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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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My app suddenly getting "A server with the specified hostname could not be found"
I've had no problem running my app in a simulator or on a device, but today my app is failing on a URLRequest to my local machine (in a sim). From the same simulator I can go to Safari and manually enter the URL that the app is using (and that appears in the error message), and it works fine. I think there was a recent Xcode update; did something change in this regard?
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244
Apr ’25
Determine outgoing flow source IPs without allowing data leakage using NEFilterDataProvider
I'm looking for help with a network extension filtering issue. Specifically, we have a subclass of NEFilterDataProvider that is used to filter flows based upon a set of rules, including source IP and destination IP. We've run into an issue where the source IP is frequently 0.0.0.0 (or the IPv6 equivalent) on outgoing flows. This has made it so rules based upon source IP don't work. This is also an issue as we report these connections, but we're lacking critical data. We were able to work around the issue somewhat by keeping a list of flows that we allow that we periodically check to see if the source IP is available, and then report after it becomes available. We also considered doing a "peekBytes" to allow a bit of data to flow and then recheck the flow, but we don't want to allow data leakage on connections that should be blocked because of the source IP. Is there a way to force the operating system or network extension frameworks to determine the source IP for an outbound flow without allowing any bytes to flow to the network? STEPS TO REPRODUCE Create a network filtering extension for filtering flows using NEFilterDataProvider See that when handleNewFlow: is called, the outgoing flow lacks the source IP (is 0.0.0.0) in most cases There is this post that is discussing a similar question, though for a slightly different reason. I imagine the answer to this and the other post will be related, at least as far as NEFilterDataProvider:handleNewFlow not having source IP is considered. Thanks!
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179
Apr ’25
Flow Divert behavior
Hello, Our app uses Network Extension / Packet Tunnel Provider to establish VPN connections on macOS and iOS. We have observed that after creating a utun device and adding any IPv4 routes (NEPacketTunnelNetworkSettings.IPv4Settings), the OS automatically adds several host routes via utun to services such as Akamai, Apple Push, etc. These routes appear to correspond to TCP flows that were active at the moment the VPN connection was established. When a particular TCP flow ends, the corresponding host route is deleted. We understand this is likely intended to avoid breaking existing TCP connections. However, we find the behavior of migrating existing TCP flows to the new utun interface simply because any IPv4 route is added somewhat questionable. This approach would make sense in a "full-tunnel" scenario — for example, when all IPv4 traffic (e.g., 0.0.0.0/0) is routed through the tunnel — but not necessarily in a "split-tunnel" configuration where only specific IPv4 routes are added. Is there any way to control or influence this behavior? Would it be possible for FlowDivert to differentiate between full-tunnel and split-tunnel cases, and only preserve existing TCP flows via utun in the full-tunnel scenario? Thank you.
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112
Apr ’25
intermittent multicast socket failures, new to Sequoia, still not fixed
multicast sockets fail to send/receive on macosx, errno 65 "no route to host". Wireshark and Terminal.app (which have root privileges) both show incoming multicast traffic just fine. Normal UDP broadcast sockets have no problems. Toggling the Security&Privacy -> Local Network setting may fix the problem for some Users. There is no pattern for when multicast socket fails. Sometimes, recreating the sockets fix the problem. Restart the app, sometimes multicast fails, sometimes success (intermittent, no pattern). Reboot machine (intermittent fail) Create a fresh new user on machine, install single version of app, give app permission. (intermittent fail, same as above). We have all the normal entitlements / notarized app. Similar posts here see FB16923535, Related to FB16512666 https://forum.xojo.com/t/udp-multicast-receive-on-mac-failing-intermittant/83221 see my post from 2012 "distinguishing between SENDING sockets and RECEIVING sockets" for source code example of how we bind multicast sockets. Our other socket code is standard "Stevens, et al." code. The bind() is the call that fails in this case. https://stackoverflow.com/questions/10692956/what-does-it-mean-to-bind-a-multicast-udp-socket . Note that this post from 2012 is still relevant, and that it is a workaround to a longstanding Apple bug that was never fixed. Namely, "Without this fix, multicast sending will intermittently get sendto() errno 'No route to host'. If anyone can shed light on why unplugging a DHCP gateway causes Mac OS X multicast SENDING sockets to get confused, I would love to hear it." This may be a hint as to the underlying bug that Apple really needs to fix, but if it's not, then please Apple, fix the Sequoia bug first. These are probably different bugs because in one case, sendto() fails when a socket becomes "unbound" after you unplug an unrelated network cable. In this case, bind() fails, so sendto() is never even called. Note, that we have also tried to use other implementations for network discovery, including Bonjour, CFNetwork, etc. Bonjour fails intermittently, and also suffers from both bugs mentioned above, amongst others.
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112
Apr ’25
No route to host
I upgraded my Mac to Sequoia 15.4.1 an i hat to upgrade XCode to Version 16.3. I access a MQTT Broker by an sending an mosquitto_sub request to the Broker. Now its no longer possible the request fails i granted Network permission to my App
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178
Apr ’25
Network connectivity issue observed on OS 15.4.1
Recently, we have observed that after upgrading to OS 15.4.1, some devices are experiencing network issues. We are using a Network Extension with a transparent app proxy in our product. The user encounters this issue while using our client, but the issue persists even after stopping the client app. This appears to be an OS issue. Below is the sytem logs. In the system logs, it says [C669.1 Hostname#546597df:443 failed transform (unsatisfied (No network route), flow divert agg: 2)] event: transform:children_failed @0.001s In scutil --dns, it says not reachble. DNS configuration resolver #1 flags : reach : 0x00000000 (Not Reachable) resolver #2 domain : local options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 300000 resolver #3 domain : 254.169.in-addr.arpa options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 300200 resolver #4 domain : 8.e.f.ip6.arpa options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 300400 resolver #5 domain : 9.e.f.ip6.arpa options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 300600 resolver #6 domain : a.e.f.ip6.arpa options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 300800 resolver #7 domain : b.e.f.ip6.arpa options : mdns timeout : 5 flags : reach : 0x00000000 (Not Reachable) order : 301000 We need to restart the system to recover from the issue.
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333
May ’25
Background Download Support for Large Video Files in visionOS App
Hi everyone, I'm developing a visionOS app that allows users to download large video files (similar to a movie download experience, with each file being around 10 GB). I've successfully implemented the core video download functionality using URLSession, and everything works as expected while the app is active. Now, I’m looking to support background downloading. Specifically, I want users to be able to start a download and then leave the app (e.g., switch apps or return to the home screen) while the download continues in the background. Additionally, I’d like to confirm a specific scenario: If the user starts a download, then removes the headset (keeping the device turned on and connected to power), will the download continue in the background? Or does visionOS suspend the app or downloads in this case? I’m considering using a background URLSessionConfiguration (as done in iOS/macOS) to enable this behavior, but I’m not sure if it behaves the same way on visionOS or if there are special limitations or best practices when handling large downloads on this platform. Any insights or official guidance would be greatly appreciated! Thanks!
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107
May ’25
NE System Extension stuck on Validation By Category
Hello, I'm having some problems when install my Packet Tunnel network extension as system extension on my mac(macos 15.0). It stuck on Validation By Category. (it works well as NE app extension on ios) systemextensionsctl list --- com.apple.system_extension.network_extension enabled active teamID bundleID (version) name [state] <...> com.myteam.balabalabla.ne (1.0/1) - [validating by category] This is my install System Extension Code sample public class SystemExtension: NSObject, OSSystemExtensionRequestDelegate { private let forceUpdate: Bool private let inBackground: Bool private let semaphore = DispatchSemaphore(value: 0) private var result: OSSystemExtensionRequest.Result? private var properties: [OSSystemExtensionProperties]? private var error: Error? private init(_ forceUpdate: Bool = false, _ inBackground: Bool = false) { } // some request function i overwrite public func activation() throws -> OSSystemExtensionRequest.Result? { let request = OSSystemExtensionRequest.activationRequest(forExtensionWithIdentifier: FilePath.packageName + ".myNeName", queue: .main) request.delegate = self OSSystemExtensionManager.shared.submitRequest(request) semaphore.wait() if let error { throw error } return result } public func getProperties() throws -> [OSSystemExtensionProperties] { let request = OSSystemExtensionRequest.propertiesRequest(forExtensionWithIdentifier: FilePath.packageName + ".myNeName", queue: .main) request.delegate = self OSSystemExtensionManager.shared.submitRequest(request) semaphore.wait() if let error { throw error } return properties! } public nonisolated static func install(forceUpdate: Bool = false, inBackground: Bool = false) async throws -> OSSystemExtensionRequest.Result? { try await Task.detached { try SystemExtension(forceUpdate, inBackground).activation() }.result.get() } public nonisolated static func uninstall() async throws -> OSSystemExtensionRequest.Result? { try await Task.detached { try SystemExtension().deactivation() }.result.get() } } // And other methods I follow this post Your Friend the System Log and use this command line to collect log. After I initiated the system extension request sudo log collect --last 5m Here is my log (),I only pasted some code snippets that caught me, full version see attachments.(only include com.apple.sysextd), if need more, plz ask me. 1. Some policy missing ```log 22:00:13.818257 `sysextd` extension mockTeamID app.balabala.com.mockbalabala (1.0/1) advancing state from staging to validating 22:00:13.818263 sysextd returning cdhash for local arch arm64 of extension app.balabala.com.mockbalabala info 2025-05-01 22:00:13.818336 sysextd Extension with identifier <private> reached state <private> 22:00:13.819185 sysextd [0x9a2034b00] activating connection: mach=false listener=false peer=false name=com.apple.CodeSigningHelper 22:00:13.819911 sysextd [0x9a2034b00] invalidated after the last release of the connection object 22:00:13.821024 sysextd making activation decision for extension with teamID teamID("mockTeamID ), identifier app.balabala.com.mockbalabala 22:00:13.821026 sysextd no related kext found for sysex `app.balabala.com.mockbalabala` 22:00:13.821027 sysextd no extension policy -- activation decision is UserOption nesessionmanager.system-extensions interrupted 22:00:14.313576 sysextd [0x9a2178280] invalidated because the client process (pid 1886) either cancelled the connection or exited 22:00:14.542154 sysextd connection to com.apple.nesessionmanager.system-extensions interrupted 22:00:14.542319 sysextd [0x9a2178000] Re-initialization successful; calling out to event handler with XPC_ERROR_CONNECTION_INTERRUPTED 22:00:14.542351 sysextd connection to com.apple.nesessionmanager.system-extensions interrupted 22:00:14.589375 nesessionmanager [0x6c80e4500] activating connection: mach=true listener=false peer=false name=com.apple.sysextd And when i debug the System Extension code i notice the request Error catch by didFailWithError public func request(_: OSSystemExtensionRequest, didFailWithError error: Error) { self.error = error semaphore.signal() } error is OSSystemExtensionErrorDomain code 1 This problem has been bothering me for a long time, I would appreciate any help, if need more info, comment, thank you.
3
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278
May ’25
URLSession.dataTask(with: URL) error: Type of expression is ambiguous without a type annotation
I'm a long-time developer, but pretty new to Swift. I'm trying to get information from a web service (and found code online that I adjusted to build the function below). (Note: AAA_Result -- referenced towards the end -- is another class in my project) Trouble is, I'm getting the subject error on the call to session.dataTask. Any help/suggestions/doc pointers will be greatly appreciated!!! var result: Bool = false var cancellable: AnyCancellable? self.name = name let params = "json={\"\"}}" // removed json details let base_url = URL(string: "https://aaa.yyy.com?params=\(params)&format=json")! // removed URL specifics do { let task = URLSession.shared.dataTask(with: base_url) { data, response, error in if let error = error { print("Error: \(error)") } guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else { print("Error \(String(describing: response))") } do { let decoder = JSONDecoder() let ar = try decoder.decode(AAA_Result.self, from: response.value) // removed specific details... result = true } catch { print(error) } } task.resume() } catch { print(error) } return result }
4
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116
May ’25
Matter Generic Switch not resuming subscription on reboot
I'm developing a Matter-over-thread generic switch with 2 generic switch endpoints. This is configured as an Intermittently Connected Device with Long Idle Time. I have an Apple TV serving as the thread border router. I'm able to commission the device successfully in the Home app and assign actions to each of the buttons however when the device is rebooted the subscription doesn't appear to resume successfully and the buttons no longer work. I've tested this on various SOC's with their respective SDKs including ESP32-C6, nrf52840 and EFR32MG24 and the behaviour was consistent across all of them. It was working originally when I first started out on the ESP32-C6, then the issue popped up first when I was testing the nrf52840. In that SDK I set persistent subscriptions explicitly and it seemed to resolve the issue until it popped up again when I found that unplugging and restarting the Apple TV completely which appeared to fix the issue with subscriptions not resuming. Recently I've added a Home Pod Mini Gen 2 to the matter fabric so there are now two TBR on the network and restarting both the Apple TV and the HomePod doesn't appear to resolve the issue anymore and the subscriptions are not resuming across all three SOC's on device reboot I'm wondering if there might be something preventing the subscriptions from resuming?
2
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194
May ’25
Packet Tunnel Provider with Per App VPN debugging
We have a vpn app which uses PacketTunnelProvider. We also support per-app vpn for iOS, I need help with debugging steps for an issue I am facing recently. In the per app vpn, we have split tunneling: some urls should be tunneled while others should be direct, for tunneled urls/ips everything is working as expected. But for "direct" resources, I am facing an issue where sometimes I don't get an ACK back from the browser. Leading to a series of retransmissions and eventually the direct website not loading. Some more points of data: we do get true for the writePackets call, which seems to mean that the vpn app did write the packets to the TUN interface, but we don't get an ACK from the browser. I want some way of debugging this further so I can check if the browser actually got the packets. I also suspect that there might be a loop with packets (we are reading the packets we just wrote onto TUN), but can't say for sure since the issue is intermittent, in case of a loop, I would expect it to always help. Any help would be greatly appreciated.
3
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182
May ’25
NEHotspotHelper API
For our outdoor power supply company that builds public WiFi networks at camping sites, we want to implement the following features in our app: Scan surrounding WiFi networks When detecting specific public WiFi SSIDs, provide users with corresponding passwords Automatically connect to those WiFi networks Regarding the NEHotspotHelper API permission application, when I clicked on https://developer.apple.com/contact/request/network-extension, it redirected me to https://developer.apple.com/unauthorized/. I'm not sure where to properly apply for this permission now.
1
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43
May ’25
NEHotspotHelper API
For our outdoor power supply company that builds public WiFi networks at camping sites, we want to implement the following features in our app: Scan surrounding WiFi networks When detecting specific public WiFi SSIDs, provide users with corresponding passwords Automatically connect to those WiFi networks Regarding the NEHotspotHelper API permission application, when I clicked on https://developer.apple.com/contact/request/network-extension, it redirected me to https://developer.apple.com/unauthorized/. I'm not sure where to properly apply for this permission now.
1
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35
May ’25
When adding a VPN configuration, the Settings app doesn't continue with the configuration process
Sometimes when adding a VPN configuration, it just redirects to the Settings app and doesn’t continue with the rest of the configuration process like prompting for passcode. But it proceeds as normal after the 2nd or 3rd try. This issue is occurring on iOS 18.5 build 22F5068a but it has been a problem over several versions now. Feedback ID: FB17458055
1
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151
May ’25
split Tunnel + exclude APNs
Hello, im currently developing proxy app with XrayCore trying to bypass APNs when tunnel us up and i found .excludeAPNs property in NETunnelProviderProtocol that works only when includeAllNetworks property is also TRUE. I wonder if there is a possible way to make APNs bypass tunnel in split tunnelling mode? because we use excludedRoutes and full tunnel is not an option
1
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108
May ’25
socket connect error 65
Dear apple: Our app uses the BSD socket interface for socket communication over the local area network. However, when using the socket's connect interface, some iPhone devices fail, and the socket has also bound the local Wi-Fi card's IP using the bind interface. The errno is 65, indicating "no route." We have checked that the app has already requested local network permissions and permissions to use the local area network. The TCP server on the other end is also listening normally. Please help us see if any additional permissions need to be requested. Thank you
2
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167
May ’25
When using WKWebView in iOS 18.0 (Xcode 16.2) to open a local H5 page, the request for server resources cannot carry cookies.
In our project, we download H5 resources to the local device and then open the H5 pages through WKWebView(-loadFileURL:allowingReadAccessToURL:). When the H5 pages request server resources, cookies are required. Before opening the H5 page, we set the required cookies in the WKHTTPCookieStore using the setCookie method. Additionally, we set the allowFileAccessFromFileURLs and allowUniversalAccessFromFileURLs properties for the WebView. On other mobile phones, the cookies can be carried normally. However, on mobile phones running the iOS 18.0 system, the cookies cannot be carried. Moreover, this problem only emerged after we upgraded Xcode to version 16.2. We've also tried injecting cookies via JavaScript, but it didn't work(document.cookie = xx=${xx}; path=/; expires=weekday, xx jan xxxx xx:xx:xx GMT; Domain=example.com; Secure; SameSite=None ;). Can anyone help me on this? Thanks in advance.
2
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269
May ’25
Packet Tunnel Provider with Per App VPN debugging
We have a VPN app built using PacketTunnelProvider and support per-app VPN on iOS. We're currently investigating an issue specific to per-app VPN configurations that use split tunneling, where some URLs are routed through the VPN tunnel while others are intended to go directly. Tunneled traffic works as expected. However, for direct traffic, we observe intermittent failures where the browser does not receive an ACK, leading to repeated retransmissions and eventual page load failures. This issue appears only in per-app VPN scenarios, and we've reproduced it across multiple MDM solutions (Intune, CEM) and multiple managed browsers. It's intermittent but frequently reproducible with common public URLs routed directly. Key observations: writePackets returns true, confirming the VPN app writes packets to the TUN interface. Despite that, the browser often fails to acknowledge receipt (no ACK), suggesting it may not receive the packet at all. We suspect a possible packet loop, where packets written to TUN are immediately read back by the app. However, due to the intermittent nature of the issue, this is hard to confirm. A consistent loop would likely result in persistent failures, not sporadic ones. We are attaching: A Wireshark summary - highlighting the missing ACK and retransmission pattern. As we cannot attach the xlsx file or a zip file, we have took the screenshots of the files names as image1, image2, image3, image4 and image5 in sequence. Dails on the iOS device and MDM environment. NETunnelProviderProtocol configuration that reproduces the issue Any guidance on how to further debug this, particularly on confirming packet delivery to the browser and identifying potential loops would be greatly appreciated. Thank you. e t
3
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117
May ’25
When restarting a PC with macOS15, communication on the local network is denied for the target app even though "Local Network" in "Privacy and Security" is allowed.
We are developing a desktop app for macOS, built with Electron + Angular + Node.js. The app has the ability to access devices on the local network. We are having some trouble with the behavior of the "Local Network" feature added in macOS 15. Procedure: MacBook Pro 14inch (M1Pro) 2021, 16GB memory - macOS Sequoia15.4.1 Network Environment: The PC and the access point are connected by wire, and the target device and the access point are also connected by wire. Not connected to an external network Install the target app Start the application and allow the "Local Network" dialog that appears Open the "Local Network" item in "Privacy and Security" and make sure the target app is allowed. Confirm that you can access the target device on the local network Restart the PC Open the "Local Network" item in "Privacy and Security" and make sure the target app is allowed. Start the app and access the target device on the local network Result: Access to the target device may fail (this does not occur 100% of the time) If you turn the target app in the "Local Network" section of "Privacy and Security" OFF and then ON, you will be able to connect However, it seems that the problem may occur again if you restart your PC. According to our research, the probability of this happening increases if the target app is the only app allowed on the "local network". This happens not only with our app, but also when you follow the above steps in "Google Chrome". Based on the above investigation results, I suspect that this is a problem with the OS. What do you think?
2
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147
May ’25