Hi, I see an interaction issue between a DNS Proxy system extension and MDM on macOS: after some time the device stops processing MDM commands until reboot, while DNS filtering continues to work. Environment: macOS: 15.x / 26.x (reproduced on multiple minor versions) App: /Applications/MyMacProxy.app System extension: NEDNSProxyProvider as system extension Bundle id: com.company.agent.MyMacProxy.dnsProxy Deployment: MDM (SimpleMDM) DNS proxy config via com.apple.dnsProxy.managed Devices: supervised Macs Steps to reproduce: Enrol Mac into MDM. Install MyMacProxy app + DNS proxy system extension via pkg and apply com.apple.dnsProxy.managed profile. DNS proxy starts, DNS is filtered correctly, user network works normally. After some hours, try to manage the device from MDM: push a new configuration profile, remove an existing profile, or install / remove an app. 5.MDM server shows commands as pending / not completed. On the Mac, DNS is still filtered via our DNS proxy, and general network access (Safari etc.) continues to work. After reboot, pending MDM commands are processed and we can remove the app, profile and system extension normally. This is reproducible on our test machines. What I see on the Mac in the “stuck” state apsd is running: sudo launchctl print system/com.apple.apsd # job state = running com.apple.mdmclient.daemon exists as a job but is not running: sudo launchctl print system/com.apple.mdmclient.daemon Abbreviated output: system/com.apple.mdmclient.daemon = { ... state = not running job state = exited runs = 5 last exit code = 0 ... } So the MDM client daemon has exited cleanly (exit code 0) and is currently not running; its APS endpoints are configured. Our DNS proxy system extension is still processing flows: we see continuous logging from our NEDNSProxyProvider, and DNS filtering is clearly active (requests go through our upstream). systemextensionsctl list still shows our DNS proxy system extension as active. From the user’s perspective, everything works (with filtered DNS). From the MDM server’s perspective, commands stay pending until the next reboot. After reboot, MDM behaviour is normal again. Uninstall / cleanup (current approach, simplified) We currently use an MDM‑delivered shell script that: disables our DNS proxy configuration for the console user by editing ~/Library/Preferences/com.apple.networkextension.plist and setting Enabled = false for our DNSProxyConfigurations entries; flushes DNS cache and restarts mDNSResponder; unloads our LaunchDaemon / LaunchAgent for the host app; kills the system extension process using pgrep -f "com.company.agent.MyMacProxy.dnsProxy" | xargs kill -9; removes the extension binary from /Library/SystemExtensions/.../com.company.agent.MyMacProxy.dnsProxy.systemextension; removes /Applications/MyMacProxy.app and related support files. We currently do not call systemextensionsctl uninstall <TEAMID> com.company.agent.MyMacProxy.dnsProxy from MDM, mainly because of SIP and because we understand that fully silent system extension uninstall is constrained. The MDM responsiveness issue, however, can appear even if we don’t run this aggressive uninstall script and just let the extension run for some hours. Questions Is it expected that a DNS Proxy system extension (managed via com.apple.dnsProxy.managed) can leave a device in a state where: apsd is running, com.apple.mdmclient.daemon is not running (last exit code 0), DNS proxy continues to filter traffic, but MDM commands remain pending until reboot? Are there known best practices or pitfalls when combining: DNS Proxy system extensions (NEDNSProxyProvider), MDM‑distributed com.apple.dnsProxy.managed profiles, and MDM app / profile management on recent macOS versions? For uninstall in an MDM environment, what pattern do you recommend? For example, is it better to: disable / remove the DNS proxy profile, stop the NE configuration via NEDNSProxyManager from the app, avoid killing the system extension or removing files from /Library/SystemExtensions immediately, and instead require a reboot for full removal? I can provide a sysdiagnose and unified logs (including nesessionmanager, mdmclient and our logs) from an affected machine if that would be helpful.

I'm implementing a NEDNSProxyProvider on macOS 15.x and macOS 26.x. The flow works correctly up to the last step — returning the DNS response to the client via writeDatagrams. Environment: macOS 15.x, 26.x Xcode 26.x NEDNSProxyProvider with NEAppProxyUDPFlow What I'm doing: override func handleNewFlow(_ flow: NEAppProxyFlow) -> Bool { guard let udpFlow = flow as? NEAppProxyUDPFlow else { return false } udpFlow.readDatagrams { datagrams, endpoints, error in // 1. Read DNS request from client // 2. Forward to upstream DNS server via TCP // 3. Receive response from upstream // 4. Try to return response to client: udpFlow.writeDatagrams([responseData], sentBy: [endpoints.first!]) { error in // Always fails: "The datagram was too large" // responseData is 50-200 bytes — well within UDP limits } } return true } Investigation: I added logging to check the type of endpoints.first : // On macOS 15.0 and 26.3.1: // type(of: endpoints.first) → NWAddressEndpoint // Not NWHostEndpoint as expected On both macOS 15.4 and 26.3.1, readDatagrams returns [NWEndpoint] where each endpoint appears to be NWAddressEndpoint — a type that is not publicly documented. When I try to create NWHostEndpoint manually from hostname and port, and pass it to writeDatagrams, the error "The datagram was too large" still occurs in some cases. Questions: What is the correct endpoint type to pass to writeDatagrams on macOS 15.x, 26.x? Should we pass the exact same NWEndpoint objects returned by readDatagrams, or create new ones? NWEndpoint, NWHostEndpoint, and writeDatagrams are all deprecated in macOS 15. Is there a replacement API for NEAppProxyUDPFlow that works with nw_endpoint_t from the Network framework? Is the error "The datagram was too large" actually about the endpoint type rather than the data size? Any guidance would be appreciated. :-))

I’m building a macOS app with a DNS Proxy system extension for Developer ID + notarization, deployed via MDM, and Xcode fails the Developer ID Release build with a provisioning profile mismatch for com.apple.developer.networking.networkextension. Environment macOS: Sequoia (15.7.2) Xcode: 26.2 Distribution: Developer ID + notarization, deployed via MDM Host bundle ID: com.mydns.agent.MyDNSMacProxy DNS Proxy system extension bundle ID: com.mydns.agent.MyDNSMacProxy.dnsProxy Host entitlements (Release): File: MyDNSMacProxy/MyDNSMacProxyRelease.entitlements: "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>com.apple.application-identifier</key> <string>B234657989.com.mydns.agent.MyDNSMacProxy</string> <key>com.apple.developer.networking.networkextension</key> <array> <string>dns-proxy</string> </array> <key>com.apple.developer.system-extension.install</key> <true/> <key>com.apple.developer.team-identifier</key> <string>B234657989</string> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.application-groups</key> <array> <string>group.com.mydns.MyDNSmac</string> </array> <key>keychain-access-groups</key> <array> <string>B234657989.*</string> </array> </dict> </plist> xcodebuild -showBuildSettings -scheme MyDNSMacProxy -configuration Release : PROVISIONING_PROFILE_SPECIFIER = main MyDNSMacProxy5 CODE_SIGN_IDENTITY = Developer ID Application Host Developer ID profile main_MyDNSMacProxy5.provisionprofile (via security cms -D): "Entitlements" => { "com.apple.application-identifier" => "B234657989.com.mydns.agent.MyDNSMacProxy" "com.apple.developer.team-identifier" => "B234657989" "com.apple.security.application-groups" => [ "group.com.mydns.MyDNSmac", ..., "B234657989.*" ] "keychain-access-groups" => [ "B234657989.*" ] "com.apple.developer.system-extension.install" => 1 "com.apple.developer.networking.networkextension" => [ "packet-tunnel-provider-systemextension", "app-proxy-provider-systemextension", "content-filter-provider-systemextension", "dns-proxy-systemextension", "dns-settings", "relay", "url-filter-provider", "hotspot-provider" ] } So: App ID, team ID, keychain and system‑extension.install match. The profile’s com.apple.developer.networking.networkextension is a superset of what I request in the host entitlements (dns-proxy only). System extension (for context) DNS Proxy system extension target: NSExtensionPointIdentifier = com.apple.dns-proxy NetworkExtension → NEProviderClasses → com.apple.networkextension.dns-proxy → my provider class Entitlements: com.apple.developer.networking.networkextension = ["dns-proxy-systemextension"] This target uses a separate Developer ID profile and builds successfully. Xcode error Release build of the host fails with: …MyDNSMacProxy.xcodeproj: error: Provisioning profile "main MyDNSMacProxy5" doesn't match the entitlements file's value for the com.apple.developer.networking.networkextension entitlement. (in target 'MyDNSMacProxy' from project 'MyDNSMacProxy') Xcode UI also says: Entitlements: 6 Included, 1 Missing Includes com.apple.developer.team-identifier, com.apple.application-identifier, keychain-access-groups, com.apple.developer.system-extension.install, and com.apple.security.application-groups. Doesn’t match entitlements file value for com.apple.developer.networking.networkextension. Because of this, the app bundle isn’t produced and I can’t inspect the final signed entitlements. Questions: For com.apple.developer.networking.networkextension, should Xcode accept a subset of values in the entitlements (here just dns-proxy) as long as that value is allowed by the Developer ID profile, or does it currently require a stricter match? Is the following configuration valid for Developer ID + MDM with a DNS Proxy system extension: Host entitlements: ["dns-proxy"] System extension entitlements: ["dns-proxy-systemextension"] Host profile’s NE array includes the DNS Proxy system extension types. If this is a known limitation or bug in how Xcode validates NE entitlements for Developer ID, is there a recommended workaround? Thanks for any guidance.

Hi, I’m implementing a macOS DNS Proxy as a system extension and running into a persistent activation error: OSSystemExtensionErrorDomain error 9 (validationFailed) with the message: extension category returned error This happens both on an MDM‑managed Mac and on a completely clean Mac (no MDM, fresh install). Setup macOS: 15.x (clean machine, no MDM) Xcode: 16.x Team ID: AAAAAAA111 (test) Host app bundle ID: com.example.agent.NetShieldProxy DNS Proxy system extension bundle ID: com.example.agent.NetShieldProxy.dnsProxy The DNS Proxy is implemented as a NetworkExtension system extension, not an app extension. Host app entitlements From codesign -d --entitlements :- /Applications/NetShieldProxy.app: xml com.apple.application-identifier AAAAAAA111.com.example.agent.NetShieldProxy <key>com.apple.developer.system-extension.install</key> <true/> <key>com.apple.developer.team-identifier</key> <string>AAAAAAA111</string> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.application-groups</key> <array> <string>group.com.example.NetShieldmac</string> </array> <key>com.apple.security.files.user-selected.read-only</key> <true/> xml com.apple.application-identifier AAAAAAA111.com.example.agent.NetShieldProxy.dnsProxy <key>com.apple.developer.networking.networkextension</key> <array> <string>dns-proxy-systemextension</string> </array> <key>com.apple.developer.team-identifier</key> <string>AAAAAAA111</string> <key>com.apple.security.application-groups</key> <array> <string>group.com.example.NetShieldmac</string> <string>group.example.NetShieldmac</string> <string>group.example.agent.enterprise.macos</string> <string>group.example.com.NetShieldmac</string> </array> DNS Proxy system extension Info.plist On the clean Mac, from: bash plutil -p "/Applications/NetShieldProxy.app/Contents/Library/SystemExtensions/com.example.agent.NetShieldProxy.dnsProxy.systemextension/Contents/Info.plist" I get: json { "CFBundleExecutable" => "com.example.agent.NetShieldProxy.dnsProxy", "CFBundleIdentifier" => "com.example.agent.NetShieldProxy.dnsProxy", "CFBundleName" => "com.example.agent.NetShieldProxy.dnsProxy", "CFBundlePackageType" => "SYSX", "CFBundleShortVersionString" => "1.0.1.8", "CFBundleSupportedPlatforms" => [ "MacOSX" ], "CFBundleVersion" => "0.1.1", "LSMinimumSystemVersion" => "13.5", "NSExtension" => { "NSExtensionPointIdentifier" => "com.apple.dns-proxy", "NSExtensionPrincipalClass" => "com_example_agent_NetShieldProxy_dnsProxy.DNSProxyProvider" }, "NSSystemExtensionUsageDescription" => "SYSTEM_EXTENSION_USAGE_DESCRIPTION" } The DNSProxyProvider class inherits from NEDNSProxyProvider and is built in the system extension target. Activation code In the host app, I use: swift import SystemExtensions final class SystemExtensionActivator: NSObject, OSSystemExtensionRequestDelegate { private let extensionIdentifier = "com.example.agent.NetShieldProxy.dnsProxy" func activate(completion: @escaping (Bool) -> Void) { let request = OSSystemExtensionRequest.activationRequest( forExtensionWithIdentifier: extensionIdentifier, queue: .main ) request.delegate = self OSSystemExtensionManager.shared.submitRequest(request) } func request(_ request: OSSystemExtensionRequest, didFailWithError error: Error) { let nsError = error as NSError print("Activation failed:", nsError) } func request(_ request: OSSystemExtensionRequest, didFinishWithResult result: OSSystemExtensionRequest.Result) { print("Result:", result.rawValue) } } Runtime behavior on a clean Mac (no MDM) config.plist is created under /Library/Application Support/NetShield (via a root shell script). A daemon runs, contacts our backend, and writes /Library/Application Support/NetShield/state.plist with a valid dnsToken and other fields. The app NetShieldProxy.app is installed via a notarized, stapled Developer ID .pkg. The extension bundle is present at: /Applications/NetShieldProxy.app/Contents/Library/SystemExtensions/com.example.agent.NetShieldProxy.dnsProxy.systemextension. When I press Activate DNS Proxy in the UI, I see in the unified log: text NetShieldProxy: [com.example.agent:SystemExtensionActivator] Requesting activation for system extension: com.example.agent.NetShieldProxy.dnsProxy NetShieldProxy: [com.example.agent:SystemExtensionActivator] SystemExtensionActivator - activation failed: extension category returned error (domain=OSSystemExtensionErrorDomain code=9) NetShieldProxy: [com.example.agent:SystemExtensionActivator] SystemExtensionActivator - OSSystemExtensionError code enum: 9 NetShieldProxy: [com.example.agent:SystemExtensionActivator] SystemExtensionActivator - validationFailed And: bash systemextensionsctl list -> 0 extension(s) There is no prompt in Privacy & Security on this clean Mac. Question Given: The extension is packaged as a system extension (CFBundlePackageType = SYSX) with NSExtensionPointIdentifier = "com.apple.dns-proxy". Host and extension share the same Team ID and Developer ID Application cert. Entitlements on the target machine match the provisioning profile and Apple’s docs for DNS Proxy system extensions (dns-proxy-systemextension). This is happening on a clean Mac with no MDM profiles at all. What are the likely reasons for OSSystemExtensionErrorDomain error 9 (validationFailed) with "extension category returned error" in this DNS Proxy system extension scenario? Is there any additional configuration required for DNS Proxy system extensions (beyond entitlements and Info.plist) that could trigger this category-level validation failure? Any guidance or examples of a working DNS Proxy system extension configuration (host entitlements + extension Info.plist + entitlements) would be greatly appreciated. Thanks!