I had noticed that my slaac address changed between one beta and the other, but wasn't sure. Now with the RC 15.4 RC (24E247) I made point of preserving the info before updating from the previous beta. What I noticed is that not only the slaac address changes, but also the my ether address, even though I have it on Fixed in the settings. Is it expected that the ether, and the slaac, not be rotated after a OS update?

On Sequoia it became impossible to properly debug programs using third party mDNS, multicast or broadcast, thanks to a bug? in I guess the new local network privacy feature, every send call returns no route to host. If I run the CI job, which properly packages, signs, notarizes said program, the resulting .app works fine and also requests permission to access the local network - which is impossible through lldb as it doesn't have an Info.plist, just the ***** binary itself. However this may not be the issue, see the repro method below. A fast and easy method to reproduce is using an example from this repo: https://github.com/keepsimple1/mdns-sd/ Running the query example in a good old shell without lldb (cargo run --example query _smb._tcp) starts outputting results. Then running the same binary through lldb (lldb -o run target/debug/examples/query _smb._tcp) would result in no route to host errors. I can't provide an output anymore as I was forced to downgrade. It works fine again on 14.6.1. I'm a bit reluctant to even try 14.7. Also reported in feedback assistant: FB15185667

We are migrating our iOS app to macOS. On iOS, it works fine. But when I try and run on macOS and connect to the VPN, I am getting an error like failed to fetch /Users/stuart/Library/Developer/Xcode/DerivedData/app-byzvshkqegwzqxgervfswmsughkm/Build/Products/Debug/<app_name>.app/Contents/PlugIns/<network_extension_name>.appex/Contents/_CodeSignature/CodeRequirements-1 error=-10. If I have Settings -> VPN open, it rapidly is connecting and disconnecting. Is there anything I need to do specific to macOS to make this work? Or is this related to a broken code signature? Thanks in advance!

Hey,I want to get nearby Wi-Fi network's SSID into the app using network extension framework.Right now I can get scan list by visiting the setting---&amp;gt;Wifi Screen but I want to get those Scan Result into the app without visiting the setting wifi screen.If anyone idea about it please let me know

It doesn’t seem like there’s any high level, first-party documentation on how to use what is the recommended API for executing networking logic that you otherwise wouldn’t use URLSession for; which is a lot of things. There’s a sample app, and docs on how to choose the right network API in general, but apparently no high level API docs for Network.framework itself. Am I missing something? How do people learn to use this? Know which classes to use? Know the various ways it can be configured?

Hi, TLDR: On iOS, when my PacketTunnel is running, can I exclude DNS requests from going into the tunnel? I have a test app, using Apple's AsyncDNSResolver, that makes a DNS call and it works when the tunnel is not running. If the tunnel is running it times out after 30 seconds and I get the error -65568. Here's how I'm setting up the tunnel func setup(tunnelRemoteAddress: String) { let settings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: tunnelRemoteAddress) settings.ipv4Settings = NEIPv4Settings(addresses: [tunnelRemoteAddress], subnetMasks: ["255.255.255.255"]) settings.ipv4Settings?.includedRoutes = [NEIPv4Route.default()] let proxySettings = NEProxySettings() proxySettings.httpEnabled = true proxySettings.httpServer = NEProxyServer(address: ProxyServerConfiguration.host, port: ProxyServerConfiguration.port) proxySettings.httpsEnabled = true proxySettings.httpsServer = NEProxyServer(address: LocalProxyServerConfiguration.host, port: LocalProxyServerConfiguration.port) proxySettings.excludeSimpleHostnames = true proxySettings.exceptionList = nil let dnsSettings = NEDNSSettings(servers: ["8.8.8.8"]) settings.dnsSettings = dnsSettings settings.proxySettings = proxySettings setTunnelNetworkSettings(settings) { error in // ... } } I've tried all combinations of setting/excluding the NEDNSSettings but the DNS call always fails when the tunnel is running. Thanks for any help.

So I have a small homebuilt device that has a simple Arduino-like chip with wifi capabilities (to be precise, the Xiao Seeed ESP32C, for anyone who cares), and I need my iOS app to talk to this device. Using the CoreBluetooth framework, we've had no problems --- except that in "noisy" environments sometimes we have disconnects. So we want to try wifi. We assume that there is no public wifi network available. We'd love to do peer-to-peer networking using Network, but that's only if both devices are from Apple. They're not. Now, the Xiao device can act as an access point, and presumably I could put my iPhone on that network and use regular TCP calls to talk to it. The problem is that my app wants to both talk to this home-built device, but ALSO make http calls to my server an amazon. So: how do I let my iOS app talk over wifi to this simple chip, while not losing the ability to also have my app reach a general server (and receive push notifications, etc.) To be more concrete, imagine that my app needs to be able to discover the access point provided by my device, use low-level TCP socket calls to talk to this local wifi device, all without losing the ability to also make general http calls and be just accessible to push notifications as it was before connecting to this purely local (and very short range, i.e. no more than 30 meters distant) device. Does this make sense? Have I explained it well enough?

In my application, there is a Network Extension with the bundle ID com.***.agent.yyy.zzz.ne. There is a user upgraded their system to macOS Sequoia 15.3, they faced an issue where enabling this Network Extension failed. Even after uninstalling the application and the Network Extension, restarting the system, and reinstalling multiple times, the enabling process still failed. it alert: Failed to enable the Network Extension. When checking the status via "systemextension list", it always shows "activated waiting for user". This shows the normal enabling process log: This shows the log when the enabling fails upon clicking. Strangely enough, there is no activation operation log when it fails. What could be the problem?

If the includeAllNetworks flag to true, we cannot update our app via Xcode, TestFlight or the AppStore. In the AppStore and TestFlight cases, it seems that the packet tunnel process is stopped before the new app is downloaded - once the packet tunnel process is stopped, it can’t be started again via Settings/VPN profiles, nor can it be started via the app.

Hello, I am planning to create an app that can transfer files to hardware devices via WiFi. With devices like GoPro, I believe the typical setup involves the GoPro creating a WiFi hotspot to which the iOS app connects, allowing file transfers. But this setup establishes a 1:1 connection between the app and the hardware. To support multiple hardware devices simultaneously, I am considering reversing this setup: the iOS device would create a personal hotspot, and the hardware devices would connect to it. However, I have concerns about this approach: Reliability: I have read that the personal hotspot feature on iOS devices can be unreliable, especially with non-Apple devices, which tend to disconnect frequently. Manual Setup: There is no API to programmatically create the personal hotspot, so users would have to enable it manually in the Settings. I can use isIdleTimerDisabled to prevent the iOS screen from going to sleep, which might help with disconnection issues. Aside from this, are there other things I can do to ensure a stable connection? Given my limited experience with hardware connections, I am uncertain if having the iOS device act as the WiFi access point is a good design. Any advice or alternative solutions would be greatly appreciated. Thank you in advance!

I'm seeing behaviour that I'm struggling to work out when making GraphQL related network requests (these are POST requests). I note that QA1941 covers the "lost connection" errors that I see in my responses, but I'd like to understand more, because just retrying the connection without understanding why I need to seems problematic. Here's the (partially redacted) logs I see when the error occurs: quic_conn_keepalive_handler [C69.1.1.1:2] [-0178f8467262b9e978791446c6629ddb66b2efc1] keep-alive timer fired, exceeding 2 outstanding keep-alives nw_read_request_report [C69] Receive failed with error "Operation timed out" nw_read_request_report [C69] Receive failed with error "Operation timed out" nw_read_request_report [C69] Receive failed with error "Operation timed out" nw_read_request_report [C69] Receive failed with error "Operation timed out" nw_read_request_report [C69] Receive failed with error "Operation timed out" 0x16264d818 69 stalled, attempting fallback Task <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11> HTTP load failed, 1822/0 bytes (error code: -1005 [4:-4]) Task <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12> HTTP load failed, 1823/0 bytes (error code: -1005 [4:-4]) nw_endpoint_flow_fillout_data_transfer_snapshot copy_info() returned NULL Task <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11> finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x60000139bd50 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x60000a217340 [0x1e006f658]>{length = 16, capacity = 16, bytes = 0x100201bb646394820000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11>" ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://myserver.com/graphql, NSErrorFailingURLKey=https://myserver.com/graphql, _kCFStreamErrorDomainKey=4} Task <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12> finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x60000139afd0 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x60000a217340 [0x1e006f658]>{length = 16, capacity = 16, bytes = 0x100201bb646394820000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12>" ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://myserver.com/graphql, NSErrorFailingURLKey=https://myserver.com/graphql, _kCFStreamErrorDomainKey=4} GraphQL request query failed for query with hash: 6677767707705440859 with error: Networking.NetworkGraphQLService.Error.underlying(Apollo.URLSessionClient.URLSessionClientError.networkError(data: 0 bytes, response: nil, underlying: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x60000139afd0 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x60000a217340 [0x1e006f658]>{length = 16, capacity = 16, bytes = 0x100201bb646394820000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <3B0AAA67-3162-4F80-A930-D93F8A7EF1A4>.<12>" ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://myserver.com/graphql, NSErrorFailingURLKey=https://myserver.com/graphql, _kCFStreamErrorDomainKey=4})) GraphQL request query failed for query with hash: 148576198322832328 with error: Networking.NetworkGraphQLService.Error.underlying(Apollo.URLSessionClient.URLSessionClientError.networkError(data: 0 bytes, response: nil, underlying: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x60000139bd50 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x60000a217340 [0x1e006f658]>{length = 16, capacity = 16, bytes = 0x100201bb646394820000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <A6CC8D4D-83E1-4C61-96C7-BDDF2F04A35F>.<11>" ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://myserver.com/graphql, NSErrorFailingURLKey=https://myserver.com/graphql, _kCFStreamErrorDomainKey=4})) GraphQL request query starting for query with hash: -5824714640174886330 nw_connection_copy_connected_local_endpoint_block_invoke [C90] Connection has no local endpoint nw_connection_copy_connected_local_endpoint_block_invoke [C90] Connection has no local endpoint GraphQL request query succeeded for query with hash: -5824714640174886330 nw_read_request_report [C43] Receive failed with error "Operation timed out" nw_read_request_report [C43] Receive failed with error "Operation timed out" nw_read_request_report [C43] Receive failed with error "Operation timed out" nw_connection_add_timestamp_locked_on_nw_queue [C43] Hit maximum timestamp count, will start dropping events nw_endpoint_flow_fillout_data_transfer_snapshot copy_info() returned NULL I'd really appreciate any advice or insight that people might have — I can't reproduce this problem consistently, so I want to know more. Thanks!

We've been directed here by Quinn in DTS. We use multicast/broadcast messages extensively in our physical products for discovery purposes. If, for whatever reason, our customers cannot get this to work on their home Wi-Fi network, we advise that they connect to an iPhone hotspot to confirm behaviour and perform firmware updates as needed. As of iOS 18, we're seeing odd behaviour when using Personal Hotspot. Interestingly, we're also seeing that client devices connected to the Hotspot network are not showing a Subnet Mask in the Wi-Fi Details screen in the iOS Settings app - I don't know if that's related. We're also seeing that screen show an IP address of 192.0.0.2 for all client iPhones connected to an iPhone Hotspot. Getting more specific, we're seeing that multicast messages are no longer being received by clients when connected to an iPhone Hotspot where the iPhone running the hotspot is running iOS 18.0 or newer. By "multicast", I mean we're using a BSD socket to send data to 255.255.255.255 I've confirmed that our app has the multicast entitlement, the user has granted Local Network permission, and we've created a small sample app that demonstrates this behaviour perfectly - when connected to any other test network, multicast messages are received correctly by clients. We've also confirmed that this behaviour doesn't happen when the iPhone running the hotspot is running older iOS versions. We've tried a number of iOS 17.x releases and a number of iOS 16.x releases specifically with our sample app, but have been using this exact code since our app's original iOS 9 deployment target and have had no issues until now.

Hi, I upgraded my MacOs to 15.0. I work with maven in my environment. Normally, while running tests with maven in my environment in Sonomo 14.5, I was connecting to my test database environment with the postgresql library in the background. But after the upgrade, I realized that maven could not do this. After some research, I saw that this policy for applications was newly added at https://support.apple.com/en-us/121011. So, starting from 15.0, we have to allow "Local Network" usage for each application. But when I run the "mvn test" command from the terminal, it does not ask me if I allow Local Network usage and that's why my mvn test gets an error. But in normal applications, the same transaction works differently; For example, if I use the terminal of VSCode.app, it pops up a popup asking if I allow it and I allow it. Then, I see that this application has been added under Local Network. I definitely think there is a bug here. Even though I allowed the postgresql jdbc driver with the "socketfilterfw" command, it doesn't work. Even though I allowed maven, it doesn't come under "Local Network applications". 1- Here, there definitely needs to be an option to add an application to the "Local Network" screen. 2- We need to define the "Local Network" usage authorization for all my applications or the relevant user with a single permission. The worst part here is for CI servers. There are too many application runtimes in CI. It is unnecessary to bother with authorizing all of them here.

Our product (rockhawk.ca) uses the Multipeer Connectivity framework for peer-to-peer communication between multiple iOS/iPadOS devices. My understanding is that MC framework communicates via three methods: 1) infrastructure wifi (i.e. multiple iOS/iPadOS devices are connected to the same wifi network), 2) peer-to-peer wifi, or 3) Bluetooth. In my experience, I don't believe I've seen MC use Bluetooth. With wifi turned off on the devices, and Bluetooth turned on, no connection is established. With wifi on and Bluetooth off, MC works and I presume either infrastructure wifi (if available) or peer-to-peer wifi are used. I'm trying to overcome two issues: Over time (since iOS 9.x), the radio transmit strength for MC over peer-to-peer wifi has decreased to the point that range is unacceptable for our use case. We need at least 150 feet range. We would like to extend this support to watchOS and the MC framework is not available. Regarding #1, I'd like to confirm that if infrastructure wifi is available, MC uses it. If infrastructure wifi is not available, MC uses peer-to-peer wifi. If this is true, then we can assure our customers that if infrastructure wifi is available at the venue, then with all devices connected to it, range will be adequate. If infrastructure wifi is not available at the venue, perhaps a mobile wifi router (battery operated) could be set up, devices connected to it, then range would be adequate. We are about to test this. Reasonable? Can we be assured that if infrastructure wifi is available, MC uses it? Regarding #2, given we are targeting minimum watchOS 7.0, would the available networking APIs and frameworks be adequate to implement our own equivalent of the MC framework so our app on iOS/iPadOS and watchOS devices could communicate? How much work? Where would I start? I'm new to implementing networking but experienced in using the MC framework. I'm assuming that I would write the networking code to use infrastructure wifi to achieve acceptable range. Many thanks! Tim

I’m working on an iOS parental-control app that needs to block specific network traffic (e.g. certain domains or URLs). We’ve already obtained the Family Controls entitlement (since our app is explicitly a parental-control solution), but we do not use MDM to supervise devices. In testing, our NEFilterDataProvider extension only activates when the device is enrolled under a managed Family Controls profile. I am aware that we can use a PacketTunnel to achieve this but i was wondering if there is any simpler solution to this? Thanks for you time!

Hi all. Title says it all really. I have an app on MacOS that sends multicast UDP to multiple iOS devices. It shows realtime bar numbers of music played back by a playback software. It was all working until I tried a direct ethernet connection between Mac and phone - a scenario that would be quite common in the theatre world where machines dont have internet connection and people dont rely on wifi. How can I choose which interface my app sends the data through? Here is my connection function: func openConnection() { let params = NWParameters.udp params.allowLocalEndpointReuse = true params.includePeerToPeer = true let endpoint = NWEndpoint.hostPort(host: host, port: port) let conn = NWConnection(to: endpoint, using: params) self.connection = conn conn.stateUpdateHandler = { state in switch state { case .ready: print("Multicast connection ready to \(self.host)") UDPClient.console.log("Multicast connection ready to \(self.host)") case .failed(let error): print("Multicast connection failed: \(error)") default: break } } let udpQueue = DispatchQueue(label: "UDPClientQueue") conn.start(queue: udpQueue) } Thanks for any help in advance!

Hi, we have an iOS application that runs a NEAppProxyProvider network extension. The configuration for the extension is delivered by MDM and we've noticed that some MDMs are beginning to force end users to select certificate based authentication as the auth type for the per-app VPN payload. This itself causes no problems, but when a certificate to use for the authentication is also provided in the profile, our extension fails to start. Our application does not use the credentials from the profile, certificate based or otherwise, so we aren't doing anything unusual with them either. We thought the problem might be caused because we lacked the com.apple.managed.vpn.shared entitlement that would be needed to access the certificate once it was on device (even though we never actually try to access it), but that did not fix the issue. We have also confirmed that this happens regardless of MDM used to configure the profile. Here are the relevant logs we are seeing that show the extension never starts: neagent: NEAgentSession: failed to create the delegate nesessionmanager:[313]: Tearing down XPC connection due to setup error: Error Domain=NEAgentErrorDomain Code=2 "(null)" : Last disconnect error for changed from "none" to "The VPN app used by the VPN configuration is not installed" STEPS TO REPRODUCE Create an application that establishes a basic per-app VPN (just a loopback works) using the network extension Using an MDM, create and deploy a per-app VPN profile with certificate based authentication (include a certificate as well) that uses the test application as a plugin. Using the MDM, assign another application to the per-app VPN. Try to connect to the internet using the assigned application, it should fail to connect because the system can't start the extension. For reference it appears that this issue is similar to ours: https://forums.developer.apple.com/forums/thread/746879 I've tried all the suggestions on that page, including adding a 'first-light' log and that is never seen. There are also no additional clues when adding the VPN debug profile to the device. Thanks!

Hi there, I'm trying to build a MacOS VPN application from scratch. My VPN application is slightly from normal ones, It will include an authentication token and underlying process information (pid, application path etc.) in each connection made to the VPN gateway. Consider it a poor man's zerotrust implementation. NetworkExtension and PacketTunnel is a must, thus to retrieve process information via audit tokens. However, I'm unable to find any working examples that can be built on MacOS 15.X. I tried to open an TSI case but didn't receive anything useful. Anyone?

Hello everyone, I’m currently working on a Swift project using the Network framework to create a multicast-based communication system. Specifically, I’m implementing both a multicast receiver and a sender that join the same multicast group for communication. However, I’ve run into some challenges with the connection management, replying to multicast messages, and handling state updates for both connections and connection groups. Below is a breakdown of my setup and the specific issues I’ve encountered. I have two main parts in the implementation: the multicast receiver and the multicast sender. The goal is for the receiver to join the multicast group, receive messages from the sender, and send a reply back to the sender using a direct connection. Multicast Receiver Code: import Network import Foundation func setupMulticastGroup() -> NWConnectionGroup? { let multicastEndpoint1 = NWEndpoint.hostPort(host: NWEndpoint.Host("224.0.0.1"), port: NWEndpoint.Port(rawValue: 45000)!) let multicastParameters = NWParameters.udp multicastParameters.multipathServiceType = .aggregate do { let multicastGroup = try NWMulticastGroup(for: [multicastEndpoint1], from: nil, disableUnicast: false) let multicastConnections = NWConnectionGroup(with: multicastGroup, using: multicastParameters) multicastConnections.stateUpdateHandler = InternalConnectionStateUpdateHandler multicastConnections.setReceiveHandler(maximumMessageSize: 16384, rejectOversizedMessages: false, handler: receiveHandler) multicastConnections.newConnectionHandler = newConnectionHandler multicastConnections.start(queue: .global()) return multicastConnections } catch { return nil } } func receiveHandler(message: NWConnectionGroup.Message, content: Data?, isComplete: Bool) { print("Received message from \(String(describing: message.remoteEndpoint))") if let content = content, let messageString = String(data: content, encoding: .utf8) { print("Received Message: \(messageString)") } let remoteEndpoint = message.remoteEndpoint message.reply(content: "Multicast group on 144 machine ACK from recv handler".data(using: .utf8)) if let connection = multicastConnections?.extract(connectionTo: remoteEndpoint) { connection.stateUpdateHandler = InternalConnectionRecvStateUpdateHandler connection.start(queue: .global()) connection.send(content: "Multicast group on 144 machine ACK from recv handler".data(using: .utf8), completion: NWConnection.SendCompletion.contentProcessed({ error in print("Error code: \(error?.errorCode ?? 0)") print("Ack sent to \(connection.endpoint)") })) } } func newConnectionHandler(connection: NWConnection) { connection.start(queue: .global()) connection.send(content: "Multicast group on 144 machine ACK".data(using: .utf8), completion: NWConnection.SendCompletion.contentProcessed({ error in print("Error code: \(error?.errorCode ?? 0)") print("Ack sent to \(connection.endpoint)") })) } func InternalConnectionRecvStateUpdateHandler(_ pState: NWConnection.State) { switch pState { case .setup: NSLog("The connection has been initialized but not started") case .preparing: NSLog("The connection is preparing") case .waiting(let error): NSLog("The connection is waiting for a network path change. Error: \(error)") case .ready: NSLog("The connection is established and ready to send and receive data.") case .failed(let error): NSLog("The connection has disconnected or encountered an error. Error: \(error)") case .cancelled: NSLog("The connection has been canceled.") default: NSLog("Unknown NWConnection.State.") } } func InternalConnectionStateUpdateHandler(_ pState: NWConnectionGroup.State) { switch pState { case .setup: NSLog("The connection has been initialized but not started") case .waiting(let error): NSLog("The connection is waiting for a network path change. Error: \(error)") case .ready: NSLog("The connection is established and ready to send and receive data.") case .failed(let error): NSLog("The connection has disconnected or encountered an error. Error: \(error)") case .cancelled: NSLog("The connection has been canceled.") default: NSLog("Unknown NWConnection.State.") } } let multicastConnections = setupMulticastGroup() RunLoop.main.run() Multicast Sender Code: import Foundation import Network func setupConnection() -> NWConnection { let params = NWParameters.udp params.allowLocalEndpointReuse = true return NWConnection(to: NWEndpoint.hostPort(host: NWEndpoint.Host("224.0.0.1"), port: NWEndpoint.Port(rawValue: 45000)!), using: params) } func sendData(using connection: NWConnection, data: Data) { connection.send(content: data, completion: .contentProcessed { nwError in if let error = nwError { print("Failed to send message with error: \(error)") } else { print("Message sent successfully") } }) } func setupReceiveHandler(for connection: NWConnection) { connection.receive(minimumIncompleteLength: 1, maximumLength: 65000) { content, contentContext, isComplete, error in print("Received data:") print(content as Any) print(contentContext as Any) print(error as Any) setupReceiveHandler(for: connection) } } let connectionSender = setupConnection() connectionSender.stateUpdateHandler = internalConnectionStateUpdateHandler connectionSender.start(queue: .global()) let sendingData = "Hello, this is a multicast message from the process on mac machine 144".data(using: .utf8)! sendData(using: connectionSender, data: sendingData) setupReceiveHandler(for: connectionSender) RunLoop.main.run() Issues Encountered: Error Code 0 Even When Connection Refused: On the receiver side, I encountered this log: nw_socket_get_input_frames [C1.1.1:1] recvmsg(fd 8, 9216 bytes) [61: Connection refused] Error code: 0 Ack sent to 10.20.16.144:62707 Questions: how do I reply to the message if above usage pattern is wrong? how do I get a NWConnection from the received message to create a separate connection for communication with the sender. Any insights or suggestions on resolving these issues or improving my multicast communication setup would be greatly appreciated. Thanks :)

Please consider this trivial C code which deals with BSD sockets. This will illustrate an issue with sendto() which seems to be impacted by the recent "Local Network" restrictions on 15.3.1 macos. #include <stdio.h> #include <stdlib.h> #include <netinet/in.h> #include <arpa/inet.h> #include "sys/socket.h" #include <string.h> #include <unistd.h> #include <ifaddrs.h> #include <net/if.h> // prints out the sockaddr_in6 void print_addr(const char *msg_prefix, struct sockaddr_in6 sa6) { char addr_text[INET6_ADDRSTRLEN] = {0}; printf("%s%s:%d, addr family=%u\n", msg_prefix, inet_ntop(AF_INET6, &sa6.sin6_addr, (char *) &addr_text, INET6_ADDRSTRLEN), sa6.sin6_port, sa6.sin6_family); } // creates a datagram socket int create_dgram_socket() { const int fd = socket(AF_INET6, SOCK_DGRAM, 0); if (fd < 0) { perror("Socket creation failed"); return -1; } return fd; } // returns a string representing the current local time char *current_time() { time_t seconds_since_epoch; time(&seconds_since_epoch); char *res = ctime(&seconds_since_epoch); const size_t len = strlen(res); // strip off the newline character that's at the end of the ctime() output res[len - 1] = '\0'; return res; } // Creates a datagram socket and then sends a messages (through sendto()) to a valid // multicast address. This it does two times, to the exact same destination address from // the exact same socket. // // Between the first and the second attempt to sendto(), there is // a sleep of 1 second. // // The first time, the sendto() succeeds and claims to have sent the expected number of bytes. // However system logs (generated through "log collect") seem to indicate that the message isn't // actually sent (there's a "cfil_service_inject_queue:4466 CFIL: sosend() failed 65" in the logs). // // The second time the sendto() returns a EHOSTUNREACH ("No route to host") error. // // If the sleep between these two sendto() attempts is removed then both the attempts "succeed". // However, the system logs still suggest that the message isn't actually sent. int main() { printf("current process id:%ld parent process id: %ld\n", (long) getpid(), (long) getppid()); // valid multicast address as specified in // https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml const char *ip6_addr_str = "ff01::1"; struct in6_addr ip6_addr; int rv = inet_pton(AF_INET6, ip6_addr_str, &ip6_addr); if (rv != 1) { fprintf(stderr, "failed to parse ipv6 addr %s\n", ip6_addr_str); exit(EXIT_FAILURE); } // create a AF_INET6 SOCK_DGRAM socket const int sock_fd = create_dgram_socket(); if (sock_fd < 0) { exit(EXIT_FAILURE); } printf("created a socket, descriptor=%d\n", sock_fd); const int dest_port = 12345; // arbitrary port struct sockaddr_in6 dest_sock_addr; memset((char *) &dest_sock_addr, 0, sizeof(struct sockaddr_in6)); dest_sock_addr.sin6_addr = ip6_addr; // the target multicast address dest_sock_addr.sin6_port = htons(dest_port); dest_sock_addr.sin6_family = AF_INET6; print_addr("test will attempt to sendto() to destination host:port -> ", dest_sock_addr); const char *msg = "hello"; const size_t msg_len = strlen(msg) + 1; for (int i = 1; i <= 2; i++) { if (i != 1) { // if not the first attempt, then sleep a while before attempting to sendto() again int num_sleep_seconds = 1; printf("sleeping for %d second(s) before calling sendto()\n", num_sleep_seconds); sleep(num_sleep_seconds); } printf("%s attempt %d to sendto() %lu bytes\n", current_time(), i, msg_len); const size_t num_sent = sendto(sock_fd, msg, msg_len, 0, (struct sockaddr *) &dest_sock_addr, sizeof(dest_sock_addr)); if (num_sent == -1) { fprintf(stderr, "%s ", current_time()); perror("sendto() failed"); close(sock_fd); exit(EXIT_FAILURE); } printf("%s attempt %d of sendto() succeeded, sent %lu bytes\n", current_time(), i, num_sent); } return 0; } What this program does is, it uses the sendto() system call to send a message over a datagram socket to a (valid) multicast address. It does this twice, from the same socket to the same target address. There is a sleep() of 1 second between these two sendto() attempts. Copy that code into noroutetohost.c and compile: clang noroutetohost.c Then run: ./a.out This generates the following output: current process id:58597 parent process id: 21614 created a socket, descriptor=3 test will attempt to sendto() to destination host:port ->ff01::1:14640, addr family=30 Fri Mar 14 20:34:09 2025 attempt 1 to sendto() 6 bytes Fri Mar 14 20:34:09 2025 attempt 1 of sendto() succeeded, sent 6 bytes sleeping for 1 second(s) before calling sendto() Fri Mar 14 20:34:10 2025 attempt 2 to sendto() 6 bytes Fri Mar 14 20:34:10 2025 sendto() failed: No route to host Notice how the first call to sendto() "succeeds", even the return value (that represents the number of bytes sent) matches the number of bytes that were supposed to be sent. Then notice how the second attempt fails with a EHOSTUNREACH ("No route to host") error. Looking through the system logs, it appears that the first attempt itself has failed: 2025-03-14 20:34:09.474797 default kernel cfil_hash_entry_log:6082 <CFIL: Error: sosend_reinject() failed>: [58597 a.out] <UDP(17) out so 891be95f3a70c605 22558774573152560 22558774573152560 age 0> lport 0 fport 12345 laddr :: faddr ff01::1 hash 1003930 2025-03-14 20:34:09.474806 default kernel cfil_service_inject_queue:4466 CFIL: sosend() failed 65 (notice the time on that log messages, they match the first attempt from the program's output log) So even though the first attempt failed, it never got reported back to the application. Then after sleeping for (an arbitrary amount of) 1 second, the second call fails with the EHOSTUNREACH. The system logs don't show any error (at least not the one similar to that previous one) for the second call. If I remove that sleep() between those two attempts, then both the sendto() calls "succeed" (and return the expected value for the number of bytes sent). However, the system logs show that the first call (and very likely even the second) has failed with the exact same log message from the kernel like before. If I'm not wrong then this appears to be some kind of a bug in the "local network" restrictions. Should this be reported? I can share the captured logs but I would prefer to do it privately for this one. Another interesting thing in all this is that there's absolutely no notification to the end user (I ran this program from the Terminal) about any of the "Local Network" restrictions.