diff --git a/core/adapter.go b/core/adapter/adapter.go
similarity index 92%
rename from core/adapter.go
rename to core/adapter/adapter.go
index ea184c0..e4e4296 100644
--- a/core/adapter.go
+++ b/core/adapter/adapter.go
@@ -1,4 +1,4 @@
-package core
+package adapter
 
 import (
 	"net"
diff --git a/core/handler.go b/core/adapter/handler.go
similarity index 91%
rename from core/handler.go
rename to core/adapter/handler.go
index 0a9345d..2878b71 100644
--- a/core/handler.go
+++ b/core/adapter/handler.go
@@ -1,4 +1,4 @@
-package core
+package adapter
 
 // Handler is a TCP/UDP connection handler that implements
 // HandleTCPConn and HandleUDPConn methods.
diff --git a/core/stack/stack.go b/core/stack/stack.go
index a1c46e6..d9b4770 100644
--- a/core/stack/stack.go
+++ b/core/stack/stack.go
@@ -2,7 +2,7 @@
 package stack
 
 import (
-	"github.com/xjasonlyu/tun2socks/v2/core"
+	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
@@ -16,12 +16,12 @@ import (
 type Stack struct {
 	*stack.Stack
 
-	handler core.Handler
+	handler adapter.Handler
 	nicID   tcpip.NICID
 }
 
 // New allocates a new *Stack with given options.
-func New(ep stack.LinkEndpoint, handler core.Handler, opts ...Option) (*Stack, error) {
+func New(ep stack.LinkEndpoint, handler adapter.Handler, opts ...Option) (*Stack, error) {
 	s := &Stack{
 		Stack: stack.New(stack.Options{
 			NetworkProtocols: []stack.NetworkProtocolFactory{
diff --git a/engine/tunnel.go b/engine/tunnel.go
index 627d6c3..fde0017 100644
--- a/engine/tunnel.go
+++ b/engine/tunnel.go
@@ -1,18 +1,18 @@
 package engine
 
 import (
-	"github.com/xjasonlyu/tun2socks/v2/core"
+	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 	"github.com/xjasonlyu/tun2socks/v2/tunnel"
 )
 
-var _ core.Handler = (*fakeTunnel)(nil)
+var _ adapter.Handler = (*fakeTunnel)(nil)
 
 type fakeTunnel struct{}
 
-func (*fakeTunnel) HandleTCPConn(conn core.TCPConn) {
+func (*fakeTunnel) HandleTCPConn(conn adapter.TCPConn) {
 	tunnel.TCPIn() <- conn
 }
 
-func (*fakeTunnel) HandleUDPConn(conn core.UDPConn) {
+func (*fakeTunnel) HandleUDPConn(conn adapter.UDPConn) {
 	tunnel.UDPIn() <- conn
 }
diff --git a/tunnel/tcp.go b/tunnel/tcp.go
index 792c738..e0a7017 100644
--- a/tunnel/tcp.go
+++ b/tunnel/tcp.go
@@ -7,7 +7,7 @@ import (
 	"time"
 
 	"github.com/xjasonlyu/tun2socks/v2/common/pool"
-	"github.com/xjasonlyu/tun2socks/v2/core"
+	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 	"github.com/xjasonlyu/tun2socks/v2/log"
 	M "github.com/xjasonlyu/tun2socks/v2/metadata"
 	"github.com/xjasonlyu/tun2socks/v2/proxy"
@@ -22,7 +22,7 @@ func newTCPTracker(conn net.Conn, metadata *M.Metadata) net.Conn {
 	return statistic.NewTCPTracker(conn, metadata, statistic.DefaultManager)
 }
 
-func handleTCPConn(localConn core.TCPConn) {
+func handleTCPConn(localConn adapter.TCPConn) {
 	defer localConn.Close()
 
 	var (
diff --git a/tunnel/tunnel.go b/tunnel/tunnel.go
index a8e2346..8ced53f 100644
--- a/tunnel/tunnel.go
+++ b/tunnel/tunnel.go
@@ -1,13 +1,13 @@
 package tunnel
 
 import (
-	"github.com/xjasonlyu/tun2socks/v2/core"
+	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 )
 
 // Unbuffered TCP/UDP queues.
 var (
-	_tcpQueue = make(chan core.TCPConn)
-	_udpQueue = make(chan core.UDPConn)
+	_tcpQueue = make(chan adapter.TCPConn)
+	_udpQueue = make(chan adapter.UDPConn)
 )
 
 func init() {
@@ -15,12 +15,12 @@ func init() {
 }
 
 // TCPIn return fan-in TCP queue.
-func TCPIn() chan<- core.TCPConn {
+func TCPIn() chan<- adapter.TCPConn {
 	return _tcpQueue
 }
 
 // UDPIn return fan-in UDP queue.
-func UDPIn() chan<- core.UDPConn {
+func UDPIn() chan<- adapter.UDPConn {
 	return _udpQueue
 }
 
diff --git a/tunnel/udp.go b/tunnel/udp.go
index 504abc3..57593a1 100644
--- a/tunnel/udp.go
+++ b/tunnel/udp.go
@@ -7,7 +7,7 @@ import (
 	"time"
 
 	"github.com/xjasonlyu/tun2socks/v2/common/pool"
-	"github.com/xjasonlyu/tun2socks/v2/core"
+	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 	"github.com/xjasonlyu/tun2socks/v2/log"
 	M "github.com/xjasonlyu/tun2socks/v2/metadata"
 	"github.com/xjasonlyu/tun2socks/v2/proxy"
@@ -25,7 +25,7 @@ func newUDPTracker(conn net.PacketConn, metadata *M.Metadata) net.PacketConn {
 	return statistic.NewUDPTracker(conn, metadata, statistic.DefaultManager)
 }
 
-func handleUDPConn(uc core.UDPConn) {
+func handleUDPConn(uc adapter.UDPConn) {
 	defer uc.Close()
 
 	var (
@@ -55,7 +55,7 @@ func handleUDPConn(uc core.UDPConn) {
 	handleUDPToLocal(uc, pc, remote)
 }
 
-func handleUDPToRemote(uc core.UDPConn, pc net.PacketConn, remote net.Addr) {
+func handleUDPToRemote(uc adapter.UDPConn, pc net.PacketConn, remote net.Addr) {
 	buf := pool.Get(pool.MaxSegmentSize)
 	defer pool.Put(buf)
 
@@ -74,7 +74,7 @@ func handleUDPToRemote(uc core.UDPConn, pc net.PacketConn, remote net.Addr) {
 	}
 }
 
-func handleUDPToLocal(uc core.UDPConn, pc net.PacketConn, remote net.Addr) {
+func handleUDPToLocal(uc adapter.UDPConn, pc net.PacketConn, remote net.Addr) {
 	buf := pool.Get(pool.MaxSegmentSize)
 	defer pool.Put(buf)