Is it possible to capture or inspect UDP traffic using iOS content filter APIs (e.g., NEFilterDataProvider)? If not, what are the current technical or policy limitations that prevent UDP inspection via these frameworks?
Any insights or suggestions on these topics would be highly appreciated.
Networking
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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?
Topic:
App & System Services
SubTopic:
Networking
Tags:
Network
Background Tasks
CFNetwork
Foundation
Hello all,
Does anyone know how long it will take Apple to approve multicast entitlement approval after the Apple form is submitted?
Any input would be appreciated.
Thank you
Allyson
I am writing to seek clarification on two technical issues related to iOS frameworks (CoreBluetooth and NetworkExtension). These observations are critical for optimizing our app's performance, and I would appreciate any official guidance or documentation references.
CoreBluetooth Scanning Frequency and Cycle
Issue:
We noticed inconsistent BLE device discovery times (ranging from 0.5s to 1.5s) despite the peripheral advertising at 2Hz (500ms interval).
Questions:
Does iOS regulate the BLE scan interval or duty cycle internally? If yes, what factors affect this behavior (e.g., foreground/background state, connected devices)?
Are there recommended practices to reduce discovery latency for peripherals with fixed advertising intervals?
Is there a way to configure scan parameters (e.g., scan window/interval) programmatically, similar to Android's BluetoothLeScanner?
Test Context:
Device: iPhone 13 mini (iOS 17.6.1)
Code: CBCentralManager.scanForPeripherals(withServices: nil, options: [CBCentralManagerScanOptionAllowDuplicatesKey: true])
NEHotspotConfigurationManager Workflow and Latency
Issue:
Using NEHotspotConfigurationManager.shared.apply(_:) to connect to Wi-Fi occasionally takes up to 8 seconds to complete.
Questions:
What is the internal workflow of the apply method? Does it include user permission checks, SSID scanning, authentication, or IP assignment steps?
Are there known scenarios where this method would block for extended periods (e.g., waiting for user interaction, network timeouts)?
Is the latency related to system-level retries or radio coexistence with other wireless activities (e.g., Bluetooth)?
Test Context:
Configuration: NEHotspotConfiguration(ssid: "TestSSID")
Behavior: Delay occurs even when the Wi-Fi network is in range and credentials are correct.
Hi, when I perform an overlay installation via a PKG on macOS for an application containing the NEFilterDataProvider functionality, there is a chance that the entire system network becomes unreachable. Disabling the corresponding Content Filter in "System Settings > Network > Filters" immediately restores network connectivity. This issue does not occur every time, with a frequency of approximately 1 in 20 installation attempts.
The following details may help identify the problem:
The Filter.app containing the NEFilterDataProvider resides within the main app's Resources directory, e.g., /Applications/Main.app/Contents/Resources/Filter.app
Main.app is installed via a PKG; the issue typically occurs during an overlay installation of Main.app.
The NEFilterDataProvider operates as a System Extension.
The func handleNewFlow(_ flow: NEFilterFlow) -> NEFilterNewFlowVerdict {} returns .allow.
Wireshark packet captures show TCP packets but no UDP packets; TCP handshakes cannot complete.
Disabling the corresponding content filter in "System Settings > Network > Filters" restores the network; re-enabling it breaks connectivity again.
After waiting for a period, approximately 30-60 minutes, network connectivity can recover automatically.
What causes this and how can it be fixed? Any workarounds?
I am developing an App based on Network Extension that lets all network requests on device access the Internet through a private Relay.
I created an empty iOS App and only the entitlements file and ViewController.swift(Main.storyboard) file have been modified. The code was copied from the official video https://developer.apple.com/videos/play/wwdc2023/10002/
But, running the App on iPhone, the saveToPreferences API reported Error Domain=NERelayErrorDomain Code=3 "(null)" and the App doesn't look like it's changed at all (it doesn't jump to the Settings - VPN&Relay). Does anyone know why?Any reply would be greatly appreciated.
The contents of the entitlements file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>com.apple.developer.networking.networkextension</key>
<array>
<string>relay</string>
</array>
</dict>
</plist>
ViewController.swift:
import UIKit
import NetworkExtension
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
@IBAction func tap(_ sender: Any) {
let newRelay = NERelay()
let relayURL = URL(string: "https://relay.example.com:443/")
newRelay.http3RelayURL = relayURL
newRelay.http2RelayURL = relayURL
newRelay.additionalHTTPHeaderFields = ["Authorization" : "PrivateToken=123"]
let manager = NERelayManager.shared()
manager.relays = [newRelay]
manager.matchDomains = ["internal.example.com"]
manager.isEnabled = false
manager.saveToPreferences { err in
print(err)
}
}
}
We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt.
After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted.
Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot.
This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems...
The issues started from macOS Sequoia 15.0
By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file
Removing the following plist in Recovery Mode seems to resolve the issue
rm "/Volumes/Macintosh HD/Library/Preferences/com.apple.networkextension.plist"
Is this safe to do?
Topic:
App & System Services
SubTopic:
Networking
We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt.
After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted.
Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot.
This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems...
The issues started from macOS Sequoia 15.0
By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file
We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt.
After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted.
Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot.
This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems...
The issues started from macOS Sequoia 15.0
By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file
Removing the following plist in Recovery Mode seems to resolve the issue
rm "/Volumes/Macintosh HD/Library/Preferences/com.apple.networkextension.plist"
Is this safe to do?
Topic:
App & System Services
SubTopic:
Networking
Hi all!
I’m having trouble distributing an iOS app with a DNS Proxy NetworkExtension via AdHoc. The app and extension work perfectly with development profiles, but when I export and install the AdHoc IPA, I get a “permission denied” error when trying to install/enable the DNS Proxy extension.
What I’ve done:
Both the app and the DNS Proxy extension have their own App IDs in the Apple Developer portal.
Both App IDs have the same App Group enabled: group.com.irakai.SafeLinkApp2.
The extension App ID has the NetworkExtension capability with dns-proxy enabled.
I created two AdHoc provisioning profiles (one for the app, one for the extension), both including the same devices and the correct entitlements.
I assigned the correct AdHoc profiles to each target in Xcode and exported the IPA via Organizer.
I install the IPA on a registered device using Apple Configurator.
Entitlements (extracted from the signed binaries on device):
App:
<key>application-identifier</key><string>6PBG234246.com.irakai.SafeLinkApp2</string>
<key>com.apple.developer.networking.networkextension</key><array>
<string>packet-tunnel-provider</string>
<string>dns-proxy</string>
</array>
<key>com.apple.developer.team-identifier</key><string>6PBG234246</string>
<key>com.apple.security.application-groups</key><array>
<string>group.com.irakai.SafeLinkApp2</string>
</array>
<key>get-task-allow</key><false/>
DNSProxy Extension:
<key>application-identifier</key><string>6PBG234246.com.irakai.SafeLinkApp2.DNSProxy</string>
<key>com.apple.developer.networking.networkextension</key><array>
<string>dns-proxy</string>
</array>
<key>com.apple.developer.team-identifier</key><string>6PBG234246</string>
<key>com.apple.security.application-groups</key><array>
<string>group.com.irakai.SafeLinkApp2</string>
</array>
<key>get-task-allow</key><false/>
Error message (from my app’s logs):
Error instalando DNS Proxy: permission denied
Usuario: Roberto
AppGroup: group.com.irakai.SafeLinkApp2
AppGroupPath: /private/var/mobile/Containers/Shared/AppGroup/D8AD2DED-AD96-4915-9B7A-648C9504679B
Entitlements:
BundleId: com.irakai.SafeLinkApp2
Debug info: Error Domain=NEDNSProxyErrorDomain Code=1 "permission denied" UserInfo={NSLocalizedDescription=permission denied}
Other details:
The device is included in both AdHoc profiles.
The App Group is present and identical in both entitlements.
The extension’s bundle identifier matches the App ID in the portal.
The extension is signed with the correct AdHoc profile.
I have tried rebooting the device and reinstalling the IPA.
The error only occurs with AdHoc; development builds work fine.
Questions:
Is there anything else I should check regarding AdHoc provisioning for NetworkExtension DNS Proxy?
Are there any known issues with AdHoc and NetworkExtension on recent iOS versions?
Is there a way to get more detailed diagnostics from the system about why the permission is denied?
Could this be a bug in iOS, or am I missing a subtle configuration step?
Any help or suggestions would be greatly appreciated.
Thank you!
I was wondering which is the preferred way to send a lot of data from sensors of the apple watch to server.
It is preferred to send small chucks to iphone and then to server or directly send bulk data to server from watch. How does it affect battery and resources from watch ?
Are there any triggers that I can use to ensure best data stream. I need to send at least once a day. Can I do it in background or do I need the user to have my app in the foreground ?
Thank you in advance
Topic:
App & System Services
SubTopic:
Networking
Tags:
WatchKit
Health and Fitness
Network
Apple Watch
Question: Best Practice for NEFilterRule and NENetworkRule Initializers with Deprecated NEHostEndpoint?
Hi all,
I'm looking for guidance on the right way to construct an NEFilterRule that takes a NENetworkRule parameter. Reading the latest documentation, it looks like:
All initializers for NENetworkRule that accept an NEHostEndpoint are now deprecated, including initWithDestinationHost:protocol: and those using the various *Network:prefix: forms. NEHostEndpoint itself is also deprecated; Apple recommends using the nw_endpoint_t type from the Network framework instead.
However, NEFilterRule still requires a NENetworkRule for its initializer (docs).
With all NENetworkRule initializers that take NEHostEndpoint deprecated, it’s unclear what the recommended way is to create a NENetworkRule (and thus an NEFilterRule) that matches host/domain or network traffic.
What’s the proper way to construct these objects now—should we create the endpoints using nw_endpoint_t and use new/undocumented initializers, or is there an updated approach that’s considered best practice?
Helpful doc links for reference:
NEFilterRule docs
NENetworkRule docs
NWHostEndpoint (now deprecated)
Hello,
I have been implementing NEAppPushProvider class to establish my own protocol to directly communicate with our provider server without the need to rely on APNs for background push notifications.
I am at a stage where I am able to establish a tcp communicator and receive messages back and forth but I noticed that when I disconnect from the WIFI I've set up by setting a given SSID, I am not getting hit on the Stop method. Below is briefly how I load and save preferences.
NEAppPushManager appPushManager = new NEAppPushManager();
appPushManager.LoadFromPreferences((error) =>
{
if (error != null)
{
Console.WriteLine($"Error loading NEAppPushManager preferences: {error.LocalizedDescription}");
return;
}
if (!enable)
{
Console.WriteLine("Disabling Local Push Provider...");
appPushManager.Enabled = false;
// ✅ Immediately update UserDefaults before saving preferences
userDefaults.SetBool(false, Constants.IsLocalPushEnabled);
userDefaults.Synchronize();
appPushManager.SaveToPreferences((saveError) =>
{
if (saveError != null)
{
Console.WriteLine($"Error disabling Local Push: {saveError.LocalizedDescription}");
}
else
{
Console.WriteLine("Local Push successfully disabled.");
}
});
return;
}
// ✅ Now we can safely enable Local Push
Console.WriteLine($"Enabling Local Push for SSID: {_currentSSID}");
appPushManager.MatchSsids = new string[] { _currentSSID };
appPushManager.LocalizedDescription = "LocalPushProvider";
appPushManager.ProviderBundleIdentifier = Constants.LocalPushExtensionBundleId;
appPushManager.Enabled = true;
appPushManager.SaveToPreferences((saveError) =>
{
if (saveError != null)
{
Console.WriteLine($"Error saving Local Push settings: {saveError.LocalizedDescription}");
}
else
{
Console.WriteLine("✅ Local Push successfully registered.");
userDefaults.SetBool(true, Constants.IsLocalPushEnabled);
userDefaults.Synchronize();
}
});
});
I've read through documentation and was expecting the Stop method to be hit when I turn off Wifi. Am I missing anything? Please let me know if I should provide more info. Currently I just have a console writeline method inside the Stop method to see if it actually gets hit.
This is the log on the publisher side.
Publisher discovered the subscriber, but could not pair.
Follow up is sent with response rejected
Question:
What is the standard, most reliable way to manage temporary files associated with a URLSessionDownloadTask that has been terminated abnormally due to a network error or other issues?
Details
Hello,
I'm currently developing a feature to download multiple files concurrently on iOS using URLSessionDownloadTask, and I have a question regarding the lifecycle of the temporary files created during this process.
As I understand it, URLSessionDownloadTask stores incoming data in a temporary file within the tmp directory, typically with a name like CFNetworkDownload_*.tmp.
In my testing, temporary files are managed correctly in the normal scenario. For instance, when I call the cancel() method on an active downloadTask and then release all references to it, the corresponding temporary file is automatically cleaned up from the tmp directory shortly after.
However, the problem occurs when a download is interrupted abnormally due to external factors, such as a lost network connection. In this situation, the urlSession(_:task:didCompleteWithError:) delegate method is called, but the associated temporary file is not deleted and remains in the tmp directory.
I've observed a particularly interesting behavior related to this. Immediately after the error occurs, if I check my app's storage usage in the iOS Settings app, the data size appears to have decreased momentarily. However, the tmp file has not actually been deleted, and after a short while, the storage usage is recalculated to include the size of this orphaned temporary file.
Since my app does not support resuming interrupted downloads, these leftover files become orphaned and unnecessarily consume storage. Therefore, I want to ensure they are all reliably deleted.
With this context, I'd like to ask the community:
What is the standard, most reliable way to manage temporary files associated with a URLSessionDownloadTask that has been terminated abnormally due to a network error or other issues?
I am wondering if there is an official guide or a framework-level API to handle these orphaned files.
I would appreciate any advice from those with experience in this area. Thank you.
Hi there, I am working on an app that configures a PacketTunnelProvider to establish a VPN connection. Unfortunately, while a VPN connection is established, I am unable to update the app via testflight. Downloading other app updates works fine.
I noticed that after I receive the alert that updating failed, the vpn badge appears at the top of my screen (the same ux that occurs when the connection is first established). So it's almost like it tried to close the tunnel, and seeing that the app update failed it restablishes the tunnel.
I am unsure of why I would not be able to update my app. Maybe stopTunnel is not being called with NEProviderStopReason.appUpdate?
Could anyone tell me how to detect status of Local Network for iOS 18+ systems ?
Hi everyone, I developed an Android version of a VPN app built with Flutter using OpenVPN, and it works perfectly on Android. However, when porting it to iOS, I’ve encountered an issue: the app connects successfully but then automatically disconnects when tested via TestFlight. We’ve already added all the necessary network extensions. Despite this, we decided to submit the app to the App Store. It’s been five days now, and the app is still 'Waiting for Review.' Could anyone share their experience deploying and working on an iOS version of a VPN app? I’d really appreciate your insights!
I am developing an Xcode app with a job feed, with profile view, with chat eg. I fetch using federatet queries to my microservices thru Apollo Router. Infront of the Apollo Router i Have a Kong that adds a X user ID, that the microservices use for personalized feed and other user info. The info is stored with SwiftData. My thought is that i should add a better way of controlling when i need to fetch. I have a “lastupdateAPI” with different entities (profile, profile picture eg). So when nothing has changed we do not fetch. But rather then using a own API for this, isnt ETag better? Or is it any other recommendations with Xcode Swiftui. Good strategies for not fetching what i already have?
Topic:
App & System Services
SubTopic:
Networking
My app sent a network request to the backend. The backend returns a 200, but the front end received a -1001 or -1005 NSURLError. Any clue why this could be happening?