I am currently developing a custom-protocol VPN application for iOS using PacketTunnelProvider. I have also integrated an HTTP proxy service, which is launched via a dylib. The overall flow is as follows: App -> VPN TUN -> Local HTTP Proxy -> External Network I have a question: I am capturing all traffic, and normally, requests sent out by the HTTP proxy are also captured again by the VPN. However, when I send requests using createUdpSession in my code, they are not being captured by the virtual interface (TUN). What could be the reason for this? override func startTunnel(options: [String : NSObject]?, completionHandler: @escaping (Error?) -> Void) { let tunnelNetworkSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: "192.168.18.0") tunnelNetworkSettings.mtu=1400 let ipv4Settings = NEIPv4Settings(addresses: ["192.169.10.10"], subnetMasks: ["255.255.255.0"]) ipv4Settings.includedRoutes=[NEIPv4Route.default()] ipv4Settings.excludedRoutes = [NEIPv4Route(destinationAddress: "10.0.0.0", subnetMask: "255.0.0.0"), NEIPv4Route(destinationAddress: "172.16.0.0", subnetMask: "255.240.0.0"), NEIPv4Route(destinationAddress: "192.168.0.0", subnetMask: "255.255.0.0"), NEIPv4Route(destinationAddress:"127.0.0.0", subnetMask: "255.0.0.0"), ] tunnelNetworkSettings.ipv4Settings = ipv4Settings // Configure proxy settings let proxySettings = NEProxySettings() proxySettings.httpEnabled = true proxySettings.httpServer = NEProxyServer(address: "127.0.0.1", port: 7890) proxySettings.httpsEnabled = true proxySettings.httpsServer = NEProxyServer(address: "127.0.0.1", port: 7890) proxySettings.excludeSimpleHostnames = true proxySettings.exceptionList=["localhost","127.0.0.1"] tunnelNetworkSettings.proxySettings = proxySettings setTunnelNetworkSettings(tunnelNetworkSettings) { [weak self] error in if error != nil { completionHandler(error) return } completionHandler(nil) let stack = TUNInterface(packetFlow: self!.packetFlow) RawScoketFactory.TunnelProvider=self stack.register(stack: UDPDirectStack()) stack.register(stack: TCPDirectStack()) stack.start() } } NWUdpSession.swift // // NWUDPSocket.swift // supervpn // // Created by TobbyQuinn on 2025/2/3. // import Foundation import NetworkExtension import CocoaLumberjack public protocol NWUDPSocketDelegate: AnyObject{ func didReceive(data:Data,from:NWUDPSocket) func didCancel(socket:NWUDPSocket) } public class NWUDPSocket:NSObject{ private let session:NWUDPSession private let timeout:Int private var pendingWriteData: [Data] = [] private var writing = false private let queue:DispatchQueue=QueueFactory.getQueue() public weak var delegate:NWUDPSocketDelegate? public init?(host:String,port:UInt16,timeout:Int=Opt.UDPSocketActiveTimeout){ guard let udpSession = RawScoketFactory.TunnelProvider?.createUDPSession(to: NWHostEndpoint(hostname: host, port: "\(port)"), from: nil) else{ return nil } session = udpSession self.timeout=timeout super.init() session.addObserver(self, forKeyPath: #keyPath(NWUDPSession.state),options: [.new], context: nil) session.setReadHandler({ dataArray, error in self.queueCall{ guard error == nil, let dataArray = dataArray else { print("Error when reading from remote server or connection reset") return } for data in dataArray{ self.delegate?.didReceive(data: data, from: self) } } }, maxDatagrams: 32) } /** Send data to remote. - parameter data: The data to send. */ public func write(data: Data) { pendingWriteData.append(data) checkWrite() } public func disconnect() { session.cancel() } public override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) { guard keyPath == "state" else { return } switch session.state { case .cancelled: queueCall { self.delegate?.didCancel(socket: self) } case .ready: checkWrite() default: break } } private func checkWrite() { guard session.state == .ready else { return } guard !writing else { return } guard pendingWriteData.count > 0 else { return } writing = true session.writeMultipleDatagrams(self.pendingWriteData) {_ in self.queueCall { self.writing = false self.checkWrite() } } self.pendingWriteData.removeAll(keepingCapacity: true) } private func queueCall(block:@escaping ()->Void){ queue.async { block() } } deinit{ session.removeObserver(self, forKeyPath: #keyPath(NWUDPSession.state)) } }