diff --git a/Tun/Punchnet/SDLIPV6AssistClient.swift b/Tun/Punchnet/SDLIPV6AssistClient.swift
index 345feaa..5ab0637 100644
--- a/Tun/Punchnet/SDLIPV6AssistClient.swift
+++ b/Tun/Punchnet/SDLIPV6AssistClient.swift
@@ -8,19 +8,81 @@ import Foundation
 import Network
 
 actor SDLIPV6AssistClient {
+    
+    struct Packet: Sendable {
+        enum IPVersion: UInt8, Sendable {
+            case ipv4 = 4
+            case ipv6 = 6
+            
+            var protocolFamily: Int32 {
+                switch self {
+                case .ipv4:
+                    return 2
+                case .ipv6:
+                    return 30
+                }
+            }
+        }
+        
+        let packetId: UInt32
+        let ipPacketData: Data
+        let ipVersion: IPVersion
+        
+        var protocolFamily: Int32 {
+            return self.ipVersion.protocolFamily
+        }
+    }
+    
     private enum State {
         case idle
         case running
         case stopped
     }
     
+    private struct PendingPacket: Sendable {
+        let packetId: UInt32
+        let ipVersion: Packet.IPVersion
+    }
+    
+    private enum PacketParseError: Error {
+        case packetTooShort
+        case unmatchedPacketId(UInt32)
+        case invalidIPVersion(UInt8)
+        case unsupportedIPVersion(UInt8)
+    }
+    
     private var state: State = .idle
     private var connection: NWConnection?
     private var receiveTask: Task<Void, Never>?
     private let assistServerAddress: NWEndpoint
+    private var idGenerator: SDLIdGenerator
+    private var pendingPackets: [UInt32: PendingPacket] = [:]
     
-    init(host: String, port: UInt16 ) {
-        self.assistServerAddress = .hostPort(host: NWEndpoint.Host(host), port: NWEndpoint.Port(integerLiteral: port))
+    // 用于对外输出收到的原始 IP 响应包
+    let packetFlow: AsyncStream<Packet>
+    private let packetContinuation: AsyncStream<Packet>.Continuation
+    private var didFinishPacketFlow = false
+    
+    // 用来处理关闭事件
+    private let closeStream: AsyncStream<Void>
+    private let closeContinuation: AsyncStream<Void>.Continuation
+    private var didFinishCloseStream = false
+    
+    init?(assistServerInfo: SDLV6Info) {
+        guard assistServerInfo.port <= UInt32(UInt16.max), let host = SDLUtil.ipv6DataToString(assistServerInfo.v6) else {
+            return nil
+        }
+        
+        let (packetStream, packetContinuation) = AsyncStream.makeStream(of: Packet.self, bufferingPolicy: .bufferingNewest(256))
+        self.packetFlow = packetStream
+        self.packetContinuation = packetContinuation
+        
+        let (closeStream, closeContinuation) = AsyncStream.makeStream(of: Void.self, bufferingPolicy: .bufferingNewest(1))
+        self.closeStream = closeStream
+        self.closeContinuation = closeContinuation
+        
+        self.assistServerAddress = .hostPort(host: NWEndpoint.Host(host), port: NWEndpoint.Port(integerLiteral: UInt16(assistServerInfo.port)))
+        self.idGenerator = SDLIdGenerator(seed: UInt32.random(in: 1..<UInt32.max))
     }
     
     func start() {
@@ -38,6 +100,11 @@ actor SDLIPV6AssistClient {
         // 2. 增强健壮性：启用多路径切换（替代 pathSelectionOptions 的意图）
         parameters.multipathServiceType = .handover
         
+        // 只允许走 IPv6，避免在 assist 通道上退回到 IPv4 或双栈协商。
+        if let ipOptions = parameters.defaultProtocolStack.internetProtocol as? NWProtocolIP.Options {
+            ipOptions.version = .v6
+        }
+        
         // 2. 创建连接
         let connection = NWConnection(to: self.assistServerAddress, using: parameters)
         self.connection = connection
@@ -52,6 +119,10 @@ actor SDLIPV6AssistClient {
         connection.start(queue: .global())
     }
     
+    public func waitClose() async {
+        for await _ in self.closeStream { }
+    }
+    
     /// 接收数据的递归循环
     private static func makeReceiveStream(for connection: NWConnection) -> AsyncStream<Data> {
         return AsyncStream(bufferingPolicy: .bufferingNewest(256)) { continuation in
@@ -75,16 +146,32 @@ actor SDLIPV6AssistClient {
     }
     
     /// 发送 DNS 查询包（由 TUN 拦截到的原始 IP 包数据）
-    func forward(ipPacketData: Data) {
+    /// 当前实现会在原始 IP 包前增加 4 字节的 packetId，用于建立请求和响应的对应关系。
+    @discardableResult
+    func forward(ipPacketData: Data) -> UInt32? {
         guard case .running = self.state, let connection = self.connection, connection.state == .ready else {
-            return
+            return nil
         }
         
-        connection.send(content: ipPacketData, completion: .contentProcessed { error in
-            if let error = error {
-                SDLLogger.log("[SDLIPV6AssistClient] Send error: \(error)", for: .debug)
+        let ipVersion: Packet.IPVersion
+        do {
+            ipVersion = try self.parseIPVersion(packetData: ipPacketData)
+        } catch {
+            SDLLogger.log("[SDLIPV6AssistClient] Invalid outbound packet: \(error)", for: .debug)
+            return nil
+        }
+        
+        let packetId = self.idGenerator.nextId()
+        self.pendingPackets[packetId] = .init(packetId: packetId, ipVersion: ipVersion)
+        
+        let outboundPacket = Data(components: Data(uint32: packetId), ipPacketData)
+        connection.send(content: outboundPacket, completion: .contentProcessed { [weak self] error in
+            Task {
+                await self?.handleSendCompletion(packetId: packetId, error: error)
             }
         })
+        
+        return packetId
     }
     
     func stop() {
@@ -95,8 +182,11 @@ actor SDLIPV6AssistClient {
         self.state = .stopped
         self.receiveTask?.cancel()
         self.receiveTask = nil
+        self.pendingPackets.removeAll()
         self.connection?.cancel()
         self.connection = nil
+        self.finishPacketFlowIfNeeded()
+        self.finishCloseStreamIfNeeded()
     }
     
     private func handleConnectionStateUpdate(_ state: NWConnection.State, for connection: NWConnection) {
@@ -131,6 +221,8 @@ actor SDLIPV6AssistClient {
                 }
                 await self.handleReceivedPacket(data)
             }
+            
+            await self?.didFinishReceiving(for: connection)
         }
     }
     
@@ -139,7 +231,89 @@ actor SDLIPV6AssistClient {
             return
         }
         
-        NSLog("data: \(data)")
+        do {
+            let packet = try self.parseInboundPacket(data)
+            self.packetContinuation.yield(packet)
+        } catch {
+            SDLLogger.log("[SDLIPV6AssistClient] Receive error: \(error)", for: .debug)
+        }
+    }
+    
+    private func handleSendCompletion(packetId: UInt32, error: Error?) {
+        guard case .running = self.state else {
+            return
+        }
+        
+        if let error {
+            self.pendingPackets.removeValue(forKey: packetId)
+            SDLLogger.log("[SDLIPV6AssistClient] Send error: \(error), packetId: \(packetId)", for: .debug)
+        }
+    }
+    
+    private func didFinishReceiving(for connection: NWConnection) {
+        guard case .running = self.state else {
+            return
+        }
+        
+        if self.connection === connection, connection.state != .ready {
+            self.stop()
+        } else {
+            self.receiveTask = nil
+        }
+    }
+    
+    private func parseInboundPacket(_ data: Data) throws -> Packet {
+        guard data.count > 4 else {
+            throw PacketParseError.packetTooShort
+        }
+        
+        let packetId = UInt32(data: Data(data.prefix(4)))
+        guard let pendingPacket = self.pendingPackets.removeValue(forKey: packetId) else {
+            throw PacketParseError.unmatchedPacketId(packetId)
+        }
+        
+        let ipPacketData = Data(data.dropFirst(4))
+        let ipVersion = try self.parseIPVersion(packetData: ipPacketData)
+        
+        if ipVersion != pendingPacket.ipVersion {
+            SDLLogger.log("[SDLIPV6AssistClient] packet version mismatch, packetId: \(packetId), request: \(pendingPacket.ipVersion.rawValue), response: \(ipVersion.rawValue)", for: .debug)
+        }
+        
+        return .init(packetId: pendingPacket.packetId, ipPacketData: ipPacketData, ipVersion: ipVersion)
+    }
+    
+    private func parseIPVersion(packetData: Data) throws -> Packet.IPVersion {
+        guard let firstByte = packetData.first else {
+            throw PacketParseError.packetTooShort
+        }
+        
+        let rawVersion = firstByte >> 4
+        guard let ipVersion = Packet.IPVersion(rawValue: rawVersion) else {
+            throw PacketParseError.invalidIPVersion(rawVersion)
+        }
+        guard ipVersion == .ipv6 else {
+            throw PacketParseError.unsupportedIPVersion(rawVersion)
+        }
+        
+        return ipVersion
+    }
+    
+    private func finishPacketFlowIfNeeded() {
+        guard !self.didFinishPacketFlow else {
+            return
+        }
+        
+        self.didFinishPacketFlow = true
+        self.packetContinuation.finish()
+    }
+    
+    private func finishCloseStreamIfNeeded() {
+        guard !self.didFinishCloseStream else {
+            return
+        }
+        
+        self.didFinishCloseStream = true
+        self.closeContinuation.finish()
     }
     
     deinit {