 00 40 11 93 d1 c0 a8 00 64 08 08 08 08 ed 6e 00 35 00 28 e5 c9 7f da 01 00 00 01 00 00 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 And here’s the IP packet I tried writing back into the TUN interface (DNS response): 45 00 00 89 5e 37 40 00 40 11 0b 11 08 08 08 08 c0 a8 00 64 00 35 ed 6e 00 75 91 e8 7f da 81 80 00 01 00 04 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 c0 0c 00 05 00 01 00 00 0c fb 00 11 04 74 69 6d 65 01 67 07 61 61 70 6c 69 6d 67 c0 17 c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 fd c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 7d c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 54 fb Unfortunately, it seems the packet is not being written back correctly to the TUN interface. I'm not seeing any expected DNS response behavior on the device. Also, I noticed that after creating the TUN, the interface address shows up as 0.0.0.0:0 in Xcode. The system log includes this message when connecting the VPN: NWPath does not have valid interface: satisfied (Path is satisfied), interface: utun20[endc_sub6], ipv4, dns, expensive, uses cellular Does anyone know how to properly initialize the TUN so that the system recognizes it with a valid IP configuration? Or why my written-back packet might be getting ignored? Any help would be appreciated!
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106
Activity
Jul ’25
Background UDP receive for lighting control (Art-Net/sACN)
I'm developing a lighting control app for iOS that receives Art-Net (UDP port 6454) and sACN (UDP port 5568) packets from a lighting console and relays commands to BLE wristbands with LEDs. This is used in live event production — the participant locks their phone while in a show and expects lighting control to continue uninterrupted. The problem UDP receive stops reliably ~30 seconds after the screen locks. I understand this is by design - iOS suspends apps in the background. However, I'm trying to understand if any supported path exists for this use case. What I've already tried UIRequiresPersistentWiFi = true - helps with Wi-Fi association but doesn't prevent app suspension Silent AVAudioEngine loop with UIBackgroundModes: audio - keeps the app alive, works in testing, but risks App Store rejection and feels like an abuse of the audio background mode NWListener (Network framework) on the UDP port - same suspension behaviour Socket rebind on applicationWillEnterForeground - recovers after resume but doesn't prevent dropout What I'm asking Is there any supported background mode or entitlement for sustained UDP receive in a professional/enterprise context? (Similar to how VoIP apps get the voip background mode for sustained network activity.) Is the silent audio workaround considered acceptable for App Store distribution in a professional tools context, or will it be rejected? Is NEAppProxyProvider or another Network Extension a viable path, and if so does it require a special entitlement? Test project I have a minimal Xcode project (~130 lines) demonstrating the issue — NWListener on port 6454, packet counter, staleness timer, and silent audio toggle. I can share the test code. STEPS TO REPRODUCE In Xcode (one-time setup): Select the UDPBackgroundTest target → Signing & Capabilities → set your Team Plug in your iPhone → select it as the run destination Build & run — confirm packets appear on screen when you run 'send_test_udp.py' Lock the phone and observe the dropout Test: Open the app and run 'python3 send_test_udp.py 192.168.0.XXX' The app counts up the packages, they match the python output. 1 packet per second. lock screen & and wait 10 seconds unlock phone an see the numbers are 10 packets off
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87
Activity
Apr ’26
Wi-Fi MAC address information
Have you ever encountered the issue where the Wi-Fi MAC address information can no longer be retrieved after I updated to iOS 26?
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169
Activity
Feb ’26
How to delete cookies on IOS18
Hello, I have encountered an issue with an iPhone 15PM with iOS 18.5. The NSHTTPCookieStorage failed to clear cookies, but even after clearing them, I was still able to retrieve them. However, on the same system It is normal on iPhone 14PM. I would like to know the specific reason and whether there are any adaptation related issues. Following code: NSHTTPCookie *cookie; NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage]; for (cookie in [storage cookies]) { [storage deleteCookie:cookie]; }
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183
Activity
May ’25
NETransparentProxyProvider frequent tunnel churn during Dark Wake cycles on macOS.
Description Our NETransparentProxyProvider system extension maintains a persistent TLS/DTLS control channel to a security gateway. To maintain this stateful connection the extension sends application-level "Keep Alive" packets every few seconds (example : 20 seconds). The Issue: When the macOS device enters a sleep state, the Network Extension process is suspended, causing our application-level heartbeat to cease. Consequently, our backend gateway—detecting no activity—terminates the session via Dead Peer Detection (DPD). The problem is exacerbated by macOS Dark Wake cycles. We observe the extension's wake() callback being triggered periodically (approx. every 15 minutes) while the device remains in a sleep state (lid closed). During these brief windows: The extension attempts to use the existing socket, finds it terminated by the backend, and initiates a full re-handshake. Shortly after the connection is re-established, the OS triggers the sleep() callback and suspends the process again. This creates a "connection churn" cycle that generates excessive telemetry noise and misleading "Session Disconnected" alerts for our enterprise customers. Steps to Reproduce Activate Proxy: Start the NETransparentProxyProvider and establish a TLS session to a gateway. Apply Settings: Configure NETransparentProxyNetworkSettings to intercept outbound TCP/UDP traffic. Initialize Heartbeat: Start a 20-second timer (DispatchSourceTimer) to log and send keep-alive packets. Induce Sleep: Put the Mac to sleep (Apple Menu > Sleep). Observe Logs: Monitor the system via sysdiagnose or the macOS Console. Observation: Logs stop entirely during sleep, indicating process suspension. Observation: wake() and sleep() callbacks are triggered repeatedly during Dark Wake intervals, causing a cycle of re-connections. Expected Behavior We seek to minimize connection turnover during maintenance wakes and maintain session stability while the device is technically in a sleep state. Questions for Apple Is it possible to suppress the sleep and wake callback methods of NETransparentProxyProvider when the device is performing a maintenance/Dark Wake, only triggering them for a full user-initiated wake? Is it possible to prevent the NETransparentProxyProvider process from being suspended during sleep, or at least grant it a high-priority background execution slot to maintain the heartbeat? If suspension is mandatory, is there a recommended way to utilize TCP_KEEPALIVE socket options that the kernel can handle on behalf of the suspended extension? How can the extension programmatically identify if a wake() call is a "Dark Wake" versus a "Full User Wake" to avoid unnecessary re-connection logic?
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Feb ’26
NWEndpoint History and Advice
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.
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Activity
Jul ’25
M5 kernel panic skmem_slab_free_locked in the presence of a network system extension
I've seen a number of similar posts from other network system extension developers reporting kernel panics on M5 devices in macOS. These kernel panics occur when network system extensions are enabled and are not observed on earlier mac platforms or versions of macOS. Reference: https://developer.apple.com/forums/thread/821372 In this post, it appears like Apple is aware of a problem as noted by Kevin Elliott in versions of macOS. Do we know if there is any way to work around this problem (short of not enabling a network filter) until a fix is available?
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5d
Matter OTA on TestNet: HomePod always replies "UpdateNotAvailable" (Device is already CSA Certified)
Hi Apple Team / Community, We are currently pulling our hair out over a TestNet OTA issue and could really use some help. Our Matter Door Lock (VID: 5424, PID: 513) has already obtained official CSA Certification, so we are 100% confident that our device firmware and OTA Requestor logic are completely solid. However, we simply cannot get Apple's TestNet to serve the update via HomePod. Here is exactly what is happening: Our device successfully sends a QueryImage command to the HomePod. The HomePod receives it, but immediately fires back a QueryImageResponse that essentially means "UpdateNotAvailable", forcing the device into an 86400-second sleep timeout. Here is what we have verified so far: Local OTA works perfectly: If we use Nordic's chip-ota-provider-app locally with the exact same .ota file, the BDX transfer triggers instantly and the device updates without a hitch. DCL details are 100% accurate: We published a brand new version (1.0.4 / 16778240) which is strictly higher than the device's current version (1.0.1 / 16777472). The otaFileSize (973839) and Base64 Checksum match the file perfectly. ZERO hits on our server: The OTA file is hosted on an AWS S3 direct link (SSL Grade A via SSL Labs, ATS compliant). We checked our server logs, and there hasn't been a single download attempt from any Apple IP addresses. Since our device is certified and local OTA works flawlessly, it strongly feels like Apple's TestNet backend either has a stuck/cached "invalid" state for our VID/PID (very similar to what was reported in CHIP GitHub Issue #29338), or the Apple backend crawler is failing to reach our URL for some internal reason. Could someone please check if there is a cached exception for VID: 5424 / PID: 513 on the TestNet backend? Any help or pointers would be hugely appreciated! Thanks in advance.
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Activity
Mar ’26
Does app launch recency affect NEPacketTunnelProvider, HotspotHelper, or NEHotspotManager functionality?
We are assisting a client with their app integration. The client believes that NEPacketTunnelProvider, NEHotspotHelper, and NEHotspotManager extensions stop functioning if the containing app hasn't been launched by the user within some recent window (e.g. 30, 60, or 90 days). We haven't been able to find any documentation supporting this claim. Specifically, we'd like to know: Is there any app launch recency requirement that would cause iOS to stop invoking a registered NEHotspotHelper or NEHotspotManager configuration? Is there any app launch recency requirement that would cause iOS to tear down or prevent activation of a NEPacketTunnelProvider? More generally, does iOS enforce any kind of "staleness" check on apps that provide Network Extension or Hotspot-related functionality, where not being foregrounded for some period causes the system to stop honoring their registrations? If such a mechanism exists, we'd appreciate any pointers to documentation or technical notes describing the behavior and timeframes involved. If it doesn't exist, confirmation would help us guide our client's debugging in the right direction. Thank you.
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Mar ’26