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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.

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NWPathMonitor Reports Unexpected satisfied→unsatisfied→satisfied Sequence After WiFi Re-enablement
I am developing an iOS application using NWPathMonitor for network connectivity monitoring. We discovered a reproducible issue where disabling and re-enabling WiFi triggers an unexpected network status sequence. ENVIRONMENT: iOS Version: 17.x Device: iPhone (various models tested) Network Framework: NWPathMonitor from iOS Network framework STEPS TO REPRODUCE: Device connected to WiFi normally Disable WiFi via Settings or Control Center Re-enable WiFi via Settings or Control Center EXPECTED BEHAVIOR: WiFi reconnects and NWPathMonitor reports stable satisfied status ACTUAL BEHAVIOR: T+0s: WiFi re-enables, NWPathMonitor reports path.status = .satisfied T+8s: NWPathMonitor unexpectedly reports path.status = .unsatisfied with unsatisfiedReason = .notAvailable T+9-10s: NWPathMonitor reports path.status = .satisfied again Connection becomes stable afterward NETWORK PATH TIMELINE: T+0s: satisfied (IPv4: true, DNS: false) T+140ms: satisfied (IPv4: true, DNS: true) T+8.0s: unsatisfied (reason: notAvailable, no interfaces available) T+10.0s: satisfied (IPv4: true, DNS: true) KEY OBSERVATIONS: Timing consistency: unsatisfied event always occurs ~8 seconds after reconnection resolution: "Reset Network Settings" eliminates this behavior TECHNICAL QUESTIONS: What causes the 8-second delayed unsatisfied status after WiFi re-enablement? Is this expected behavior that applications should handle? Why does reset network setting in iPhone fix this issue?
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111
Jul ’25
iOS Multiple BSSID Parsing/Inherit Behavior Issue – HS2.0 IE Handling Incorrect (Non‑Tx VAP should not inherit Tx VAP’s HS2.0 Indication)
I am experiencing issue - iphone16/17 can't connect to the non-txvap SSID when the corresponding txvap is passpoint SSID. It may always fail to connect. But when I set the non-passpoint SSID as txvap and passpoint SSID as non-txvap, then iPhone16/17 can connect to the two SSID successfully. iPhone will add “HS20=1” flag for the non-passpoint SSID, then iPhone will ALWAYS not connect that SSID successfully. Please see the log below I captured from the issue iPhone. -[WFNetworkListController _updateViewControllerScanResults]_block_invoke: removing associationCtx network <WFNetworkScanRecord : 0xd34dec8c0 ssid='!wpa3-openwrt-mim6g' bssid='00:03:7f:12:cb:cd' rssi='-80' secured=1 eap=0 mode='WPA3 Personal' modeExt=['WPA3 Personal'] hidden=0 HS20=1 popular=0 known=0 privateAddressState=1> from scan results See detail in FB20923870 Is there anybody else meet this issue?
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45
Nov ’25
Apple sample code: device-to-device connection breaks on second launch (tvOS 18.6 / iPadOS 18.3.2, 18.6)
Hello everyone, Last year I built an application for tvOS and iPadOS that enables device-to-device communication. I based it on Apple’s sample code, available here: https://developer.apple.com/documentation/Network/building-a-custom-peer-to-peer-protocol At that time, everything worked flawlessly. However, this year I had to revisit the project to add new features, and now it no longer works as expected. The first time the app runs it connects fine, but if we relaunch it (on either the iPad, the Apple TV, or both), the connection fails. Most importantly, this is not an issue with my own code — I tested it directly with the original Apple sample code, and the exact same problem occurs there too. Here’s what I see in the logs: nw_endpoint_flow_setup_channel [C1 TicTacToe,65E91B02-890E-4D30-88B8-CE2AB9677BF9 in_progress channel-flow (satisfied (Path is satisfied), viable, interface: utun0, scoped, ipv6)] nexus assignment error Connection refused nw_endpoint_flow_failed_with_error [C1 TicTacToe,65E91B02-890E-4D30-88B8-CE2AB9677BF9 in_progress channel-flow (satisfied (Path is satisfied), viable, interface: utun0, scoped, ipv6)] already failing, returning code-block This happens right after I select the iPad from the device list and try to connect. What’s strange is that the interface being used is utun0. I don’t have a VPN or iCloud Private Relay enabled. I also tried running the app through the iPad’s personal hotspot, but I get the same error. The only workaround I’ve found so far is to restart the Apple TV. Has anyone else run into this problem? Is there any known solution or workaround? Tested on tvOS 18.6 and iPadOS 18.3.2 / 18.6.
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232
Aug ’25
Is there any API or entitlement to scan available Wi-Fi networks on iOS (Xcode 15 / iOS 17+)?
Hello, I’m developing an iOS app with Xcode (Objective-C / Swift), and I would like to know if there is any supported way to retrieve a list of nearby Wi-Fi networks (their SSID and signal strength). I know that NEHotspotConfigurationManager allows to configure a specific network, and the Access WiFi Information entitlement allows getting the current connected network. But is there any API (public, private, or special entitlement) that allows scanning nearby Wi-Fi networks — even for limited purposes like configuration of IoT equipment, or MFi devices? I have seen some apps doing this in the past (probably via private API), but I want to know what is the current official solution. Thanks a lot!
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123
Jun ’25
Getting WIFI SSID
Greetings I'm trying to get on iPad the SSID from the wifi I'm connected to. For that, I added the wifi entitlement and I'm requesting permission to the user for Location. Once I have it, I'm using the function CNCopySupportedInterfaces to get the interfaces, but I can only receive the en0, which using the method CNCopyCurrentNetworkInfo returns nil. I also tried using the NEHotspotNetwork.fetchCurrent and the SSID keeps being nil. So right now I'm drawing a blank. Is there any way to make it work? Thanks.
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417
May ’25
in-addr.arpa default search domains
Hi, I observed some unexpected behavior and hope that someone can enlighten me as to what this is about: mDNSResponder prepends IP / network based default search domains that are checked before any other search domain. E.g. 0.1.168.192.in-addr.arpa. would be used for an interface with an address in the the 192.168.1.0/24 subnet. This is done for any configured non-link-local IP address. I tried to find any mention of an approach like this in RFCs but couldn't spot anything. Please note that this is indeed a search domain and different from reverse-DNS lookups. Example output of tcpdump for ping devtest: 10:02:13.850802 IP (tos 0x0, ttl 64, id 43461, offset 0, flags [none], proto UDP (17), length 92) 192.168.1.2.52319 &gt; 192.168.1.1.53: 54890+ [1au] A? devtest.0.1.168.192.in-addr.arpa. (64) I was able to identify the code that adds those default IP subnet based search domains but failed to spot any indication as to what this is about: https://github.com/apple-oss-distributions/mDNSResponder/blob/d5029b5/mDNSMacOSX/mDNSMacOSX.c#L4171-L4211 Does anyone here have an ideas as to what this might be about?
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772
Apr ’25
Non-functioning IP_RECVIF on sockets proxied with NETransparentProxyProvider
Hi! I've noticed that the IP_RECVIF socket option, i.e.: int y = 1; setsockopt(fd, IPPROTO_IP, IP_RECVIF, &y, sizeof(y)); does not seem to work if the socket is proxied by a NETransparentProxyProvider type network extension: there's no ancillary data in messages received with recvmsg. As soon as I disable the network extension, recvmsg starts returning ancillary data containing the interface name. This seems to break some applications which rely on IP_RECVIF in the presence of a transparent proxy, making it, in fact, not transparent. One such example is Apple's own libresolv, which relies on IP_RECVIF and breaks if there's no ancillary data in the recvmsg result. I don't think that this is the intended behaviour, since IPV6_PKTINFO seems to work fine. I've filed a bug report (FB17586550) about this, however, I would greatly appreciate if someone could point me in the direction of a workaround.
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253
May ’25
NEURLFilterManager Error 2 in macOS - How to Validate Configuration Parameters for setConfiguration or saveToPreferences
I'm currently testing URLFilter for use in a macOS product. After calling loadFromPreferences, I set the following configuration parameters: pirServerURL = URL(string: "http://localhost:8080")! pirAuthenticationToken = "AAAA" controlProviderBundleIdentifier = "{extension app bundle identifier}" However, when I call saveToPreferences, I get an Invalid Configuration error. Is there a way to determine which parameter is invalid or incorrectly set? Also, I would appreciate any macOS-specific examples of using NEURLFilterManager, as most of the documentation I’ve found seems to focus on iOS. Thank you.
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86
Nov ’25
Happy Eyeballs cancels also-ran only after WebSocket handshake (duplicate WS sessions)
Network.framework: Happy Eyeballs cancels also-ran only after WebSocket handshake (duplicate WS sessions) Hi everyone 👋 When using NWConnection with NWProtocolWebSocket, I’ve noticed that Happy Eyeballs cancels the losing connection only after the WebSocket handshake completes on the winning path. As a result, both IPv4 and IPv6 attempts can send the GET / Upgrade request in parallel, which may cause duplicate WebSocket sessions on the server. Standards context RFC 8305 §6 (Happy Eyeballs v2) states: Once one of the connection attempts succeeds (generally when the TCP handshake completes), all other connections attempts that have not yet succeeded SHOULD be canceled. This “SHOULD” is intentionally non-mandatory — implementations may reasonably delay cancellation to account for additional factors (e.g. TLS success or ALPN negotiation). So Network.framework’s current behavior — canceling after the WebSocket handshake — is technically valid, but it can have practical side effects at the application layer. Why this matters WebSocket upgrades are semantically HTTP GET requests (RFC 6455 §4.1). Per RFC 9110 §9.2, GET requests are expected to be safe and idempotent — they should not have side effects on the server. In practice, though, WebSocket upgrades often: include Authorization headers or cookies create authenticated or persistent sessions So if both IPv4 and IPv6 paths reach the upgrade stage, the server may create duplicate sessions before one connection is canceled. Questions / Request Is there a way to make Happy Eyeballs cancel the losing path earlier — for example, right after TCP or TLS handshake — when using NWProtocolWebSocket? If not, could Apple consider adding an option (e.g. in NWProtocolWebSocket.Options) to control the cancellation threshold, such as: after TCP handshake after TLS handshake after protocol handshake (current behavior) That would align the implementation more closely with RFC 8305 and help prevent duplicate, non-idempotent upgrade requests. Context I’m aware of Quinn’s post Understanding Also-Ran Connections. This report focuses specifically on the cancellation timing for NWProtocolWebSocket and the impact of duplicate upgrade requests. Although RFC 6455 and RFC 9110 define WebSocket upgrades as safe and idempotent HTTP GETs, in practice they often establish authenticated or stateful sessions. Thus, delaying cancellation until after the upgrade can create duplicate sessions — even though the behavior is technically RFC-compliant. Happy to share a sysdiagnose and sample project via Feedback if helpful. Thanks! 🙏 Example log output With Network Link Conditioner (Edge): log stream --info --predicate 'subsystem == "com.apple.network" && process == "WS happy eyeballs"' 2025-11-03 17:02:48.875258 [C3] create connection to wss://echo.websocket.org:443 2025-11-03 17:02:48.878949 [C3.1] starting child endpoint 2a09:8280:1::37:b5c3:443 # IPv6 2025-11-03 17:02:48.990206 [C3.1] starting child endpoint 66.241.124.119:443 # IPv4 2025-11-03 17:03:00.251928 [C3.1.1] Socket received CONNECTED event # IPv6 TCP up 2025-11-03 17:03:00.515837 [C3.1.2] Socket received CONNECTED event # IPv4 TCP up 2025-11-03 17:03:04.543651 [C3.1.1] Output protocol connected (WebSocket) # WS ready on IPv6 2025-11-03 17:03:04.544390 [C3.1.2] nw_endpoint_handler_cancel # cancel IPv4 path 2025-11-03 17:03:04.544913 [C3.1.2] TLS warning: close_notify # graceful close IPv4
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92
Nov ’25
After creating the profile using eapolcfg and attempting to connect to the enterprise network, eapolclient connection fails.
I use eapolcfg in Apple's open source eap8021x repository to connect to the enterprise network. 1.https://github.com/gfleury/eap8021x-debug https://opensource.apple.com/source/eap8021x/eap8021x-304.100.1/ Our enterprise network authentication is PEAP. So far, I have created a profile using the following commands and have done the access. ./eapolcfg createProfile --authType PEAP --SSID myssid --securityType WPA2 --userDefinedName MyProfile ./eapolcfg setPasswordItem --password mypassword --name myname --SSID myssid ./eapolcfg startAuthentication --interface en0 --SSID myssid After I performed this series of operations, I passed BOOL success = [self.interface associateToEnterpriseNetwork:network identity:nil username:username password:password error:&amp;error]; Connection will pop up the following pop-up window, sometimes associateToEnterpriseNetwork will fail. I don't know what went wrong, is it that I missed some steps through the eapolcfg [tool?] This function also reports the following error:Error Domain=com.apple.coreWLAN.EAPOL.error Code=1 "(null)" Please answer my questions. Thank you very much
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460
Mar ’25
Expected timing/delays when triggering background URLSessionTask
My app attempts to upload events and logging data when the user backgrounds the app (i.e., when applicationDidEnterBackground is triggered) by creating an uploadTask using a URLSession with a URLSessionConfiguration.background. When uploading these events after being backgrounded, we call beginBackgroundTask on UIApplication, which gives us about 25-30 seconds before the expirationHandler gets triggered. I am noticing, however, that the expirationHandler is frequently called and no upload attempts have even started. This might be reasonable if, for example, I had other uploads in progress initiated prior to backgrounding, but this is not the case. Could someone confirm that, when initiating an uploadTask while the app is backgrounded using a backgroundSession, there's really no way to predict when that upload is going to begin? My observation is that about 10-20% of the time it does not begin within 20 seconds of backgrounding, and I have many events coming from clients in the field showing as much.
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125
Nov ’25
Retrieve Only the Certificates Presented by the Server
Is it possible using the network framework to retrieve the list of certificates presented by the host alone, and not the reconstructed chain assembled by the system? For example, in OpenSSL one can call SSL_get_peer_cert_chain which will return exactly this - a list of the certificates presented by the server. This is useful for when you may want to manually reconstruct the chain, or if the server is misconfigured (for example, is missing an intermediate cert). Is something like this possible with the network framework? If I connect to a host that I know only returns 1 certificate, the trust ref already has the reconstructed chain by the time my code is called: sec_protocol_options_set_verify_block(tlsOptions.securityProtocolOptions, { metadata, trustRef, verifyComplete in let trust = sec_trust_copy_ref(trustRef).takeRetainedValue() let numberOfCertificates = SecTrustGetCertificateCount(trust) // Returns 3 even though the server only sent 1
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105
Mar ’25
[iPadOS 26] EACCES (Permission Denied) on UDP Broadcast despite Multicast Networking Entitlement
My application (using a nested framework for networking) was working correctly on iPadOS 18, but failed to perform a UDP broadcast operation after upgrading the device to iPadOS 26. The low-level console logs consistently show a "Permission denied" error. Symptoms & Error Message: When attempting to send a UDP broadcast packet using NWConnection (or a similar low-level socket call within the framework), the connection fails immediately with the following error logged in the console: nw_socket_service_writes_block_invoke [C2:1] sendmsg(fd 6, 124 bytes) [13: Permission denied] (Error code 13 corresponds to EACCES). Verification Steps (What I have checked): Multicast Networking Entitlement is Approved and Applied: The necessary entitlement (com.apple.developer.networking.multicast) was granted by Apple. The Provisioning Profile used for signing the Host App Target has been regenerated and explicitly includes "Multicast Networking" capability (see attached screenshot). I confirmed that Entitlements cannot be added directly to the Framework Target, only the Host App Target, which is the expected behavior. Local Network Privacy is Configured: The Host App's Info.plist contains the NSLocalNetworkUsageDescription key with a clear usage string. Crucially, the Local Network Access alert does not reliably appear when the Broadcast function is first called (despite a full reinstall after OS upgrade). Even when Local Network Access is manually enabled in Settings, the Broadcast still fails with EACCES. Code Implementation: The Broadcast is attempted using NWConnection to the host 255.255.255.255 on a specific port. Request: Since all required entitlements and profiles are correct, and the failure is a low-level EACCES on a newly updated OS version, I suspect this may be a regression bug in the iPadOS 26 security sandbox when validating the Multicast Networking Entitlement against a low-level socket call (like sendmsg). Has anyone else encountered this specific Permission denied error on iPadOS 26 with a valid Multicast Entitlement, and is there a known workaround aside from switching to mDNS/Bonjour?
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219
Oct ’25