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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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adhoc ipa, installed on iOS 18 devices, udp and tcp cannot access the local network, such as 17.25.11.128
I have read all the information and forum posts about local network, such as TN3179, etc., and have added NSLocalNetworkUsageDescription, but it does not solve my problem. The problem I encountered is described as follows: Device: iOS18.1.1 Signing method: automatic Xcode debug directly runs, and the app can access 17.25.11.128 normally. However, relase run or packaged into adhoc installation, this IP cannot be accessed. There is a phenomenon that the app package of the App Store can also be used. Our test team has few iOS18+ devices, and internal testing is not possible. Please contact us as soon as possible, thank you. ======= 我已经了解了所有关于local network 相关的资料和论坛帖子,比如TN3179 等等, 已经添加了 NSLocalNetworkUsageDescription, 但是不解决我的问题。 我遇到的问题描述如下: 设备:iOS18.1.1 签名方式:自动 xcode debug 直接运行,app是可以正常访问17.25.11.128的。 但是 relase run 或者 打包成 adhoc 安装,就无法访问这个IP了。 有一个现象, App Store 的app包 也是可以的。 我们的测试团队,iOS18+的设备就没几个,还不能内部测试了。请尽快联系我们,谢谢。
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153
May ’25
Securely transmit UIImage to app running on desktop website
Hello everyone, I'm trying to figure out how to transmit a UIImage (png or tiff) securely to an application running in my desktop browser (Mac or PC). The desktop application and iOS app would potentially be running on the same local network (iOS hotspot or something) or have no internet connection at all. I'm trying to securely send over an image that the running desktop app could ingest. I was thinking something like a local server securely accepting image data from an iPhone. Any suggestions ideas or where to look for more info would be greatly appreciated! Thank you for your help.
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67
May ’25
iPhone failure to get IP from DHCP on WiFi model RN171
I have written an App which extracts data, over WiFi, from an instrument that creates its own WiFi Hotspot. The instrument provides no internet connection. The iPad version of this App is connects fine and is assigned an IP address by DHCP server running on a MicroChip RN171 wifi module. iOS assigns an obscure IP address on a completely different subnet. I understand this is iOS' way of "Complaining" that is wasn't assigned an IP address. Consequently in the case of the iPhone I am forced to manually assign an IP address for the iPhone, the mask and the gateway. Only then is the connection successful. Anyone know why the iPhone won't talk DHCP to a WiFi module not connected to the internet? Are there perhaps some parameters that I need to adjust on either the iPhone or WiFi module?
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113
May ’25
Replacing Packet Filter (pf) with Content Filter for VPN Firewall Use Case
Hi, We're in the process of following Apple’s guidance on transitioning away from Packet Filter (pf) and migrating to a Network Extension-based solution that functions as a firewall. During this transition, we've encountered several limitations with the current Content Filter API and wanted to share our findings. Our VPN client relies on firewall functionality to enforce strict adherence to split tunneling rules defined via the routing table. This ensures that no traffic leaks outside the VPN tunnel, which is critical for our users for a variety of reasons. To enforce this, our product currently uses interface-scoped rules to block all non-VPN traffic outside the tunnel. Replicating this behavior with the Content Filter API (NEFilterDataProvider) appears to be infeasible today. The key limitation we've encountered is that the current Content Filter API does not expose information about the network interface associated with a flow. As a workaround, we considered using the flow’s local endpoint IP to infer the interface, but this data is not available until after returning a verdict to peek into the flow’s data—at which point the connection has already been established. This can result in connection metadata leaking outside the tunnel, which may contain sensitive information depending on the connection. What is the recommended approach for this use case? NEFilterPacketProvider? This may work, but it has a negative impact on network performance. Using a Packet Tunnel Provider and purely relying on enforceRoutes? Would this indeed ensure that no traffic can leak by targeting a specific interface or by using a second VPN extension? And more broadly—especially if no such approach is currently feasible with the existing APIs—we're interpreting TN3165 as a signal that pf should be considered deprecated and may not be available in the next major macOS release. Is that a reasonable interpretation?
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136
May ’25
Network Framework peer to peer limitations
Hi all, We've been exploring the capabilities of the Network.framework for peer-to-peer communication and have run into some behavior that we haven't been able to fully explain with the existing documentation. In our tests, we’re working with 12 iOS devices, all disconnected from Wi-Fi to force communication over Apple Wireless Direct Link (AWDL). While using the Network.framework to create peer-to-peer connections, we observed that the number of connected peers never exceeded 8, despite all 12 devices being active and configured identically. Some questions we’re hoping to get clarification or discussion on: Is there a known upper limit to the number of peer-to-peer connections supported via AWDL? Are there conditions under which the framework or system limits or throttles visible peers? Does AWDL behavior vary by hardware model, iOS version, or backgrounding state of the app? Is there any official documentation or guidance around peer discovery or connection limits when using NWBrowser and NWConnection in a peer-to-peer context? We’d appreciate any insights from the Apple engineering team or other developers who have worked with larger peer groups using Network.framework in peer-to-peer mode.
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173
May ’25
NWConnections in Network Extension Redirected to Proxy
We have a setup where the system uses proxy settings configured via a PAC file. We are investigating how NWConnection behaves inside a Network Extension (NETransparentProxyProvider) with a transparent proxy configuration based on this PAC file. Scenario: The browser makes a connection which the PAC file resolves as "DIRECT" (bypassing the proxy) Our Network Extension intercepts this traffic for analysis The extension creates a new connection using NWConnection to the original remote address. The issue: despite the PAC file’s "DIRECT" decision, NWConnection still respects the system proxy settings and routes the connection through the proxy. Our questions: Is it correct that NWConnection always uses the system proxy if configured ? Does setting preferNoProxies = true guarantee bypassing the system proxy? Additionally: Whitelisting IPs in the Network Extension to avoid interception is not a viable solution because IPs may correspond to multiple services, and the extension only sees IP addresses, not domains (e.g., we want to skip scanning meet.google.com traffic but still scan other Google services on the same IP range). Are there any recommended approaches or best practices to ensure that connections initiated from a Network Extension can truly bypass the proxy (for example, for specific IP ranges or domains)?
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87
May ’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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92
May ’25
DNS Proxy Provider remains active after app uninstall | iOS
Hi, I've encountered a strange behavior in the DNS Proxy Provider extension. Our app implements both DNS Proxy Provider and Content Filter Providers extensions, configured via MDM. When the app is uninstalled, the behavior of the providers differs: For Content Filter Providers (both Filter Control and Filter Data Providers), the providers stop as expected with the stop reason: /** @const NEProviderStopReasonProviderDisabled The provider was disabled. */ case providerDisabled = 5 However, for the DNS Proxy Provider, the provider remains in the "Running" state, even though there is no app available to match the provider's bundle ID in the uploaded configuration profile. When the app is reinstalled: The Content Filter Providers start as expected. The DNS Proxy Provider stops with the stop reason: /** @const NEProviderStopReasonAppUpdate The NEProvider is being updated */ @available(iOS 13.0, *) case appUpdate = 16 At this point, the DNS Proxy Provider remains in an 'Invalid' state. Reinstalling the app a second time seems to resolve the issue, with both the DNS Proxy Provider and Content Filter Providers starting as expected. This issue seems to occur only if some time has passed after the DNS Proxy Provider entered the 'Running' state. It appears as though the system retains a stale configuration for the DNS Proxy Provider, even after the app has been removed. Steps to reproduce: Install the app and configure both DNS Proxy Provider and Content Filter Providers using MDM. Uninstall the app. Content Filter Providers are stopped as expected (NEProviderStopReason.providerDisabled = 5). DNS Proxy Provider remains in the 'Running' state. Reinstall the app. Content Filter Providers start as expected. DNS Proxy Provider stops with NEProviderStopReason.appUpdate (16) and remains 'Invalid'. Reinstall the app again. DNS Proxy Provider now starts as expected. This behavior raises concerns about how the system manages the lifecycle of DNS Proxy Provider, because DNS Proxy Provider is matched with provider bundle id in .mobileconfig file. Has anyone else experienced this issue? Any suggestions on how to address or debug this behavior would be highly appreciated. Thank you!
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401
May ’25
Getting WIFI SSID
Greetings I'm trying to get on iPad the SSID from the wifi I'm connected to. For that, I added the wifi entitlement and I'm requesting permission to the user for Location. Once I have it, I'm using the function CNCopySupportedInterfaces to get the interfaces, but I can only receive the en0, which using the method CNCopyCurrentNetworkInfo returns nil. I also tried using the NEHotspotNetwork.fetchCurrent and the SSID keeps being nil. So right now I'm drawing a blank. Is there any way to make it work? Thanks.
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91
May ’25
Mac can't find or register NE App Extension without App Sandbox entitlement
Recently, while developing a network extension on macOS, I encountered a very interesting issue. When the App Sandbox entitlement is included, the NE (Network Extension) can be called and run normally. However, when the App Sandbox is removed, with everything else remaining unchanged, an error occurs. The logs are as follows: Failed to find an app extension with identifier app.acmeVpnM.extension and extension point com.apple.networkextension.packet-tunnel: (null) Found 0 registrations for app.acmeVpnM.extension (com.apple.networkextension.packet-tunnel) If you add app sandbox, it will run normally. this is my container app entitlement this is my NE extension (without App SandBox) I want to know the reason for this. App sandbox shouldn't be mandatory. How can I make my NE run in an environment without app sandbox?
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64
May ’25
Unable to Find Local Network Devices in Simulator – Permission Issue on M4 Mac, macOS 15.5, Xcode 16.1
Hello, I'm running into an issue while developing an iOS app that requires local network access. I’m using the latest MacBook Air M4 with macOS sequoia 15.5 and Xcode 16.1. In the iOS Simulator, my app fails to discover devices connected to the same local network. I’ve already added the necessary key to the Info.plist: NSLocalNetworkUsageDescription This app needs access to local network devices. When I run the app on a real device and M2 Chip Macbook's simulators, it works fine for local network permission as expected. However, in the M4 Chip Macbook's Simulator: The app can’t find any devices on the local network Bonjour/mDNS seems not to be working as well I’ve tried the following without success: Restarting Simulator and Mac Resetting network settings in Simulator Confirming app permissions under System Settings > Privacy & Security Has anyone else encountered this issue with the new Xcode/macOS combo? Is local network access just broken in the Simulator for now, or is there a workaround? Thanks in advance!
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104
May ’25
URLSession download looping indefinitely until it times out
Hi, I’m trying to download a remote file in the background, but I keep getting a strange behaviour where URLSession download my file indefinitely during a few minutes, without calling urlSession(_:downloadTask:didFinishDownloadingTo:) until the download eventually times out. To find out that it’s looping, I’ve observed the total bytes written on disk by implementing urlSession(_:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:). Note that I can't know the size of the file. The server is not able to calculate the size. Below is my implementation. I create an instance of URLSession like this: private lazy var session: URLSession = { let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier) configuration.isDiscretionary = false configuration.sessionSendsLaunchEvents = true return URLSession(configuration: configuration, delegate: self, delegateQueue: nil) }() My service is using async/await so I have implemented an AsyncThrowingStream : private var downloadTask: URLSessionDownloadTask? private var continuation: AsyncThrowingStream<(URL, URLResponse), Error>.Continuation? private var stream: AsyncThrowingStream<(URL, URLResponse), Error> { AsyncThrowingStream<(URL, URLResponse), Error> { continuation in self.continuation = continuation self.continuation?.onTermination = { @Sendable [weak self] data in self?.downloadTask?.cancel() } downloadTask?.resume() } } Then to start the download, I do : private func download(with request: URLRequest) async throws -> (URL, URLResponse) { do { downloadTask = session.downloadTask(with: request) for try await (url, response) in stream { return (url, response) } throw NetworkingError.couldNotBuildRequest } catch { throw error } } Then in the delegate : public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) { guard let response = downloadTask.response, downloadTask.error == nil, (response as? HTTPURLResponse)?.statusCode == 200 else { continuation?.finish(throwing: downloadTask.error) return } do { let documentsURL = try FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false) let savedURL = documentsURL.appendingPathComponent(location.lastPathComponent) try FileManager.default.moveItem(at: location, to: savedURL) continuation?.yield((savedURL, response)) continuation?.finish() } catch { continuation?.finish(throwing: error) } } I also tried to replace let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier) by let configuration = URLSessionConfiguration.default and this time I get a different error at the end of the download: Task <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1> failed strict content length check - expected: 0, received: 530692, received (uncompressed): 0 Task <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1> finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https:/<host>:8190/proxy?Func=downloadVideoByUrl&SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, NSErrorFailingURLKey=https://<host>:8190/proxy?Func=downloadVideoByUrl&SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDownloadTask <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1>" ), _NSURLErrorFailingURLSessionTaskErrorKey=LocalDownloadTask <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1>, NSUnderlyingError=0x300d9a7c0 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x302139db0 [0x1fcb1f598]>{length = 16, capacity = 16, bytes = 0x10021ffe91e227500000000000000000}}}} The log "failed strict content length check” made me look into the response header, which has the following: content-length: 0 Content-Type: application/force-download Transfer-encoding: chunked Connection: KEEP-ALIVE Content-Transfer-Encoding: binary So it should be fine the way I setup my URLSession. The download works fine in Chrome/Safari/Chrome or Postman. My code used to work a couple of weeks before, so I expect something has changed on the server side, but I can’t find what, and I don’t get much help from the guys on the server side. Has anyone an idea of what’s going on?
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85
May ’25
TCP/IP Connection Reset --- request Timeout
send a request and it returns with timeout Integration Team are Using Fortigate as a firewall and NGINX for some reasons so we use VPN TO Access , requests always succeed but at once it failed with timeout in randomize request not specific one we are using URLSession as a network layer when I retry the same failed request again, it success the request cannot connect apigee Sec Team concern { app session hits the security gateway with lots of SYN step to try to initiate a new session and doesn’t wait for (SYN-ACK / ACK) steps to happen to make sure the connection initiated correctly and gateway consider it flooding attack }
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May ’25
Memory release problem of VPN connection object
Hello, I encountered a memory management issue while developing VPN functionality and would like to seek your advice. The specific phenomenon is as follows: Problem description: After multiple calls to the 'createTCPConnectToEndpoint' and 'create UDPSessionToEndpoint' interfaces to create connection objects, the application memory continues to grow. Even if the cancel interface is immediately called to actively release the object, the memory does not fall back. 3. Confirm that there is no other code referencing these objects, but the system does not seem to automatically reclaim memory. Attempted measures: Immediately call the cancel method after creating the object, and the memory is not reduced Use tools such as Profiler to monitor memory and confirm that objects have not been released. doubt: Is this phenomenon normal? Is there a known memory management mechanism (such as cache pooling) that causes delayed release? 2. Are there any other interfaces or methods (such as release, dispose) that need to be explicitly called? Supplementary Information: Development environment: [iOS 16, 14pm] Reproduction steps: After continuously creating connection objects, the memory grows without falling back. Could you please help confirm if there are any abnormalities and the correct memory release posture. Thank you for your support!
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56
May ’25
CarPlay vs. AccessoryKit & NEHotspotHelper
CarPlay woes. I think it's unacceptable that it silently kills an ongoing WiFi connection that has been established using ASAccessoryKit and NEHotspotHelper which is in active use. This is responsible for angry clients because their processes break a lot when they are in reach of the connected car. (And yes, they have to be in the reach of the car, because it is a diagnostic/maintenance app for cars…) Do I really need to ask my clients to unpair from CarPlay before using our app or is there another way?
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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.
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119
May ’25
App occassionally crashing while connecting to public wifi
We are using the [NEHotspotHelper supportedNetworkInterfaces] to get the Wi-Fi interface in our app, but it occasionally crashes on some devices with the following stack trace: 0 CaptiveNetwork 0x0000000221d87a4c ServerConnectionGetHandlerQueue + 0 (ServerConnection.c:509) 1 CaptiveNetwork 0x0000000221d8577c CNPluginCopySupportedInterfaces + 180 (CNPlugin.c:457) 2 NetworkExtension 0x00000001b0446618 +[NEHotspotHelper supportedNetworkInterfaces] + 32 (NEHotspotHelper.m:563) It seems like the crash is happening on apple's api of supportedNetworkInterfaces. We would like to understand the cause of the crash.
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53
May ’25
iOS 18; Can no longer connect app to camera over Ad Hoc insecure network
We have an old iOS app and an old camera that connects using Wi-Fi either using an access point or Ad Hoc network, e.g., iPhone/iPad connects to the camera's Wi-Fi directly... How it works (old legacy app/system, which cannot be redesigned): Camera is configured to Ad Hoc Wi-Fi network (insecure TCP). iPhone connects to this insecure Wi-Fi. Camera uses Bonjour service to broadcast its IP address. App reads in IP address and begin to send messages to the camera using NSMutableURLRequest, etc. All this works fine for iOS 17. But in iOS 18 step 4 stopped working. App simply doesn't get any responses! We believe we have configured ATS properly (App Store version): In panic we have also tried this in Test Flight version: The latter actually seemed to make a difference when running the app on macOS Apple Silicon. But on iOS it didn't seem to make any difference. Occasionally, I was lucky to get connection on on iPhone 16 Pro with iOS 18. But for the 'many' iPads I have tried I couldn't. I also tried to install CFNetwork profile and look at the logs but I believe I just got timeout on the requests. Questions: Why it iOS 18 different? Bonjour works fine, but NSSURLRequests doesn't Do we configure ATS correctly for this scenario? What should I look for in the Console log when CFNetwork profile is installed? Should I file a TSI? Thanks! :)
7
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134
May ’25