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Networking Documentation

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startProxy delegate for NETransparentProxyProvider class is being called twice for the same pid extension sometimes
We have an application which is written in Swift, which activates Transparent Proxy network 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.) Sometimes we have observed that on starting the transparent proxy extension, the startProxy overridden delegate method(override func startProxy(options: [String : Any]?, completionHandler: @escaping (Error?) -> Void) {) in our AppProxyProvider class which is derived from NETransparentProxyProvider being called more than once for the same extension(pid). This leads to Over-resume of an object crash as we invoke setTunnelNetworkSettings inside the startProxy delegate. As this is controlled by the system, we are not sure why this delegate being called more than once sometimes even if we call the start TransparentProxy only once. Note that, this issue is seen only in Mac OS Tahoe. Apple Feedback ticket: FB21464147 (startProxy delegate for NETransparentProxyProvider class is being called twice for the same pid extension sometimes)
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4w
WiFi Aware connection cannot be established when both peers publish and subscribe
It works when one device is only a publisher and the other is only a subscriber. However, when both devices act as both publisher and subscriber simultaneously—which Apple’s documentation (https://developer.apple.com/documentation/wifiaware/adopting-wi-fi-aware#Declare-services) indicates is valid—the connection never establishes. After timing out, both NetworkListener and NetworkBrowser transition to the failed state. This appears to be a race condition in Network framework. Task.detached { try await NetworkListener( for: .wifiAware( .connecting( to: .myService, from: .allPairedDevices, datapath: .defaults ) ), using: .parameters { Coder( sending: ..., receiving: ..., using: NetworkJSONCoder() ) { TCP() } } ).run { connection in await self.add(connection: connection) } } Task.detached { try await NetworkBrowser( for: .wifiAware( .connecting( to: .allPairedDevices, from: .myService ) ), using: .tcp ).run { endpoints in for endpoint in endpoints { await self.connect(to: endpoint) } } }
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108
4w
Sporadic "no route to host" over ssh
When connecting to my M1 mac mini over ssh, certain programs are often unable to reach network destinations in the corporate LAN, although they can usually reach external addresses like www.apple.com. For example, a java program attempting to download from teamcity.dev.corp.com:8111 often fails like: java.net.NoRouteToHostException: No route to host Running the exact same command from the Apple Terminal program works like normal, simply connecting over ethernet on en0 to a TeamCity server inside the same building. Basic diagnostics from the ssh session do not show anything unusual: > traceroute teamcity.dev.corp.com traceroute to teamcity.dev.corp.com (10.21.4.1), 64 hops max, 40 byte packets 1 teamcity.dev.corp.com (10.21.4.1) 1.702 ms 0.409 ms 0.336 ms > route -n get teamcity.dev.corp.com route to: 10.21.4.1 destination: 10.21.4.1 interface: en0 flags: <UP,HOST,DONE,LLINFO,WASCLONED,IFSCOPE,IFREF> recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire 0 0 0 0 0 0 1500 1194 > uname -a Darwin mac 25.1.0 Darwin Kernel Version 25.1.0: Mon Oct 20 19:32:47 PDT 2025; root:xnu-12377.41.6~2/RELEASE_ARM64_T8103 arm64 Similar problems occur in docker commands to a remote daemon ("no route to host" or "connection refused"): docker -H tcp://<ip>:<port> ... Most other programs are never affected by this problem. Are there other diagnostic steps that might reveal the cause?
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109
Jan ’26
Local network request blocked in Safari but working in Chrome
For Local network access, Chrome prompts the user to allow access and adds it to Settings --> Privacy & Security --> Local Network. However, for Safari, no prompt appears. How do I force Safari to authorise these local network access requests if it won't trigger the permission dialogue? Is there a specific WKWebView configuration or Safari-specific header required to satisfy this security check?
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473
Jan ’26
VPN profile corruption
We've often observed connectivity issues from our VPN app that can only be remedied by removing the VPN profile. It happens to a small but significant amount of our users, this often happens more when the app is updated, but the VPN profile corruption can happen without that too. The behavior we're observing is that any socket opened by the packet tunnel process just fails to send any data whatsoever. Stopping and restarting the packet tunnel does not help. The only solution is to remove the profile and create a new one. We believe our app is not the only one suffering from this issue as other VPN apps have added a specific button to refresh their VPN profile, which seemingly deletes and re-created the VPN configuration profile. Previously, we've caught glimpses of this in a sysdiagnose, but that was a while ago and we found nothing of interest. Alas, the sysdiagnose was not captured on a device with the network extension diagnostic profile (it was not a developer device). I would love to get technical support with this, as our bug reports have gone unanswered for long enough, yet we are still struggling with this issue. But of course, there is no minimum viable xcodeproject that reproduces this. Is there anything we can feasibly do to help with this issue? Is it even an acknowledged issue?
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268
Dec ’25
ipad通过转接口连接上有线网络之后,部分设备无法获取到IP地址
private static func getEthernetIPAddress(from interfaces: [String: String]) -> String? { // 常见虚拟以太网接口名(根据适配器型号可能不同) let poeEthernetInterfaces = ["en2", "en3", "en4", "en5", "eth0", "eth1"] for interfaceName in poeEthernetInterfaces { if let ethernetIP = interfaces[interfaceName], !ethernetIP.isEmpty { return ethernetIP } } return nil }//我们通过该方法去抓取有线网的IP地址,但是有的设备无法抓取到,怎样才能更准确的抓取到有线网络的IP地址
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125
Dec ’25
Once started, NWPathMonitor appears to be kept alive until cancelled, but is this documented?
NWPathMonitor appears to retain itself (or is retained by some internal infrastructure) once it has been started until cancelled. This seems like it can lead to memory leaks if the references to to the monitor are dropped. Is this behavior documented anywhere? func nwpm_self_retain() { weak var weakRef: NWPathMonitor? autoreleasepool { let monitor: NWPathMonitor = NWPathMonitor() weakRef = monitor monitor.start(queue: .main) // monitor.cancel() // assertion fails unless this is called } assert(weakRef == nil) } nwpm_self_retain()
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129
Dec ’25
MultiPeer Connectivity: Device discovery succeeds but handshake fails when off-network
Hi, I am building an app that depends on multiple iOS devices connecting to a designated "coordinator" iOS device. I am using MPC, and it works great when the devices are connected to the same WiFi AP, with virtually 100% connection success. My definition of success is a near instant detection of available devices, >95% connection success rate, and a stable ongoing connection with no unexpected disconnects. The issue arises when the devices are not connected to the same WiFi network (or connected to no network with WiFi and bluetooth still on). Devices detect each other immediately, but when initiating a connection, both devices initiate a handshake, but the connection is not successful. In the few times where the connection succeeds, the connection quality is high, stable, and doesn't drop. Is this a known limitation of the framework? Could I be doing something wrong in my implementation?
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171
Dec ’25
`setTunnelNetworkSettings` errors in a packet tunnel provider.
We've received logs and have spuriously reproduced the following behavior: calls to setTunnelNetworkSettings completing with NETunnelProviderError where the code is networkSettingsInvalid, and the error domain string is empty. After subsequent calls to setTunnelNetworkSettings, the tunnel is stopped via the userInitiated stop reason within around 1 second from the first failure. This happens after a number of successful calls to setTunnelNetworkSettings have been made in the lifetime of a given packet tunnel process. We can confirm that no user ever initiates the disconnection. We can confirm that the only significant changes between the different calls to setTunnelNetworkSettings are that the parameters contain different private IPs for the tunnel settings - the routes and DNS settings remain the same. In our limited testing, it seems that we can replicate the behavior we're observing by removing the VPN profile while the tunnel is up. However, we are certain the same behavior happens under other circumstances without any user interaction. Is this what memory starvation looks like? Or is this something else? Our main concern is that the tunnel is killed and it is not brought back up even though our profile is set to be on-demand. It's difficult to give any promises about leaks to our users if the tunnel can be killed at any point and not be brought back. The spurious disconnections are a security issue for our app, we'd like to know if there's anything we can do differently so that this does not happen. We tried to get DTS, but given that we have no way to reproduce this issue with a minimal project. But we can reproduce the behavior (kill the tunnel by removing it's profile) from a minimal Xcode project, is that considered good enough for a reproduction?
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Dec ’25
Issues Generating Bloom Filters for Apple NetworkExtension URL Filtering
Hi there, We have been trying to set up URL filtering for our app but have run into a wall with generating the bloom filter. Firstly, some context about our set up: OHTTP handlers Uses pre-warmed lambdas to expose the gateway and the configs endpoints using the javascript libary referenced here - https://developers.cloudflare.com/privacy-gateway/get-started/#resources Status = untested We have not yet got access to Apples relay servers PIR service We run the PIR service through AWS ECS behind an ALB The container clones the following repo https://github.com/apple/swift-homomorphic-encryption, outside of config changes, we do not have any custom functionality Status = working From the logs, everything seems to be working here because it is responding to queries when they are sent, and never blocking anything it shouldn’t Bloom filter generation We generate a bloom filter from the following url list: https://example.com http://example.com example.com Then we put the result into the url filtering example application from here - https://developer.apple.com/documentation/networkextension/filtering-traffic-by-url The info generated from the above URLs is: { "bits": 44, "hashes": 11, "seed": 2538058380, "content": "m+yLyZ4O" } Status = broken We think this is broken because we are getting requests to our PIR server for every single website we visit We would have expected to only receive requests to the PIR server when going to example.com because it’s in our block list It’s possible that behind the scenes Apple runs sporadically makes requests regardless of the bloom filter result, but that isn’t what we’d expect We are generating our bloom filter in the following way: We double hash the URL using fnv1a for the first, and murmurhash3 for the second hashTwice(value: any, seed?: any): any { return { first: Number(fnv1a(value, { size: 32 })), second: murmurhash3(value, seed), }; } We calculate the index positions from the following function/formula , as seen in https://github.com/ameshkov/swift-bloom/blob/master/Sources/BloomFilter/BloomFilter.swift#L96 doubleHashing(n: number, hashA: number, hashB: number, size: number): number { return Math.abs((hashA + n * hashB) % size); } Questions: What hashing algorithms are used and can you link an implementation that you know is compatible with Apple’s? How are the index positions calculated from the iteration number, the size, and the hash results? There was mention of a tool for generating a bloom filter that could be used for Apple’s URL filtering implementation, when can we expect the release of this tool?
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175
Dec ’25
Content filtering
Hello team, Would this mean that content filters intended for all browsing can only be implemented for managed devices using MDM? My goal would be to create a content filtering app for all users, regardless of if their device is managed/supervised. thanks.
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86
Dec ’25
FYI: Network System extension, macOS update issue, loss of networking
This is just an FYI in case someone else runs into this problem. This afternoon (12 Dec 2025), I updated to macOS 26.2 and lost my network. The System Settings' Wi-Fi light was green and said it was connected, but traceroute showed "No route to host". I turned Wi-Fi on & off. I rebooted the Mac. I rebooted the eero network. I switched to tethering to my iPhone. I switched to physical ethernet cable. Nothing worked. Then I remembered I had a beta of an app with a network system extension that was distributed through TestFlight. I deleted the app, and networking came right back. I had this same problem ~2 years ago. Same story: app with network system extension + TestFlight + macOS update = lost network. (My TestFlight build might have expired, but I'm not certain) I don't know if anyone else has had this problem, but I thought I'd share this in case it helps.
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147
Dec ’25
mDNSResponder: legacy OpenSSL licence
Hello, I’m reviewing the open-source mDNSResponder repository and have a question regarding licensing/provenance in mDNSCore/DNSDigest.c file. That file contains an embedded notice stating that parts of the MD5/digest implementation were derived from older OpenSSL sources and therefore include the legacy OpenSSL/SSLeay license text, even though OpenSSL itself is now Apache-2.0 starting from version 3.0. The legacy OpenSSL/SSLeay license is widely understood to impose additional attribution and notice requirements compared to Apache-2.0, and some downstream projects prefer to avoid it when a permissively licensed alternative is available. Repository: https://github.com/apple-oss-distributions/mDNSResponder File: https://github.com/apple-oss-distributions/mDNSResponder/blob/main/mDNSCore/DNSDigest.c#L66 I’d like to clarify a few points: Is the MD5/digest code in DNSDigest.c still based on pre–OpenSSL-3.0 sources, such that retaining the legacy OpenSSL/SSLeay license block is intentional and required? If the goal were to simplify licensing (Apache-2.0 only), would Apple consider replacing this MD5 implementation with an Apache-2.0–licensed alternative (for example, code derived from OpenSSL 3.x or another permissive implementation)? Are there any technical or policy reasons (compatibility, crypto policy, platform APIs) that make such a replacement undesirable? Since GitHub issues and PRs are restricted for this repository, I’m asking here for guidance. If maintainers agree that such an update would be useful, I’d be happy to help by preparing a PR for review. I've also created a feedback report for this topic, the reference ID is FB21269078. Thanks for any clarification.
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140
Dec ’25
macOS Network Extension deactivation fails with authorizationRequired
Hello, I have a .app that runs as LaunchDaemon and configured to be an Agent (LSUIElement) that is stored in /Applications. Installing network extensions works, but deactivation fails with OSSystemExtensionErrorDomain error 13 (authorization required). requestNeedsUserApproval is not called for deactivation, but it's called when being activated. Any ideas? Thank you! P.S. It works on Debug, just not on Release...
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175
Dec ’25
Content & URL filtering
Hello team, I am developing a security app where I am denying certain flows/packets if the are communicating with known malicious endpoints. Therefore I want to make use of NetworkExtensions such as the new URLFilter or ContentFilter (NEURLFilterManager, NEFilterDataProvider, NEFilterControlProvider). Does NEURLFilterManager require the user's device to be at a minimun of ios 26? Does any of these APIs/Extensions require the device to be managed/supervised or can it be released to all consumers? Thanks,
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132
Dec ’25
How to set the custom DNS with the Network client
We are facing a DNS resolution issue with a specific ISP, where our domain name does not resolve correctly using the system DNS. However, the same domain works as expected when a custom DNS resolver is used. On Android, this is straightforward to handle by configuring a custom DNS implementation using OkHttp / Retrofit. I am trying to implement a functionally equivalent solution in native iOS (Swift / SwiftUI). **Android Reference (Working Behavior) : ** val dns = DnsOverHttps.Builder() .client(OkHttpClient()) .url("https://cloudflare-dns.com/dns-query".toHttpUrl()) .bootstrapDnsHosts(InetAddress.getByName("1.1.1.1")).build() OkHttpClient.Builder().dns(dns).build() **Attempted iOS Approach ** I attempted the following approach : Resolve the domain to an IP address programmatically (using DNS over HTTPS) Connect directly to the resolved IP address Set the original domain in the Host HTTP header **DNS Resolution via DoH : ** func resolveDomain(domain: String) async throws -> String { guard let url = URL( string: "https://cloudflare-dns.com/dns-query?name=\(domain)&type=A" ) else { throw URLError(.badURL) } var request = URLRequest(url: url) request.setValue("application/dns-json", forHTTPHeaderField: "accept") let (data, _) = try await URLSession.shared.data(for: request) let response = try JSONDecoder().decode(DNSResponse.self, from: data) guard let ip = response.Answer?.first?.data else { throw URLError(.cannotFindHost) } return ip } **API Call Using Resolved IP : ** func callAPIUsingCustomDNS() async throws { let ip = try await resolveDomain(domain: "example.com") guard let url = URL(string: "https://\(ip)") else { throw URLError(.badURL) } let configuration = URLSessionConfiguration.ephemeral let session = URLSession( configuration: configuration, delegate: CustomURLSessionDelegate(originalHost: "example.com"), delegateQueue: .main ) var request = URLRequest(url: url) request.setValue("example.com", forHTTPHeaderField: "Host") let (_, response) = try await session.data(for: request) print("Success: \(response)") } **Problem Encountered ** When connecting via the IP address, the TLS handshake fails with the following error: Error Domain=NSURLErrorDomain Code=-1200 "A TLS error caused the secure connection to fail." This appears to happen because iOS sends the IP address as the Server Name Indication (SNI) during the TLS handshake, while the server’s certificate is issued for the domain name. **Custom URLSessionDelegate Attempt : ** class CustomURLSessionDelegate: NSObject, URLSessionDelegate { let originalHost: String init(originalHost: String) { self.originalHost = originalHost } func urlSession( _ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void ) { guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust, let serverTrust = challenge.protectionSpace.serverTrust else { completionHandler(.performDefaultHandling, nil) return } let sslPolicy = SecPolicyCreateSSL(true, originalHost as CFString) let basicPolicy = SecPolicyCreateBasicX509() SecTrustSetPolicies(serverTrust, [sslPolicy, basicPolicy] as CFArray) var error: CFError? if SecTrustEvaluateWithError(serverTrust, &error) { completionHandler(.useCredential, URLCredential(trust: serverTrust)) } else { completionHandler(.cancelAuthenticationChallenge, nil) } } } However, TLS validation still fails because the SNI remains the IP address, not the domain. I would appreciate guidance on the supported and App Store–compliant way to handle ISP-specific DNS resolution issues on iOS. If custom DNS or SNI configuration is not supported, what alternative architectural approaches are recommended by Apple?
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237
Dec ’25
How to set the custom DNS with the Network client
We are facing a DNS resolution issue with a specific ISP, where our domain name does not resolve correctly using the system DNS. However, the same domain works as expected when a custom DNS resolver is used. On Android, this is straightforward to handle by configuring a custom DNS implementation using OkHttp / Retrofit. I am trying to implement a functionally equivalent solution in native iOS (Swift / SwiftUI). Android Reference (Working Behavior) : val dns = DnsOverHttps.Builder() .client(OkHttpClient()) .url("https://cloudflare-dns.com/dns-query".toHttpUrl()) .bootstrapDnsHosts(InetAddress.getByName("1.1.1.1")) .build() OkHttpClient.Builder() .dns(dns) .build() Attempted iOS Approach I attempted the following approach : Resolve the domain to an IP address programmatically (using DNS over HTTPS) Connect directly to the resolved IP address Set the original domain in the Host HTTP header DNS Resolution via DoH : func resolveDomain(domain: String) async throws -> String {     guard let url = URL(         string: "https://cloudflare-dns.com/dns-query?name=\(domain)&type=A"     ) else {         throw URLError(.badURL)     }     var request = URLRequest(url: url)     request.setValue("application/dns-json", forHTTPHeaderField: "accept")     let (data, _) = try await URLSession.shared.data(for: request)     let response = try JSONDecoder().decode(DNSResponse.self, from: data)     guard let ip = response.Answer?.first?.data else {         throw URLError(.cannotFindHost)     }     return ip } API Call Using Resolved IP :  func callAPIUsingCustomDNS() async throws {     let ip = try await resolveDomain(domain: "example.com")     guard let url = URL(string: "https://(ip)") else {         throw URLError(.badURL)     }     let configuration = URLSessionConfiguration.ephemeral     let session = URLSession(         configuration: configuration,         delegate: CustomURLSessionDelegate(originalHost: "example.com"),         delegateQueue: .main     )     var request = URLRequest(url: url)     request.setValue("example.com", forHTTPHeaderField: "Host")     let (_, response) = try await session.data(for: request)     print("Success: (response)") } Problem Encountered When connecting via the IP address, the TLS handshake fails with the following error: Error Domain=NSURLErrorDomain Code=-1200 "A TLS error caused the secure connection to fail." This appears to happen because iOS sends the IP address as the Server Name Indication (SNI) during the TLS handshake, while the server’s certificate is issued for the domain name. Custom URLSessionDelegate Attempt :  class CustomURLSessionDelegate: NSObject, URLSessionDelegate {     let originalHost: String     init(originalHost: String) {         self.originalHost = originalHost     }     func urlSession(         _ session: URLSession,         didReceive challenge: URLAuthenticationChallenge,         completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void     ) {         guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust,               let serverTrust = challenge.protectionSpace.serverTrust else {             completionHandler(.performDefaultHandling, nil)             return         }         let sslPolicy = SecPolicyCreateSSL(true, originalHost as CFString)         let basicPolicy = SecPolicyCreateBasicX509()         SecTrustSetPolicies(serverTrust, [sslPolicy, basicPolicy] as CFArray)         var error: CFError?         if SecTrustEvaluateWithError(serverTrust, &error) {             completionHandler(.useCredential, URLCredential(trust: serverTrust))         } else {             completionHandler(.cancelAuthenticationChallenge, nil)         }     } } However, TLS validation still fails because the SNI remains the IP address, not the domain. I would appreciate guidance on the supported and App Store–compliant way to handle ISP-specific DNS resolution issues on iOS. If custom DNS or SNI configuration is not supported, what alternative architectural approaches are recommended by Apple?
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222
Dec ’25