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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.

Networking Documentation

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First update to NWBrowser is always ready, irrespective of Local Networking privacy status
I'm trying to detect the state of Local Network privacy on macOS Sequoia via NWBrowser, as recommended in https://developer.apple.com/documentation/technotes/tn3179-understanding-local-network-privacy Regardless of the state of Local Network privacy - undetermined, allowed or denied, NWBrowser receives an update indicating that its in the ready state. Scanning does not seem to trigger the Local Network privacy alert for me - I have to use the other recommended method to trigger the prompt. Enabling or disabling Local Network privacy does not seem to send any updates for NWBrowser. https://developer.apple.com/forums/thread/666431 seems related, and implies that they did receive further updates to NWBrowser. Filed as FB16077972
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Jan ’25
No internet connection on per-app VPN.
I'm developing a per-app VPN iOS app with Wireguard. For that, I created a configuration file with payload type "com.apple.vpn.managed.applayer". Using the MDM server I installed some apps which need to use the VPN connection. But when I open these apps, I could see the VPN getting enabled in the device. The VPN icon appears on the notification bar but no internet connection. The VPN and internet is working correctly if I change the payload type to "com.apple.vpn.managed" in configuration file.
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436
Mar ’25
Getting list of wifi networks nearby with a specific prefix
I'm building an app that helps manage my own wifi access points. Now, all my wifis emit SSIDs starting with the same prefix. Is it possible for me to list down all the SSIDs near me that start with that prefix, so that determine which of my wifis are near me? (Swift) Can NEHotspotHelper or NEHotspotConfigurationManager help in this regard?
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Feb ’25
No internet connection on wireguard per-app vpn in ios
I am integrating per-app VPN functionality into an iOS app using Wireguard. Chrome is designated as a per-app application for this purpose. However, upon opening Chrome, the VPN icon appears in the notification bar, but there is no internet connection within the Chrome browser. I have verified this behavior with OpenVPN, and it works correctly. While I am familiar with the MDM payload and how to implement per-app VPN, my primary concern is understanding why per-app VPN functionality is not functioning as expected with WireGuard. An observation we made in the server-side logs is the message: "wireguard: wg0: Packet has incorrect size from peer 1"
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1.1k
Feb ’25
System Information in macOS 26.2 RC no longer shows Wi-Fi SSIDs
System Information in macOS from 26.0 to 26.2 RC no longer provides Wi-Fi SSIDs; instead, it displays "< redacted> " for every SSID on my two MacBooks. This issue has been fixed in macOS 26.1 beta and macOS 26.2 beta, but it returns in the RC and the Final Release versions. Is it an expected behaviour or a bug in the Release Candidate? MacBook Air 2025: MacBook Pro 2021:
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KeyChain Sharing with App Extensions
Hi, We are trying to use Apple Security API for KeyChain Services. Using the common App Group : Specifying the common app group in the "kSecAttrAccessGroup" field of the KeyChain query, allowed us to have a shared keychains for different apps (targets) in the app group, but this did not work for extensions. Enabling the KeyChain Sharing capability : We enabled the KeyChain Sharing Ability in the extensions and the app target as well, giving a common KeyChain Access group. Specifying this in the kSecAttrAccessGroup field also did not work. This was done in XCode as we were unable to locate it in the Developer portal in Indentifiers. We tried specifying "$AppIdentifier.KeyChainSharingGroup" in the kSecAttrAccessGroup field , but this did not work as well The error code which we get in all these 3 cases when trying to access the Keychain from the extension is error code 25291 (errSecNotAvailable). The Documentation says this error comes when "No Trust Results are available" and printing the error in xcode using the status says "No keychain is available. The online Documentation says that it is possible to share keychain with extensions, but by far we are unable to do it with the methods suggested. Do we need any special entitlement for this or is there something we are missing while using these APIs? We really appreciate any and all help in solving this issue! Thank you
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Local network access is blocked when two almost identical apps are installed
We are developing an enterprise app that connects to a local server. It uses simple URLSessions. There is a view in the app where you enter the server url (IP address) and a connection check is made. iOS asks for permission to access the local network. Everything works. If the server is reachable, the connection info is saved. Recently we encountered a very strange issue: We also have a beta version of this app. If we first install the normal version on a device, enter the server IP, save, and then install the beta version and do the same there: It does not get a connection (it waits for the timeout). The strange part is: If I try to configure the connection in the normal version again, it also does not work, it just waits for the timeout. The really strange part: When I delete the beta version, while the normal version is waiting for its connection, the connection succeeds immediately. Both versions have a different display name, bundle id. I also tried using a device that is not in our MDM: same problem. Even the iOS version seems to have no impact: I tried on iOS 15, 18 and 26. Is there an explanation and hopefully also a solution to this problem?
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Failed to enable the Network Extension
In my application, there is a Network Extension with the bundle ID com.xxx.agent.yyy.zzz.ne. There is a user upgraded their system to macOS Sequoia 15.3, they faced an issue where enabling this Network Extension failed. Even after uninstalling the application and the Network Extension, restarting the system, and reinstalling multiple times, the enabling process still failed. it alert: Failed to enable the Network Extension. When checking the status via "systemextension list", it always shows "activated waiting for user". This shows the normal enabling process log: This shows the log when the enabling fails upon clicking. Strangely enough, there is no activation operation log when it fails. What could be the problem?
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690
Feb ’25
URL filter app with multiple configurations
Hello, We've been working on an app that uses the new NEUrlFilter API and we've got a question. Currently, the system is designed with the assumption that a single app == usecase == single remote database. But what if we would like to give the user the ability to use different blocklists? For example, the user may want to: Block scam domains Block tracking domains Block adult domains Or any composition of these 3 What should we do to give the user this option? It seems that we could differentiate different databases by using different PIR service hostnames, but that would also mean that we'll have to send several requests for the same usecase but with different PIR service hostnames (and they'll all share the same app bundle ID). Will these requests be accepted then? If not, is there an alternative? PS: By sending a request I mean submitting this form
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Oct ’25
Characteristics of a service are lost after successful discovery
My code makes an iPhone use the CBCentralManager to talk to devices peripherals over core bluetooth. After attempting a connect to a peripheral device, I get a didConnect callback on CBCentralManagerDelegate. After this I initiate discovery of services using: peripheral.discoverServices([CBUUID(nsuuid: serviceUUID)]) Since I am only interested in discovering my service of interest and not the others to speed up time to the actual sending of data. This also gives me the didDiscoverServices callback without error prints in which I do the following: guard let services = peripheral.services, !services.isEmpty else { print("Empty services") centralManager.cancelPeripheralConnection(peripheral) return } And for next steps if let serviceOfInterest = services.first(where: {$0.uuid == CBUUID(nsuuid: serviceUUID)}) { //double check for service we want initiateDiscoverCharacteristics(peripheral: peripheral, service: serviceOfInterest) } Below is what initiateDiscoverCharacteristics() does. I basically only tries to discover certain characteristics of the selected service: peripheral.discoverCharacteristics( [CBUUID(nsuuid: readUUID), CBUUID(nsuuid: writeUUID)], for: serviceOfInterest) For this also we get the didDiscoverCharacteristicsFor callback without error prints. Here in this callback however we were not doing the serviceOfInterest check to see that we are getting the callback for the service we expect, since our understanding was that we will get didDiscoverCharacteristicsFor callback for the characteristics on the serviceOfInterest because that is what peripheral.discoverCharacteristics() was initiated for. When we go ahead to write some data/subscribe for notify/read data we have 2 guard statements for services and characteristics of a particular service. The first guard below passes: if(peripheral.services == nil) { print("services yet to be discovered \(peripheral.identifier.uuidString)") return } However the second guard below fails: let serviceOfInterest = peripheral.services?.first(where: {$0.uuid == CBUUID(nsuuid: serviceUUID}) if((serviceOfInterest?.characteristics == nil) || (serviceOfInterest?.characteristics == [])) { print("characteristics yet to be discovered \(peripheral.identifier.uuidString)") return } First of all, does the iPhone go ahead and discover other characteristics and services separately even when we explicitly mention the service and the characteristics it should discover? Now if you say yes and that it maybe the reason of our bug because we didn't do a check for serviceOfInterest in didDiscoverCharacteristicsFor callback, then I have another question. Why don't we get a second/third print in didDiscoverCharacteristicsFor callback signifying that more characteristics were discovered? The peripheral device just disconnects after a set timeout (peripheral device used in our testing does this if we are not communicating with it for a certain amount of time). This issue is extremely rare. We have seen it only twice in our customer base. Both the instances were on the same iPhone 15 Pro. Once a few months back and once recently. Currently, this iPhone is having iOS version 18.1.1 running on it.
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266
Feb ’25
Multipeer Connectivity connection is flaky on iOS 26
While updating our test devices to iOS 26, we noticed that the connection between devices are flaky. Often when connecting to a Peer from a device running iOS 26 we can observe the invite coming through and when accepting said invite, both ends going to .connecting state and a while later going back to .notConnected within the peer(_ peerID: MCPeerID, didChange state: MCSessionState) function. This happens regularly and retrying the invitation process several times usually resolves it. Do anyone have any information or guidance on how to resolve this issue?
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Oct ’25
URLSessionDownloadTaskDelegate functions not called when using URLSession.download(for:), but works when using URLSession.downloadTask(with:)
I'm struggling to understand why the async-await version of URLSession download task APIs do not call the delegate functions, whereas the old non-async version that returns a reference to the download task works just fine. Here is my sample code: class DownloadDelegate: NSObject, URLSessionDownloadDelegate { func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) { // This only prints the percentage of the download progress. let calculatedProgress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite) let formatter = NumberFormatter() formatter.numberStyle = .percent print(formatter.string(from: NSNumber(value: calculatedProgress))!) } } // Here's the VC. final class DownloadsViewController: UIViewController { private let url = URL(string: "https://pixabay.com/get/g0b9fa2936ff6a5078ea607398665e8151fc0c10df7db5c093e543314b883755ecd43eda2b7b5178a7e613a35541be6486885fb4a55d0777ba949aedccc807d8c_1280.jpg")! private let delegate = DownloadDelegate() private lazy var session = URLSession(configuration: .default, delegate: delegate, delegateQueue: nil) // for the async-await version private var task: Task&lt;Void, Never&gt;? // for the old version private var downloadTask: URLSessionDownloadTask? override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) task?.cancel() task = nil task = Task { let (_, _) = try! await session.download(for: URLRequest(url: url)) self.task = nil } // If I uncomment this, the progress listener delegate function above is called. // downloadTask?.cancel() // downloadTask = nil // downloadTask = session.downloadTask(with: URLRequest(url: url)) // downloadTask?.resume() } } What am I missing here?
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May ’25
NEURLFilterManager Error 2 in macOS - How to Validate Configuration Parameters for setConfiguration or saveToPreferences
I'm currently testing URLFilter for use in a macOS product. After calling loadFromPreferences, I set the following configuration parameters: pirServerURL = URL(string: "http://localhost:8080")! pirAuthenticationToken = "AAAA" controlProviderBundleIdentifier = "{extension app bundle identifier}" However, when I call saveToPreferences, I get an Invalid Configuration error. Is there a way to determine which parameter is invalid or incorrectly set? Also, I would appreciate any macOS-specific examples of using NEURLFilterManager, as most of the documentation I’ve found seems to focus on iOS. Thank you.
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Nov ’25
Crash within com.apple.CFNetwork.Connection , specifically due to EXC_BAD_ACCESS KERN_INVALID_ADDRESS.
Crash within com.apple.CFNetwork.Connection , specifically due to EXC_BAD_ACCESS KERN_INVALID_ADDRESS. The crash occurred within the nghttp2_session_del() function indicating a problem with the nghttp2 library, which is commonly used for HTTP/2 communication. This points towards a memory management issue. EXC_BAD_ACCESS generally signifies that the application attempted to access memory it didn't have permission to access, often caused by using a pointer after it has been freed or pointing to an invalid memory address. ** Crashed: com.apple.CFNetwork.Connection 0 libapple_nghttp2.dylib 0xa6ec nghttp2_session_del + 124 1 CFNetwork 0xace4c + 428 2 CFNetwork 0xacc80 + 36 3 libdispatch.dylib 0x2370 _dispatch_call_block_and_release + 32 4 libdispatch.dylib 0x40d0 _dispatch_client_callout + 20 5 libdispatch.dylib 0xb6d8 _dispatch_lane_serial_drain + 744 6 libdispatch.dylib 0xc214 _dispatch_lane_invoke + 432 7 libdispatch.dylib 0xd670 _dispatch_workloop_invoke + 1732 8 libdispatch.dylib 0x17258 _dispatch_root_queue_drain_deferred_wlh + 288 9 libdispatch.dylib 0x16aa4 _dispatch_workloop_worker_thread + 540 10 libsystem_pthread.dylib 0x4c7c _pthread_wqthread + 288 11 libsystem_pthread.dylib 0x1488 start_wqthread + 8 ** The stack trace does not point to any code within our product codebase, hence making it difficult to pinpoint the root cause of the issue as there are multiple network calls running concurrently during the app's runtime.
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445
Jan ’25
Crash in connection loader from CFNetwork with stack traces referring to internal Apple SDKs
We found there is a significant crash reports (most of them are from iOS 17, the rest are iOS 16 and 15) comes from network loader from CFNetwork. Apparently it seems there are two types of crashes if we checked from the stack trace, the one we found from both Xcode organizer and 3rd party crash reporter is referring to URLConnectionLoader::loadWithWhatToDo and the other one from our 3rd party crash reporter (didn’t found the report from Xcode organizer) referring to _CFURLResponseCreateFromArchiveList (this one only happened on iOS 17.5 and later devices). It seems that they are both kinda similar which might point to the same root cause. From what I’ve seen, we never touch the lower level API directly, we usually use the URLSession to manage our API request. The crashed stack trace also didn’t give any indication about which of our app code that triggered the crash, it only shows calls to Apple’s internal SDKs so we are unsure how to approach this issue meanwhile the crash event already reached 800+ in the last 30 days. Unfortunately, we cannot reproduce the issue as the stack trace itself seems unclear to us. I have submitted a report through feedback assistant with number: FB14679252. Would appreciate if anyone can give any advice on what we can do to avoid this in the future and probably any hint on why it could happened. Hereby I attached the crash reports that we found each from Xcode crash report and our 3rd party crash reporter (the report said it crashed on com.apple.CFNetwork.LoaderQ) so you could get a glimpse of the similarity. Xcode crash report xcode crash report.crash 3rd party crash report 3rd party crash report.txt
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Mar ’25
Applications stuck in UDP sendto syscall
Hi, We’re seeing our build system (Gradle) get stuck in sendto system calls while trying to communicate with other processes via the local interface over UDP. To the end user it appears that the build is stuck or they will receive an error “Timeout waiting to lock XXX. It is currently in use by another Gradle instance”. But when the process is sampled/profiled, we can see one of the threads is stuck in a sendto system call. The only way to resolve the issue is to kill -s KILL <pid> the stuck Gradle process. A part of the JVM level stack trace: "jar transforms Thread 12" #90 prio=5 os_prio=31 cpu=0.85ms elapsed=1257.67s tid=0x000000012e6cd400 nid=0x10f03 runnable [0x0000000332f0d000] java.lang.Thread.State: RUNNABLE at sun.nio.ch.DatagramChannelImpl.send0(java.base@17.0.10/Native Method) at sun.nio.ch.DatagramChannelImpl.sendFromNativeBuffer(java.base@17.0.10/DatagramChannelImpl.java:901) at sun.nio.ch.DatagramChannelImpl.send(java.base@17.0.10/DatagramChannelImpl.java:863) at sun.nio.ch.DatagramChannelImpl.send(java.base@17.0.10/DatagramChannelImpl.java:821) at sun.nio.ch.DatagramChannelImpl.blockingSend(java.base@17.0.10/DatagramChannelImpl.java:853) at sun.nio.ch.DatagramSocketAdaptor.send(java.base@17.0.10/DatagramSocketAdaptor.java:218) at java.net.DatagramSocket.send(java.base@17.0.10/DatagramSocket.java:664) at org.gradle.cache.internal.locklistener.FileLockCommunicator.pingOwner(FileLockCommunicator.java:61) at org.gradle.cache.internal.locklistener.DefaultFileLockContentionHandler.maybePingOwner(DefaultFileLockContentionHandler.java:203) at org.gradle.cache.internal.DefaultFileLockManager$DefaultFileLock$1.run(DefaultFileLockManager.java:380) at org.gradle.internal.io.ExponentialBackoff.retryUntil(ExponentialBackoff.java:72) at org.gradle.cache.internal.DefaultFileLockManager$DefaultFileLock.lockStateRegion(DefaultFileLockManager.java:362) at org.gradle.cache.internal.DefaultFileLockManager$DefaultFileLock.lock(DefaultFileLockManager.java:293) at org.gradle.cache.internal.DefaultFileLockManager$DefaultFileLock.<init>(DefaultFileLockManager.java:164) at org.gradle.cache.internal.DefaultFileLockManager.lock(DefaultFileLockManager.java:110) at org.gradle.cache.internal.LockOnDemandCrossProcessCacheAccess.incrementLockCount(LockOnDemandCrossProcessCacheAccess.java:106) at org.gradle.cache.internal.LockOnDemandCrossProcessCacheAccess.acquireFileLock(LockOnDemandCrossProcessCacheAccess.java:168) at org.gradle.cache.internal.CrossProcessSynchronizingCache.put(CrossProcessSynchronizingCache.java:57) at org.gradle.api.internal.changedetection.state.DefaultFileAccessTimeJournal.setLastAccessTime(DefaultFileAccessTimeJournal.java:85) at org.gradle.internal.file.impl.SingleDepthFileAccessTracker.markAccessed(SingleDepthFileAccessTracker.java:51) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer.markAccessed(DefaultCachedClasspathTransformer.java:209) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer.transformFile(DefaultCachedClasspathTransformer.java:194) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer.lambda$cachedFile$6(DefaultCachedClasspathTransformer.java:186) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer$$Lambda$368/0x0000007001393a78.call(Unknown Source) at org.gradle.internal.UncheckedException.unchecked(UncheckedException.java:74) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer.lambda$transformAll$8(DefaultCachedClasspathTransformer.java:233) at org.gradle.internal.classpath.DefaultCachedClasspathTransformer$$Lambda$372/0x0000007001398470.call(Unknown Source) at java.util.concurrent.FutureTask.run(java.base@17.0.10/FutureTask.java:264) at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64) at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@17.0.10/ThreadPoolExecutor.java:1136) at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@17.0.10/ThreadPoolExecutor.java:635) at java.lang.Thread.run(java.base@17.0.10/Thread.java:840) A part of the process sample: 2097 Thread_3879661: Java: jar transforms Thread 12 + 2097 thread_start (in libsystem_pthread.dylib) + 8 [0x18c42eb80] ...removed for brevity... + 2097 Java_sun_nio_ch_DatagramChannelImpl_send0 (in libnio.dylib) + 84 [0x102ef371c] + 2097 __sendto (in libsystem_kernel.dylib) + 8 [0x18c3f612c] We have observed the following system logs around the time the issue manifests: 2025-08-26 22:03:23.280255+0100 0x3b2c00 Default 0x0 0 0 kernel: cfil_hash_entry_log:6088 <CFIL: Error: sosend_reinject() failed>: [4628 java] <UDP(17) in so 9e934ceda1c13379 50826943645358435 50826943645358435 ag> 2025-08-26 22:03:23.280267+0100 0x3b2c00 Default 0x0 0 0 kernel: cfil_service_inject_queue:4472 CFIL: sosend() failed 22 The issue seems to be rooted in the built-in Application Firewall, as disabling it “fixes” the issue. It doesn’t seem to matter that the process is on the “allow” list. We’re using Gradle 7.6.4, 8.0.2 and 8.14.1 in various repositories, so the version doesn’t seem to matter, neither does which repo we use. The most reliable way to reproduce is to run two Gradle builds at the same time or very quickly after each other. We would really appreciate a fix for this as it really negatively affects the developer experience. I've raised FB19916240 for this. Many thanks,
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How to reset Local Network Privacy settings?
On macOS 15, if a program installed in /Applications is allowed to connect to a PostgreSQL server on another machine on the local network, a program launched in debug mode from Xcode is not allowed to connect to the local network, and no prompt appears. Although it is possible to turn off registered programs in Local Network Privacy in Beta 2, permissions for programs launched from Xcode cannot be obtained at all. Does anyone know how to solve this problem?
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2.5k
Jan ’25
macOS Network Extension deactivation fails with authorizationRequired
Hello, I have a .app that runs as LaunchDaemon and configured to be an Agent (LSUIElement) that is stored in /Applications. Installing network extensions works, but deactivation fails with OSSystemExtensionErrorDomain error 13 (authorization required). requestNeedsUserApproval is not called for deactivation, but it's called when being activated. Any ideas? Thank you! P.S. It works on Debug, just not on Release...
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Can an e-commerce iOS app running in the Xcode Simulator disrupt NETransparentProxyProvider and NEFilterDataProvider, causing DNS failures on macOS
Description: We are investigating an issue where running a specific e-commerce iOS app inside the Xcode Simulator intermittently disrupts the Mac’s network connectivity. When the app is launched in the Simulator, our NETransparentProxyProvider and NEFilterDataProvider extensions occasionally stop receiving traffic correctly, and shortly afterward the entire macOS DNS resolution fails. Once this happens, all apps on the Mac lose internet access until mac is restarted. Disabling extensions also fixing the issue. This issue only appears when the app runs in the Xcode Simulator. I would like to confirm: Is it possible for traffic patterns or network behavior inside the Simulator to interfere with system-level Network Extension providers on macOS? Are there known limitations or conflicts between the Simulator’s virtual networking interfaces and Network Extensions? Any recommended debugging steps or best practices to isolate this behavior? Any guidance, known issues, or suggestions would be appreciated.
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