General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Network Extension (including Wi-Fi on iOS): See Network Extension Resources Wi-Fi Fundamentals TN3111 iOS Wi-Fi API overview Wi-Fi Aware framework documentation Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Wi-Fi Fundamentals Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post WirelessInsights framework documentation iOS Network Signal Strength Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

I'm seeing fully reproducible issues with URLSession on iOS 18.4 RC Simulator running from Xcode 16.3 RC. URLSession seems to get into a broken state after a second app run. The following sample succeeds in fetching the JSON on first app run but when the app is closed and ran again it fails with one of these errors: Error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." Error: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." I'm wondering if this something related to my OS setup or is this due to internal URLSession changes in iOS 18.4. Already submitted as FB17006003. Sample code attached below: import SwiftUI @main struct NetworkIssue18_4App: App { var body: some Scene { WindowGroup { ContentView() } } } struct ContentView: View { @State private var message: String = "" var body: some View { VStack { Text(message) Button("Try Again") { Task { await fetch() } } } .task { await fetch() } } private func fetch() async { message = "Loading..." let url = URL(string: "https://poetrydb.org/title/Ozymandias/lines.json")! let session = URLSession.shared do { let response = try await session.data(from: url) print("Response: \(response)") message = "Success, data length: \(response.0.count)" } catch { print("Error: \(error)") message = "Error: \(error.localizedDescription)" } } }

It's not yet fully clear why and when does this crash occur, but I'm creating this post so there's a centralized thread for this. Some hints collected so far: The crash is occurring for existing Xcode projects opened with new Xcode 26.0 beta (17A5241e); no one's been able to reproduce on a project created in Xcode 26. I even tried creating a project with Xcode 16.2 and open it in Xcode 26, but it's all working fine there (don't have older Xcode at the moment, to try with many versions) It crashes right at the line of code that initializes URLSessionConfiguration. If you call URLSession() without parameters (which is deprecated as of iOS 13), the session initializes without the crash. It's NOT occurring only for libraries installed through package manages. In a project where it crashes, one should be able to reproduce by adding URLSessionConfiguration.default as the first line in didFinishLaunchingWithOptions It crashes when running an app on an iOS 26 simulator. (I don't have a device running beta iOS 26 to test on it!) It's working fine when running the app on a simulator or a device running iOS 18 or older. Related issue on Firebase GitHub repo: https://github.com/firebase/firebase-ios-sdk/issues/14948 Sorry to not be able to provide more info at the moment. I wanted to report this so in case someone from Apple knows about it, we could at least get some feedback or workarounds, until fix is released -- and, to prevent us all from duplicating this report in repositories of each library, as this isn't related to libraries.

Aloha. Opening and closing VPN tunnels results in as many utun interfaces as the amount of times the tunnel has been opened. These interfaces stay present and seem to be removed only upon system reboot. We are using the NetworkExtension as a SystemExtension on macOS to create the virtual interfaces. Is this the normal behaviour. Has anybody else experienced this? utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1380 inet6 fe80::8038:c353:17cd:c422%utun0 prefixlen 64 scopeid 0xf nd6 options=201<PERFORMNUD,DAD> utun1: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 2000 inet6 fe80::cfb6:1324:d7e9:5d5%utun1 prefixlen 64 scopeid 0x10 nd6 options=201<PERFORMNUD,DAD> utun2: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun3: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun4: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun5: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun6: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun7: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun8: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM>

There is a problem with the Apple local network setting api, iOS18 system, you turn off the local network permissions of the APP, uninstall the APP, and then re-install, the local network permissions even if opened, there is no effect, only restart the phone is useful

Hi, Having an issue on one mac using Xcode 16.3 and simulator 18.4. macSO 15.4 We are checking for bonjour: authorizationBrowser = NWBrowser(for: .bonjour(type: "_bonjour._tcp", domain: nil), using: parameters) authorizationBrowser?.stateUpdateHandler = { [weak self] newState in switch newState { ... } } However at the command line we get the error: nw_browser_fail_on_dns_error_locked [B1] nw_browser_dns_service_browse_callback failed: PolicyDenied(-65570) Any idea why this is happening? or what this error means? Thanks Antz

Hi folks, I would like to ask for clarification regarding Local Network Policy. I found 2 cases where I think the behaviour differs from the documentation. 1. Use case In a CI environment, we have multiple services (LaunchAgents) which require Local Network Access. We are fine by manually approving the Local Network Permission once (per service), but we also require these services to be able to self-update. Self update results in downloading the a binary with an (obviously) different UUID, which seems to result in re-triggering the Local Network Consent prompt. Strange thing: If I don't click either buttons (Allow of Reject), just restart macOS, it will result in an enabled entry in Privacy &amp; Security &gt; Local Network. I read a reply somewhere on this forum by an Apple engineer that the approval process is a mix of Bundle ID + UUID + other components, so I would expect a new binary with the same properties (but different UUID) to be already whitelisted. Is this behaviour intended? 2. Use Case Given the first issue, I decided to do this in the "right way". I was happy to read this sentence in the documentation: If you ship a launchd agent that’s not installed using SMAppService, make macOS aware of the responsible code by setting the AssociatedBundleIdentifiers property in your launchd property list. I have a properly setup (and code signed) Application, for which I have enabled Local Network permission in Privacy &amp; Security. I have a standalone LaunchAgent, which runs a long running binary from a user directory. The agent is managed with launchd, and in this sense it is "independent" from the main Application Bundle. I have setup AssociatedBundleIdentifiers in the Agent plist, to associate it with the Application. The TeamIdentifier of the 2 binaries are the same. Based on the documentation, this should be enough for my agent to signal macOS that the responsible code is the Application Bundle (which is already enabled from Local Network POV). Instead, once the LaunchAgent starts, the Local Network Consent popup appears for the binary. I would expect the Application to be the responsible code, thus no more Consent popup. Is this behaviour intended? I need this service to run as user, so I cannot just circumvent the Consent popup by running as a Daemon or Root. Nor I would like to manage the Agent with ServiceManagement. What do you guys think, have I misunderstood the documentation?

On iOS 26 beta 5, it is impossible to add a VPN configuration when a passcode is set on the device. Every time, all it does is redirect to the Settings app with no prompt for passcode. The only way around this is to disable passcode on the device so adding a VPN configuration doesn’t have to open the Settings app. This issue happened intermittently in the past with previous iOS 26 betas and even on iOS 18, but the problem has worsened on iOS 26 beta 5 to the point where you have to turn off passcode to add a VPN. Feedback ID: FB17974765

After pairing and having subscribed to a service, and even after having exchanged messages, the service fails after a period of time and both devices need to pair again.

Hi, my app makes tcp connection successfully on macOS 15. But, after restarting Mac, the app fails to make tcp connection. The app is allowed in Settings > Privacy & Security > Local Network. If I deny it and then allow it again, the app can make tcp connection successfully. Is it a macOS Sequoia bug?

We have an application which is written in Swift, which activates network extension (Transparent Proxy). We want to use MDM deployment for this network system extension. Our Transparent Proxy module is a system extension, which is exposing an app proxy provider interface (We are using NETransparentProxyProvider class and in extension’s Info.plist we use com.apple.networkextension.app-proxy key.) We don’t have any remote server setup to forward the traffic, instead we open a connection with a certain localhost:port to redirect the traffic which is received in our transparent proxy. We have another module that listens to the particular localhost:port to process the traffic further. As per https://developer.apple.com/documentation/devicemanagement/vpn/transparentproxy documentation, we noticed that we can use the VPN payload with app-proxy as Provider Type for Transparent Proxy. We were able to install the profile created via Jamf Pro and also while in stalling our product the Transparent Proxy gets mapped with the one which is installed via profile. However after that the network is broken and hence unable to browse anything. We are suspecting the remote server filed is causing this. So we tried creating the custom profile without remote server address for VPN payload, but we are unable to install the profile. It throws below error: 2025-02-11 16:43:55.193348+0530 0x2f880 Error 0x0 6815 0 mdmclient: (NetworkExtension) [com.apple.networkextension:] Failed to save configuration DGWebProxy because it is invalid: Error Domain=NEConfigurationErrorDomain Code=2 "configuration is invalid: Missing server address" UserInfo={NSLocalizedDescription=configuration is invalid: Missing server address}
2025-02-11 16:43:55.193376+0530 0x2f880 Error 0x0 6815 0 mdmclient: (NetworkExtension) [com.apple.networkextension:] NEProfileIngestion Error occurred when saving configuration 'DGWebProxy': configuration is invalid: configuration is invalid: Missing server address 
2025-02-11 16:43:55.196159+0530 0x2f880 Error 0x0 6815 7 mdmclient: [com.apple.ManagedClient:CPDomainPlugIn] [ERROR] [0:MDMDaemon:CPDomainPlugIn:<0x2f880>] <<<<< PlugIn: InstallPayload [NEProfileIngestionPlugin] Error: Error Domain=ConfigProfilePluginDomain Code=-319 "The ‘VPN Service’ payload could not be installed. The VPN service could not be created." UserInfo={NSLocalizedDescription=The ‘VPN Service’ payload could not be installed. The VPN service could not be created.} <<<<<
2025-02-11 16:43:55.196826+0530 0x2f880 Error 0x0 6815 7 mdmclient: [com.apple.ManagedClient:MDMDaemon] [ERROR] [0:MDMDaemon:<0x2f880>] [CE] PlugIn_InstallPayload ==> Error Domain=ConfigProfilePluginDomain Code=-319 "The ‘VPN Service’ payload could not be installed. The VPN service could not be created." UserInfo={NSLocalizedDescription=The ‘VPN Service’ payload could not be installed. The VPN service could not be created.} Can we create MDM profile for Transparent Proxy without remote server address?

I couldn't find any mention in the Wi-Fi Aware documentation https://developer.apple.com/documentation/WiFiAware about the possibilities of the Wi-Fi Aware connection during the app working in the background execution mode (background state). Does the framework keep the connection alive when the app goes to the background state? Is there anything similar concept to CoreBluetooth state restoration available in the case of the Wi-Fi Aware framework?

In our setup, our Transparent Proxy (call it TP1) funnels traffic to a helper process running on the same machine (call it Helper), which then actually sends out the traffic to the wider Internet. Now say there's another Transparent Proxy, TP2, on the same machine. Assuming TP1 gets hold of the traffic first, the sequence would look like so: Safari --> TP1 --> Helper --> TP2 We want to make it appear to TP2 that the incoming traffic is from Safari, rather than from the Helper process. We are aware of the Network framework's setMetadata API, but this does not look appropriate for us to use here. The Helper process is pre-existing Golang code, which at best can interface with "pure" (ie BSD) sockets-based C code. In order to use the setMetadata API, looks like we will need to rewrite the entire networking logic to use nw_connection_t (or similar) API, which is too much work, so is infeasible for us to use. Is there a way to make the setMetadata API work at a socket level? e.g., associate the metadata with a socket so that whatever data is sent out on the socket by the Helper will seem to TP2 to be coming from the desired source process. Assuming there isn't such a way, please consider this an Enhancement Request to make it so! Also, this reveals another complication: If and when this Enhancement is implemented, our own TP1 (which interepted the traffic in the first place) would end up thinking that the traffic is from Safari, so ends up re-intercepting it, causing a loop. Safari --> TP1 --> Helper (invokes setMetadata) --> TP1 --> Helper ... Which leads to the next Enhancement Request: Please extend the API to allow setting of the "last-hop" source process in addition to the original source application. If the last-hop source process info is set, our TP1 can query this property, see that it's coming from our own Helper process, and skip interception. In summary, here are the Enhancement Requests: Allow setMetadata API to work at a socket level Allow setting of "last-hop" source process in the metadata, in addition to the original source application More succinctly, please allow setting of metadata to cater to cases where the actual egress happens via a (different) helper process that uses pure C sockets based API. I have also filed this as a Feedback with Apple, at FB16048393.

There is no available API that allows you to connect to Android. The current APIs that are provided are not compatible outside of the Apple Ecosystem. For example, Android requires you to set a service name and a password where iOS sets a service and a PIN authentication strategy in a specific format that’s not compatible. It looks like the implementation is not following the Wifi Aware Specifications. To enable cross platform interoperability while providing security, could you adopt the same strategy as with Bluetooth and enable iOS users to enable the sharing and subscription of services with Everyone.

Hi! I've noticed that the IP_RECVIF socket option, i.e.: int y = 1; setsockopt(fd, IPPROTO_IP, IP_RECVIF, &y, sizeof(y)); does not seem to work if the socket is proxied by a NETransparentProxyProvider type network extension: there's no ancillary data in messages received with recvmsg. As soon as I disable the network extension, recvmsg starts returning ancillary data containing the interface name. This seems to break some applications which rely on IP_RECVIF in the presence of a transparent proxy, making it, in fact, not transparent. One such example is Apple's own libresolv, which relies on IP_RECVIF and breaks if there's no ancillary data in the recvmsg result. I don't think that this is the intended behaviour, since IPV6_PKTINFO seems to work fine. I've filed a bug report (FB17586550) about this, however, I would greatly appreciate if someone could point me in the direction of a workaround.

When a VPN is active, RCS messaging does not work on iOS 18. I work on an iOS VPN app, and we were very appreciative of the excludeCellularServices network flag that was released during the iOS 16 cycle. It's a great solution to ensure the VPN doesn't interfere with cellular network features from the cellular provider. Separately - As a user, I'm excited that iOS 18 includes RCS messaging. Unfortunately, RCS messaging is not working when our VPN is active (when checking on the iOS 18 release candidate). My guess is that RCS is not excluded from the VPN tunnel, even when excludeCellularServices is true. It seems like RCS should be added in this situation, as it is a cell provider service. Can RCS be added as a service that is excluded from the VPN tunnel when excludeCellularServices is true? (I've also sent this via feedback assistant, as 15094270.)

We are developing an iOS application that is interacting with HTTP APIs that requires us to put a unique UUID (a nonce) as an header on every request (obviously there's more than that, but that's irrilevant to the question here). If the same nonce is sent on two subsequent requests the server returns a 412 error. We should avoid generating this kind of errors as, if repeated, they may be flagged as a malicious activity by the HTTP APIs. We are using URLSession.shared.dataTaskPublisher(for: request) to call the HTTP APIs with request being generated with the unique nonce as an header. On our field tests we are seeing a few cases of the same HTTP request (same nonce) being repeated a few seconds on after the other. Our code has some retry logic only on 401 errors, but that involves a token refresh, and this is not what we are seeing from logs. We were able to replicate this behaviour on our own device using Network Link Conditioner with very bad performance, with XCode's Network inspector attached we can be certain that two HTTP requests with identical headers are actually made automatically, the first request has an "End Reason" of "Retry", the second is "Success" with Status 412. Our questions are: can we disable this behaviour? can we provide a new request for the retry (so that we can update headers)? Thanks, Francesco

I was excited to find out about Wi-Fi Aware in i[Pad]OS 26 and was eager to experiment with it. But after wiping and updating two devices (an iPhone 11 Pro and a 2018 11" iPad Pro) to Beta 1 I found out that neither of them support Wi-Fi Aware 🙁. What current and past iPhone and iPad models support Wi-Fi Aware? And is there a new UIRequiredDeviceCapabilities key for it, to indicate that an app requires a Wi-Fi Aware capable device?

When setting up a packet tunnel with a profile that has includeAllNetworks set to true, we seemingly cannot send any traffic inside the tunnel using any kind of an API. We've tried using BSD sockets, as we ping a host only reachable within the tunnel to establish whether we have connectivity - this does not work. When using NWConnection from the Network framework and specifying the required interface via virtualInterface from the packet tunnel, the connection state never reaches ready. Our interim solution is to, as ridiculous as it sounds, include a whole userspace networking stack so we can produce valid TCP packets just to send into our own tunnel. We require a TCP connection within our own tunnel to do some configuration during tunnel setup. Is there no better solution?

Hi All, I am currently working on a Network Extension App for MacOS using 3 types of extensions provided by Apple's Network Extension Framework. Content Filter, App Proxy (Want to get/capture/log all HTTP/HTTPS traffic), DNS Proxy (Want to get/capture/log all DNS records). Later parse into human readable format. Is my selection of network extension types correct for the intended logs I need? I am able to run with one extension: Main App(Xcode Target1) <-> Content Filter Extension. Here there is a singleton class IPCConnection between App(ViewController.swift) which is working fine with NEMachServiceName from Info.plist of ContentFilter Extension(Xcode Target2) However, when I add an App Proxy extension as a new Xcode Target3, I think the App and extension's communication getting messed up and App not getting started/Crashing. Here, In the same Main App, I am adding new separate IPCConnection for this extension. Here is the project organization/folder structure. MyNetworkExtension ├──MyNetworkExtension(Xcode Target1) │ ├── AppDelegate.swift │ ├── Assets.xcassets │ ├── Info.plist │ ├── MyNetworkExtension.entitlement │ | ── Main │ |-----ViewController.swift │ └── Base.lproj │ └── Main.storyboard ├── ContentFilterExtension(Xcode Target2) │ ├── ContentFilterExtension.entitlement │ │ ├── FilterDataProvider.swift │ │ ├── Info.plist │ │ ├── IPCConnection.swift │ │ └── main.swift ├── AppProxyProviderExtension(Xcode Target3) │ ├── AppProxyProviderExtension.entitlement │ │ ├── AppProxyIPCConnection.swift │ │ ├── AppProxyProvider.swift │ │ ├── Info.plist │ │ └── main.swift └── Frameworks ├── libbsm.tbd └── NetworkExtension.framework Is my Approach for creating a single Network Extension App with Multiple extensions correct or is there any better approach of project organization that will make future modifications/working easier and makes the maintenance better? I want to keep the logic for each extension separate while having the same, single Main App that manages everything(installing, activating, managing identifiers, extensions, etc). What's the best approach to establish a Communication from MainApp to each extension separately, without affecting one another? Is it good idea to establish 3 separate IPC Connections(each is a singleton class) for each extension? Are there any suggestions you can provide that relates to my use case of capturing all the network traffic logs(including HTTP/HTTPS, DNS Records, etc), especially on App to Extension Communication, where my app unable to keep multiple IPC Connections and maintain them separately? I've been working on it for a while, and still unable to make the Network Extension App work with multiple extensions(each as a new Xcode target). Main App with single extension is working fine, but if I add new extension, App getting crashed. I suspect it's due to XPC/IPC connection things! I really appreciate any support on this either directly or by any suggestions/resources that will help me get better understand and make some progress. Please reach out if in case any clarifications or specific information that's needed to better understand my questions. Thank you very much

I have been battling this intermittent error for some time. It is generally random and has been difficult to reproduce until yesterday when I stumbled across a way to reproduce it each time. I can cause the code to throw this error: Task <70E3909F-8C30-4F34-A8B0-4AF3B41DD81B>.<1> finished with error [-1001] Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo={_kCFStreamErrorCodeKey=-2103, _NSURLErrorFailingURLSessionTaskErrorKey=BackgroundDownloadTask <70E3909F-8C30-4F34-A8B0-4AF3B41DD81B>.<1>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "BackgroundDownloadTask <70E3909F-8C30-4F34-A8B0-4AF3B41DD81B>.<1>", "LocalDownloadTask <70E3909F-8C30-4F34-A8B0-4AF3B41DD81B>.<1>" ), NSLocalizedDescription=The request timed out., _kCFStreamErrorDomainKey=4, NSErrorFailingURLStringKey=https://redacted*, NSErrorFailingURLKey=https://redacted*} *"redacted" is the backend URL, and it is the correct and same path for each immediately after restarting an actual device. I have been over the following threads with no results: What is kCFStreamErrorCodeKey=-4 (kCFStreamErrorDomainKey=4) Request timed out with _kCFStreamErrorCodeKey=60 How to better diagnose -1001 "The request timed out." URLSession errors Random timed out error on app start Because I was able to reproduce it, I have been able to get the following logs: Console Logs.txt Last bit of information is that I had Network Instruments running, and when this error occurred, I found that the Connection ID was "No Connection" and it appears the request was never actually sent, though it waited the full time out for a backend response. Any help would be appreciated. This data request is being used after sending a certain APNs to update necessary data in the background, and has been the source of many user complaints.