General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Wi-Fi (general): How to modernize your captive network developer news post Wi-Fi Fundamentals forums post Filing a Wi-Fi Bug Report forums post Working with a Wi-Fi Accessory forums post — This is part of the Extra-ordinary Networking series. Wi-Fi (iOS): TN3111 iOS Wi-Fi API overview technote Wi-Fi Aware framework documentation WirelessInsights framework documentation iOS Network Signal Strength forums post Network Extension Resources Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

Many times the device totally lost connectivity, WIFI is completely down, no ip was assigned after device wakeup. From system log I can see BPF socket for DHCP was closed and detached right after attached to en0 in DHCP INIT phase, as result even the DHCP server sent back OFFER(I see server sent OFFER back from packet capture), but there is no persistent BPF socket since it is closed reception during the entire INIT phase. It is definitely an OS issue, is it a known issue? Please help understand Why BPF socket was close right after sending DISCOVER? Default 0x0 0 0 kernel: bpf26 attached to en0 by configd:331 2026-03-25 14:06:33.625851+0100 0x31dea Default 0x0 0 0 kernel: bpf26 closed and detached from en0 fcount 0 dcount 0 by configd:331 System log and packet capture attach, please check.

We are seeing an issue after updating iPads to iPadOS 26.4 where cellular service is lost until network settings are reset. Environment: Devices managed via Apple Business Manager and Microsoft Intune Carrier: Verizon Confirmed affected devices: iPad (9th generation) eSIM Behavior: After update, device shows no cellular service No prompt to re-activate or re-add the cellular plan The plan appears to still be present on the device Workaround observed: Resetting Network Settings restores service Notes: This does not appear to be a provisioning issue (no need to re-add eSIM) Behavior suggests the cellular/eSIM state may not be initializing correctly after update Toggling Cellular or Airplane mode has not yet been tested for service restoration. We have not yet confirmed whether devices using a physical SIM are affected Still gathering data on scope across additional iPad models Additional observation: We have not observed this behavior on iPhones (e.g., iPhone 16 on iOS 26.4 with LTE remains unaffected) Has anyone else observed similar behavior on iPadOS 26.4, particularly on managed devices or eSIM configurations?

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?

Hello All, I have a app which has a WKWebview loading some code from a remote origin - https://my-company.example.com When WKWebview loads remote origin, that page does load some of the sub-resources from in-app localhost server (GCDWebserver), i.e. reach out to a loopback based in-app GCDWebserver, now to provide a secure context I had an existing setup with self signed cert, CORS and everything needed for https on localhost. And the sub-resources used to load fine from https localhost till 26.4 Starting with iOS 26.4 it started breaking with TLSv1_ALERT_UNKNOWN_CA Is there any known guidance for this? Technically as per w3c spec, localhost is considered secure context by default right? and no special things need to be done. But ios/Webkit seem to be different in this regard. Is this a known issue, and is there any mitigation here? I'll try to provide a sample app soon if possible.

After implementing the new structured concurrency API's for Network framework, we are noticing a few memory leaks in the Network framework when using API's like onViabilityUpdate and onBetterPathUpdate. Whenever a previously established connection is disconnected, the NWConnection object is never released by the Network framework when we use the 2 API's mentioned. Irrespective of what goes inside these handlers(or leave it empty), the connection object is leaking. If I comment out the handlers, there is no memory leak. Posting this here in the forum to understand if others have encountered similar issues and found a workaround? Raised a feedback assistant request with all the details and a sample app here: FB22339653

I’m working on a product that includes TLS inspection capability. TLS inspection using a local MitM requires installing a trusted root certificate which is then used to create masquerade certificates to intercept and forward TLS traffic through the proxy. For manual installation the end user is required to authenticate as an administrator to modify the trust settings on our internal CA’s root certificate. My question concerns the options for enterprise deployment using an MDM. We want the generated root certificate to be unique to each endpoint so that if a private key is compromised it can’t be used to intercept traffic anywhere else. We can install a “certificate trust” configuration profile from the MDM but this requires a base64 encoded string of the root certificate. In effect the MDM needs to obtain the certificate from the endpoint and then send it back in the form of a configuration profile. I’m not aware that MDMs like Jamf can be configured to do this directly so we’re looking for any other mechanism to have macOS trust a locally generated certificate via MDM based on some non endpoint-unique criteria? One option might be to use an external CA with a trusted certificate to sign an intermediate endpoint certificate but this creates a significant risk if the external trusted certificate were ever compromised. Is this a common industry practice? So my question remains is there a better way to trust our per endpoint root certificate via MDM without needing to install a unique per endpoint configuration profile?

Hello, I have an app that is using iOS 26 Network Framework APIs. It is using QUIC, TLS 1.3 and Bonjour. For TLS I am using a PKCS#12 identity. All works well and as expected if the devices (iPhone with no cellular, iPhone with cellular, and iPad no cellular) are all on the same wifi network. If I turn off my router (ie no more wifi network) and leave on the wifi toggle on the iOS devices - only the non cellular iPhone and iPad are able to discovery and connect to each other. My iPhone with cellular is not able to. By sharing my logs with Cursor AI it was determined that the connection between the two problematic peers (iPad with no cellular and iPhone with cellular) never even makes it to the TLS step because I never see the logs where I print out the certs I compare. I tried doing "builder.requiredInterfaceType(.wifi)" but doing that blocked the two non cellular devices from working. I also tried "builder.prohibitedInterfaceTypes([.cellular])" but that also did not work. Is AWDL on it's way out? Should I focus my energy on Wi-Fi Aware? Regards, Captadoh

This is a bit complicated to explain so bare with me. I am working on building an app that allows you to send real time video/camera captures from one Apple device to another. I am using a custom UDP protocol built on top of NWListener, NWBrowser, and NWConnection APIs. It works fine, but there are a few issues that seems to all be related to awdl: When transmitting via WiFi over the router (not using peer-to-peer), there are periodic interruptions when the wireless card on the device changes channels for awdl polling. This is resolved by changing the 5GHz WiFi channel on the router to channel 149 (or disabling AWDL altogether which is not really feasible). In order to work around number 1, I decided to build in an option to toggle/prefer peer-to-peer transmission in the app thinking that if everything goes over a peer-to-peer connection the jitter caused from the channel switching should go away. This also works, but with an important caveat. The default transmission is extremely choppy until you take an OS action that “elevates” the AWDL connection into “realtime” mode. I am using includePeerToPeer on the listener, browser, and connection as well as serviceClass interactiveVideo. For number 1, you can understand that asking users to change the channel on their router is not a great user experience, but the problem is the peer-to-peer connection workaround is also not great by default. For number 2, as an example of the behavior, I can send a stream from my Mac to my iPad over a peer-to-peer connection and it works but the video is very choppy until I move my cursor from my Mac to my iPad to trigger Universal Control. I captured the OS logs while doing this and can confirm that something happens to trigger “realtime” mode on the AWDL connection. After that, the streaming is totally smooth with zero latency. Some log samples: 2026-03-19 12:42:01.277968-0400 0x1ae294c Default 0x0 495 3 rapportd: (CoreUtils) [com.apple.rapport:CLinkD] Update client from UniversalControl:697 2026-03-19 12:42:01.278031-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Connect start: 'CLink-ed3b9618b4e0._companion-link._tcp.local.%13' 2026-03-19 12:42:01.278149-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Querying SRV CLink-ed3b9618b4e0._companion-link._tcp.local.%13 2026-03-19 12:42:01.279454-0400 0x1ae253a Info 0x0 382 0 wifip2pd: [com.apple.awdl:datapathInitiator] Created AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52> 2026-03-19 12:42:01.279498-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Resolving DNS f970afcc-1f1c-47af-a3f3-0236c9f9bbb0.local.%13 2026-03-19 12:42:01.279588-0400 0x1ae253a Default 0x0 382 0 wifip2pd: [com.apple.awdl:datapathInitiator] AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52> was started 2026-03-19 12:42:01.282537-0400 0x1ae294c Default 0x0 495 0 rapportd: (Network) [com.apple.network:path] nw_path_evaluator_start [5C54D967-624D-4269-B080-6C7AE63218C7 IPv6#1e905043%awdl0.49154 generic, attribution: developer] path: satisfied (Path is satisfied), interface: awdl0[802.11], dns, uses wifi 2026-03-19 12:42:01.596450-0400 0x1ae253a Debug 0x0 382 0 wifip2pd: [com.apple.awdl:driver] Received event realtimeMode 2026-03-19 12:42:01.596589-0400 0x1ae253a Default 0x0 382 0 wifip2pd: [com.apple.awdl:interface] Realtime mode updated true I noticed that on iOS 26 and iPadOS 26 a realtime mode was added specifically to the Wi-Fi Aware API which I assume does what I want: https://developer.apple.com/documentation/wifiaware/waperformancemode/realtime, but I am looking for a solution that works with the existing network API and also on previous OS versions. I have already tried a lot of things, but is there any way to programmatically trigger “realtime” mode? For additional context, the goal here is to have extremely low latency that also works for gaming. The actual latency introduced in 1 is approximately 30-50ms around once a second… adding a buffer to the stream makes the video completely smooth, but the extra delay on the receiver end is not acceptable for this use case. Any help or ideas would be appreciated. I can’t easily share a reproduce case right now, and even if I could, getting multiple devices into the exact state along with the router configuration in order to reproduce is going to be pretty difficult anyway.

In macOS Tahoe 26.2 an RDMA capability was added for Thunderbolt-5 interfaces. This has been demonstrated to significantly decrease the latency and maintain bandwidth for "clustered" Apple Silicon devices with TB5. What is the ideal and the maximum RDMA burst width for transfers over RDMA-enabled Thunderbolt-5 interfaces?

I want to track down which part of an app contacts a given domain listed in its App Privacy Report. Following the instructions given here I am able to capture a packet trace, but traffic to the domain in question is encrypted using QUIC. Is there a way to insert e.g. mitmproxy into the capture process in order to get hold of the SSLKEYLOGFILE so that I can decrypt the traffic?

Hello and Good day! We are conducting Bonjour Conformance Test (BCT) for Printer device. BCT result is PASSED but with warning in Multicast DNS, specifically, WARNING: SHARED REPLY TIMING - UNIFORM RANDOM REPLY TIME DISTRIBUTION Other Shared Reply Timing is passed: PASSED: MULTIPLE QUESTIONS - SHARED REPLY TIMING - UNIFORM RANDOM REPLY TIME DISTRIBUTION Environment: BCT Tool Version: 1.5.4 (15400) MacOS Sequioa 15.5 DUT Firmware : Linux Debian 9 Apple mDNSResponder 1790.80.10 Service types: _ipps._tcp, _uscans._tcp, _ipp._tcp, _uscan._tcp Router : NEC AtermWR8370N Setup: 1-to-1 [Mac->Router<-DUT connection] Based on debug.log, this is where WARNING occurs: NOTICE 2026-03-04 10:51:06.870187+0900 _shared_reply_timing 04103: Shared reply response times: min = 26ms, max = 114ms, avg = 65.50ms WARNING 2026-03-04 10:51:06.870361+0900 _shared_reply_timing 04136: 50 percent of the replies within the correct range fell in the interval 20ms and 46ms (should be close to 25%). PASSED (SHARED REPLY TIMING) In the same debug.log for MULTIPLE QUESTIONS - SHARED REPLY TIMING is PASSED: NOTICE 2026-03-04 10:52:29.912334+0900 _shared_reply_timing 04103: Shared reply response times: min = 22ms, max = 112ms, avg = 78.00ms DEBUG_2 2026-03-04 10:52:29.912849+0900 recv_packet 01997: received packet (558 bytes) PASSED (MULTIPLE QUESTIONS - SHARED REPLY TIMING) [Details] Looking at Bonjour_Conformance_Guideline.pdf https://download.developer.apple.com/Documentation/Bonjour_Conformance_Test_Guideline/Bonjour_Conformance_Guideline.pdf there were some differences: In 1.6.2 Expected Result: Test Result File of Test that All Tests Passed, this is not displayed: PASSED: SHARED REPLY TIMING - UNIFORM RANDOM REPLY TIME DISTRIBUTION And in II.8 Shared Reply Timing: (Ideally, 25% of the answers should fall in each 21ms quadrant of the range 20ms - 125ms.) and comparing to the debug.log, there was a discrepancy of the interval, because 20ms and 46ms is 26ms interval. From RFC6762 6. Responding, Ideal range is from 20ms-120ms Because of this, please advise on the questions below: I would like to know on the possible cause and resolution for these WARNINGS. And since in current BCT result, (Test result integrity signature is generated), I would like to know if this is acceptable for BCT certification. Thank you.

Showing All Messages [!] Error installing FBSDKLoginKit [!] /usr/bin/curl -f -L -o /Volumes/workspace/tmp/d20260316-6574-ros9od/file.zip https://github.com/facebook/facebook-ios-sdk/releases/download/v18.0.2/FacebookSDK_Dynamic.xcframework.zip --create-dirs --netrc-optional --retry 2 -A 'CocoaPods/1.16.2 cocoapods-downloader/2.1' % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- 0:00:02 --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- 0:00:03 --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- 0:00:04 --:--:-- 0 0 0 0 0 0 0 0 0 --:--:-- 0:00:05 --:--:-- 0 curl: (35) Recv failure: Connection reset by peer Command exited with non-zero exit-code: 1 Running ci_post_clone.sh script failed (exited with code 1). Executable scripts are run using the interpreter specified in the shebang line.

On my iPhone 16 Pro and iPhone 16 Pro Max devices, running iOS 26.0, 26.0.1, and 26.1, Wi-Fi raw socket communication works flawlessly. Even after keeping the connection active for over 40 minutes, there are no disconnections during data transmission. However, on the iPhone 17 and iPhone 17 Pro, the raw socket connection drops within 20 seconds. Once it disconnects, the socket cannot reconnect unless the Wi-Fi module itself is reset. I believe this issue is caused by a bug in the iPhone 17 series’ communication module. I have looked into many cases, and it appears to be related to a bug in the N1 chipset. Are there any possible solutions or workarounds for this issue?

Hello, We are facing what we believe is a compatibility issue with two networking APIs. If the Network extension VPN configuration has includeAllNetworks flag enabled and the NEHotspotHelper is registered. The user has internet connection but it is blocked, and there user will get internet back only after restarting the device. VPN Configuration is as below while connecting to VPN, { localizedDescription = WLVPN WireGuard Configuration enabled = YES protocolConfiguration = { serverAddress = <18-char-str> passwordReference = {length = 20, bytes = 0x67656e70ed0d05c06b1b4896bf4fef2031e1a92d} disconnectOnSleep = NO includeAllNetworks = YES excludeLocalNetworks = YES excludeCellularServices = YES excludeAPNs = YES excludeDeviceCommunication = YES enforceRoutes = NO providerBundleIdentifier = com.wlvpn.ios.consumervpn.network-extension } onDemandEnabled = NO onDemandRules = () } After running the code shown below. Regardless if the VPN is connected or not, the user needs to restart his device to regain internet access. private let neHelperQueue = DispatchQueue(label: "com.wlvpn.ios.consumervpn.hotspot", attributes: DispatchQueue.Attributes.concurrent) let options: [String: NSObject] = [kNEHotspotHelperOptionDisplayName : "" as NSObject] let status = NEHotspotHelper.register(options: nil, queue: neHelperQueue) { cmd in NSLog("Received command: \(cmd.commandType.rawValue)") } We need to use the includeAllNetworks flag to prevent the novel "Tunnel vision" vulnerability. Can we please have some help getting confirmation if both functionalities are compatible or if there's a way to enable them at the same time?

Is it somehow possible to get the transport layer (UDP and TCP) payload amounts for TLS or QUIC connections established via the Network framework? (From within the app itself that establishes the connections.) I am currently using the ntstat.h kernel socket calls, but I hope there is a simpler solution. With ntstat, I have not yet been able to observe a specific connection. I have to search for the connection I am looking in all (userspace) connections.

Our watchOS app is exploring adding audio VOIP calling capability using our in-home platform. We are using LiveCommunicationKit for this and have that all hooked up nicely in a proof of concept implementation. Our use case is primarily based around supporting end-users through various tasks with assistance from a remotely based expert. We would like for our platform to be able to display visual content on the watch's screen during the call – in other words, we would like to be able to treat this as a video call. LiveCommunicationKit fully supports all video-related flags on watchOS and doesn't appear to have any different symbol availability versus its iOS version. This high-quality thread (https://developer.apple.com/forums/thread/798090) from a DTS engineer suggests that our use case should be valid (i.e. whiteboarding apps) and that the system's response to an accepted income video call is to dismiss the LCK's incoming call screen and bring the target app to the foreground, allowing it to render its custom content. Unfortunately, on watchOS the system doesn't seem to treat a video call any differently from an audio call, and won't dismiss the system UI once it's answered. We fully realize that Apple Watch doesn't have a camera for outbound video, doesn't support VideoToolbox or other low-level video convenience libraries for simplified rendering and decoding, etc. That's not what we're worried about (yet). The documentation is at best unclear about whether LCK (or CallKit, for that matter) can hand off calls flagged as video-compatible according to how we think they should, which is passing foreground UI over to the app once the call has been accepted by the user. Can any Apple people shed some light on this? I recognize we are probably trying to do something not many people have before.

I am using Network framework for connecting two iPad devices that are connected through LAN and has Wifi enabled. I have enabled peerToPeerIncluded. I would like to understand how the framework chooses the interface types for browsing and discovering devices. When I start a browser with browser.run or listener.run, does the browser and advertiser browse and listen on all available interface types? My concern is that if it does in only one interface, Is there a chance that the browser is browsing in one interface(Lets say WiredEthernet) and the listener is listening on another interface(Lets say AWDL) and they dont discover?

All of our uses of CFSockets have started causing crashes in iOS 16. They seem to be deprecated so we are trying to transition over to using the Network framework and NWConnection to try to fix the crashes. One of our uses of them is to ping a device on the local network to make sure it is there and online and provide a heartbeat status in logs as well as put the application into a disabled state if it is not available as it is critical to the functionality of the app. I know it is discouraged to disable any functionality based on the reachability of a resource but this is in an enterprise environment where the reachability of this device is mission critical. I've seen other people ask about the ability to ping with the Network framework and the answers I've found have said that this is not possible and pointed people to the SimplePing sample code but it turns out our existing ping code is already using this technique and it is crashing just like our other CFSocket usages, inside CFSocketInvalidate with the error BUG IN CLIENT OF LIBPLATFORM: Trying to recursively lock an os_unfair_lock. Is there any updated way to perform a ping without using the CFSocket APIs that now seem to be broken/unsupported on iOS 16?

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?