Networking

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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

Networking Documentation

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certificate validation in SwiftUI App fails
I'm writing an LDAP Browser app using SwiftUI. I tested my LDAP code using a command line app that uses the exact same libraries and it successfully connects to my LDAP server over a TLS connection. I did need to install the CA cert into the system keychain. The SwiftUI version, using the exact same code and parameters returns an "Unknown CA" error. It works fine without TLS. Can anyone explain why certificate validation is different for a GUI app?
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275
Feb ’25
DNS Resolution fails in 15.4
Hi, DNS resolution using libresolv (res_nquery) fails in 15.4 when connected to VPN. The same is working fine for 15.3 and lower and this happens for all the domains. The method returns -1 and res->res_h_errno is set to 2. In wireshark we can see that the DNS request is sent and server also returns the response successfully. The same works fine if we use TCP instead of UDP by setting the following option res->options |= RES_USEVC;
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188
Apr ’25
Running headless app as root for handling VPN and launching microservices
Hello to all I have coded in swift a headless app, that launches 3 go microservices and itself. The app listens via unix domain sockets for commands from the microservices and executes different VPN related operations, using the NEVPNManager extension. Because there are certificates and VPN operations, the headless app and two Go microservices must run as root. The app and microservices run perfectly when I run in Xcode launching the swift app as root. However, I have been trying for some weeks already to modify the application so at startup it requests the password and runs as root or something similar, so all forked apps also run as root. I have not succeeded. I have tried many things, the last one was using SMApp but as the swift app is a headless app and not a CLI command app it can not be embedded. And CLI apps can not get the VPN entitlements. Can anybody please give me some pointers how can I launch the app so it requests the password and runs as root in background or what is the ideal framework here? thank you again.
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Structured Concurrency with Network Framework Sample
I am trying to migrate an app to use Network framework for p2p connection. I came across this great article for migrating to Network framework however this doesnt use the new structured concurrency. This being introduced with iOS 26, there doesnt seem to be any sample code available on how to use the new classes. I am particularly interested in code samples showing how to add TLS with PSK encryption support and handling of switching between Wifi and peer to peer interface with the new structured concurrency supported classes. Are there any good resources I can refer on this other than the WWDC video?
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URL Session randomly returns requests extremely slowly!
Hi, I'm experiencing intermittent delays with URLSession where requests take 3-4 seconds to be sent, even though the actual server processing is fast. This happens randomly, maybe 10-20% of requests. The pattern I've noticed is I create my request I send off my request using try await urlSession.data(for: request) My middleware ends up receiving this request 4-7s after its been fired from the client-side The round trip ends up taking 4-7s! This hasn't been reproducible consistently at all on my end. I've also tried ephemeral URLSessions (so recreating the session instead of using .shared so no dead connections, but this doesn't seem to help at all) Completely lost on what to do. Please help!
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IOS App tcp connect and local network permission
Recently, my application was having trouble connecting socket using TCP protocol after it was reinstalled. The cause of the problem was initially that I did not grant local network permissions when I reinstalled, I was aware of the problem, so socket connect interface worked fine after I granted permissions. However, the next time I repeat the previous operation, I also do not grant local network permissions, and then turn it back on in the Settings, and socket connect interfcae does not work properly (connect interface return errno 65, the system version and code have not changed). Fortunately, socket connect success after rebooting the phone, and more importantly, I was able to repeat the problem many times. So I want to know if the process between when I re-uninstall the app and deny local network permissions, and when I turn it back on in Settings, is that permissions have been granted normally, and not fake, and not required a reboot to reset something for socket coonnect to take effect.
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244
Jun ’25
WebAuthenticationSession under a carrier-provided satellite network?
(related post: How to optimize my app for for a carrier-provided satellite network? ) I am trying to implement an app so that it works under a carrier-provided satellite network. The app uses (AS)WebAuthenticationSession for signing in. If the app is entitled to access a satellite network, will (AS)WebAuthenticationSession work as well? How about WKWebView and SFSafariViewController? Is there a way to test(simulate) a ultra-constrained network on a device or a simulator to see the expected behavior? Thanks,
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380
Jul ’25
Change includeAllNetworks from NetworkExtension while tunnel is running
Hi, I saw that almost each OS version, on ios and macos, handles differently changing includeAllNetworks while the tunnel is running. On some the entire OS reports no-net, while others, specially latest versions, handle this fine. Can includeAllNetworks be changed while the tunnel is running, or the tunnel must be stopped and restarted with the new value? e.g. the tunnel is started with it set to false, but later is changed to true into VPN profile. And on the same note, regarding setTunnelNetworkSettings, can this be called multiple times while the tunnel is running? For example if the VPN server IP changes. Because what I've saw each call to setTunnelNetworkSettings after VPN connected results in at least DNS leaks, because the routing table is recreated. Let me know if it is easier to track to create separate questions. Thanks
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1k
Mar ’25
XPC listener initialized in System Extesnion invalidates incoming connection under certain conditions
I found a problem where a process tries to connect to System Extension and connection is invalidated. XPC listener has to be disposed and initialized again. This happens when System Extension executes tasks in following order: NSXPCListener initialized NSXPCListener.resume() NSProvider.startSystemExtensionMode() Result: Connection is invalidated and not only that the client has to retry connection, nut also System Extension must reinitialize listener (execute step 1 and 2). However if I call NSProvider.startSystemExtensionMode() NSXPCListener initialized NSXPCListener.resume() It works as expected and even if the connection is invalidated/interrupted, client process can always reconnect and no other action is necessary in System Extension (no need to reinitialize XPC listener), In Apple docs about NSProvider.startSystemExtensionMode() it says that this method starts handling request, but in another online article written by Scott Knight I found that startSystemExtensionMode() also starts listener server. Is that right? PLease could you add this info into the docs if it is so? https://knight.sc/reverse%20engineering/2019/08/24/system-extension-internals.html I would like to use following logic: Call NSProvider.startSystemExtensionMode() only under certain circumstances - I have received some configuration that I need to process and do some setup. If I don't receive it, there is no reason to call startSystemExtensionMode() yet, I don't need to handle handleNewFlow() yet. Connect XPC client to System Extension under certain conditions. Ideally communicate with client even though System Extension is not handling network requests yet, that is without receiving handleNewFlow(). Basically I consider XPC and System Extension handling network requests as separate things. Is that correct, are they separate and independent? Does XPC communication really depend on calling startSystemExtensionMode()? Another potential issue: Is it possible that XPC listener fails to validate connection when client tries to connect before System Extension manages to complete init and park the main thread in CFRunLoop? Note: These querstions arose mostly from handling upgrades of System Extension (extension is already running, network filter is created and is connected and new version of the app upgrades System Exension). Thanks.
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Apr ’25
iPhone 17(iOS26) Unable to join the Wi-Fi(TKIP)
Device: iPhone 17 Series System: iOS 26.0.0 Wi-Fi: TKIP encryption protocol Question: Unable to join the network We have several products that are used by connecting to iPhone via Wi-Fi. Recently, many customers who have purchased the iPhone 17 series have reported that they are unable to connect to Wi-Fi. For Wi-Fi with TKIP encryption, after entering the password correctly to connect to the Wi-Fi, a pop-up appears stating "Unable to join the network.". Only Wi-Fi with WPA2-AES can be used normally. Before that, during the iPhone 11 era or even earlier, the TKIP encryption method was in normal use. However, the new iPhone models were incompatible with it, which obviously caused great inconvenience. I hope the engineers can fix this issue to support Wi-Fi with older encryption protocols.
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Replacing Packet Filter (pf) with Content Filter for VPN Firewall Use Case
Hi, We're in the process of following Apple’s guidance on transitioning away from Packet Filter (pf) and migrating to a Network Extension-based solution that functions as a firewall. During this transition, we've encountered several limitations with the current Content Filter API and wanted to share our findings. Our VPN client relies on firewall functionality to enforce strict adherence to split tunneling rules defined via the routing table. This ensures that no traffic leaks outside the VPN tunnel, which is critical for our users for a variety of reasons. To enforce this, our product currently uses interface-scoped rules to block all non-VPN traffic outside the tunnel. Replicating this behavior with the Content Filter API (NEFilterDataProvider) appears to be infeasible today. The key limitation we've encountered is that the current Content Filter API does not expose information about the network interface associated with a flow. As a workaround, we considered using the flow’s local endpoint IP to infer the interface, but this data is not available until after returning a verdict to peek into the flow’s data—at which point the connection has already been established. This can result in connection metadata leaking outside the tunnel, which may contain sensitive information depending on the connection. What is the recommended approach for this use case? NEFilterPacketProvider? This may work, but it has a negative impact on network performance. Using a Packet Tunnel Provider and purely relying on enforceRoutes? Would this indeed ensure that no traffic can leak by targeting a specific interface or by using a second VPN extension? And more broadly—especially if no such approach is currently feasible with the existing APIs—we're interpreting TN3165 as a signal that pf should be considered deprecated and may not be available in the next major macOS release. Is that a reasonable interpretation?
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May ’25
DNSServiceBrowse() callback receives error code -65570
Hi, I am trying to update an old prototype I made for tvOS using DNSServiceBrowse(). The target was tvOS 17. My old build from September 2023 still works fine: It can discover computers on the same local network as the Apple TV (simulator). However, now that I am using Xcode 16, the DNSServiceBrowse() callback (of type DNSServiceBrowseReply) receives the error code: -65570. The call to DNSServiceBrowse() itself returns no error, neither does the following call to DNSServiceProcessResult() — which actually triggers the call of the callback. I found nowhere in the Internet any list of possible error codes received by the callback, so I have no idea what it means. So, my first question is: What does this error code mean? (And is there any list of the possible errors somewehere, with their meaning?) Since it was a prototype, I have no provisioning profile defined for it. Could that be related to the issue? Since I will make a real app out that prototype (targeting tvOS 18), I will have to define a provisioning profile for it. Would a provisioning profile for the app solve the issue? If yes, are there any requirements for that profile that I should take into account to solve the issue? Thank you in advance for any help, Marc
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Jun ’25
System Network Extension and Sleep
I've implemented a custom VPN for macOS (system extension, Packet Tunnel Provider, Developer ID). My tunneling logic uses BSD sockets. My VPN is configured with on-demand and should always connect when there's traffic: targetManager?.isOnDemandEnabled = true targetManager?.onDemandRules = [NEOnDemandRuleConnect()] I have encountered some issues when the device enters sleep (or waking up from sleep). I've tried two scenarios. Scenario 1: protocolConfiguration?.disconnectOnSleep = true With this flag set, the OS will disconnect the VPN just before entering to sleep. However, there were cases when the OS disconnected the VPN but immediately restarted it - probably because of how I defined the on-demand rules. This resulted in the VPN disconnection, then trying to reconnect, and then the Mac entered sleep. When the Mac woke up, the VPN didn't work well. Is there a way to avoid waking up, just before the Mac enters sleep? Scenario 2: protocolConfiguration?.disconnectOnSleep = false Disconnect on sleep is unset, and I've implemented the sleep/wake functions at the provider. With this configuration, the OS won't disconnect the VPN, so even in sleep, the extension should stay 'alive,' so it won't have the problem from (1). But in this case, I had other problems: On sleep, I'm disconnecting the tunnel. But sometimes, on wake(), all my network calls fail. Are the interfaces still down? How can I detect this case from the system extension? Is it possible that the OS would call sleep and then quickly call wake? Is it possible that after sleep, the OS would call the startTunnelWithOptions() function? Is it possible to restart the extension from a clean state right from the wake() function?
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779
Jan ’25
Hide OS logs coming out of the Network framework (category: com.apple.network)
I'm establishing a connection with NWListener and NWConnection which is working great. However, if the listener disappears, a lot of logs are appearing: Is there a way to hide these logs? I'm aware of OS_ACTIVITY_MODE=disabled, but that will also hide a lot of other logs. I also know you can hide these using Xcode's filtering. I'm looking for a programmatically way to hide these completely. I'm not interested in seeing these at all, or, at least, I want to be in control. Thanks!
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Apr ’25
How to configure macOS app permission MANUALLY (not GUI)
I need to run multiple, slightly different copies of a modeling tool, which all need access to a model repository on a different machine. Security Settings -> Network tends to pick one modeling tool (and unfortunately the wrong one) for permission, but the dialog offers no way to add the other copies manually. Where can I configure the permission on low level. [macOS Sequoia 15.6.1]
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Sep ’25
A simple CLI DNS-SD browser...
I am learning how to use DNS-SD from swift and have created a basic CLI app, however I am not getting callback results. I can get results from cli. Something I am doing wrong here? dns-sd -G v6 adet.local 10:06:08.423 Add 40000002 22 adet.local. FE80:0000... dns-sd -B _adt._udp. 11:19:10.696 Add 2 22 local. _adt._udp. adet import Foundation import dnssd var reference: DNSServiceRef? func dnsServiceGetAddrInfoReply(ref: DNSServiceRef?, flags: DNSServiceFlags, interfaceIndex: UInt32, errorCode: DNSServiceErrorType, hostname: UnsafePointer<CChar>?, address: UnsafePointer<sockaddr>?, ttl: UInt32, context: UnsafeMutableRawPointer?) { print("GetAddr'd") print(hostname.debugDescription.utf8CString) print(address.debugDescription.utf8CString) } var error = DNSServiceGetAddrInfo(&reference, 0, 0, DNSServiceProtocol(kDNSServiceProtocol_IPv6), "adet.local", dnsServiceGetAddrInfoReply, nil) print("GetAddr: \(error)") func dnsServiceBrowseReply(ref: DNSServiceRef?, flags: DNSServiceFlags, interfaceIndex: UInt32, errorCode: DNSServiceErrorType, serviceName: UnsafePointer<CChar>?, regType: UnsafePointer<CChar>?, replyDomain: UnsafePointer<CChar>?, context: UnsafeMutableRawPointer?) { print("Browsed") print(serviceName.debugDescription.utf8CString) print(replyDomain.debugDescription.utf8CString) } error = DNSServiceBrowse(&reference, 0, 0, "_adt._udp", nil, dnsServiceBrowseReply, nil) print("Browse: \(error)") Foundation.RunLoop.main.run() Info.plist <?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>NSLocalNetworkUsageDescription</key> <string>By the Hammer of Grabthor</string> <key>NSBonjourServices</key> <array> <string>_adt._udp.</string> <string>_http._tcp.</string> <string>_http._tcp</string> <string>_adt._udp</string> </array> </dict> </plist>
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Jun ’25
Allow "Browser" to find devices on local networks
Hi, I am developing the browser based on Chromium, which initially relies on the nw_browser stack for discovering locally available network resources. We have observed an issue where, after each software update—specifically, whenever additional files are written into the application bundle—a popup appears requesting the user to allow local network access, even if this permission was already granted. The behavior is reproducible: simply overwriting files in the app bundle (we are using rsync as Chromium), even while the application is already running, causes the prompt to reappear. We have also noticed that Chromium itself exhibits the same behavior. Also I found the mess in system settings, it has several Google Chrome for example: https://www.loom.com/share/da401f39ab134628807d77f1ca3185f5?from_recorder=1&focus_title=1 We would like to provide a smoother experience for our users and avoid confusing them with repeated permission prompts. Could you please advise on possible approaches or best practices to improve our update mechanism in this regard?
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249
Sep ’25
Changes to Personal Hotspot in iOS 18.0
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.
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Jan ’25
Split tunnel w/o changing route table
I've built a VPN app that is based on wireguard on macOS (I have both AppStore ver. and Developer ID ver). I want to achieve split tunneling function without changing the system route table. Currently, I'm making changes in PacketTunnelProvider: NEPacketTunnelProvider. It has included/excluded routes that function as a split tunnel, just that all changes are immediately reflected on the route table: if I run netstat -rn in terminal, I would see all rules/CIDRs I added, displayed all at once. Since I have a CIDR list of ~800 entries, I'd like to avoid changing the route table directly. I've asked ChatGPT, Claude, DeepSeek, .etc. An idea was to implement an 'interceptor' to intercept all packets in packetFlow(_:readPacketsWithCompletionHandler:), extract the destination IP from each packet, check if it matches your CIDR list, and either reinject it back to the system interface (for local routing) or process it through your tunnel. Well, LLMs could have hallucinations and I've pretty new to macOS programming. I'm asking to make sure I'm on the right track, not going delusional with those LLMs :) So the question is, does the above method sounds feasible? If not, is it possible to achieve split tunneling without changing the route table?
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120
Jun ’25