diff --git a/Taskfile.yaml b/Taskfile.yaml
index 6535a3e..a77430a 100644
--- a/Taskfile.yaml
+++ b/Taskfile.yaml
@@ -12,7 +12,7 @@ tasks:
         sh: git rev-parse HEAD
       BUILD_DATE:
         sh: date "+%Y%m%d%H%M%S"
-    dir: ./cmd
+    dir: ./app/cmd/
     cmds:
       - |
         GOOS={{.GOOS}} GOARCH={{.GOARCH}} GOARM={{.GOARM}} GOMIPS={{.GOMIPS}} \
diff --git a/cmd/auth/external.go b/app/auth/external.go
similarity index 100%
rename from cmd/auth/external.go
rename to app/auth/external.go
diff --git a/cmd/auth/funcs.go b/app/auth/funcs.go
similarity index 86%
rename from cmd/auth/funcs.go
rename to app/auth/funcs.go
index 04e4693..63d3f50 100644
--- a/cmd/auth/funcs.go
+++ b/app/auth/funcs.go
@@ -6,11 +6,11 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/yosuke-furukawa/json5/encoding/json5"
 )
 
-func PasswordAuthFunc(rawMsg json5.RawMessage) (core.ConnectFunc, error) {
+func PasswordAuthFunc(rawMsg json5.RawMessage) (cs.ConnectFunc, error) {
 	var pwds []string
 	err := json5.Unmarshal(rawMsg, &pwds)
 	if err != nil {
@@ -34,7 +34,7 @@ func PasswordAuthFunc(rawMsg json5.RawMessage) (core.ConnectFunc, error) {
 	}, nil
 }
 
-func ExternalAuthFunc(rawMsg json5.RawMessage) (core.ConnectFunc, error) {
+func ExternalAuthFunc(rawMsg json5.RawMessage) (cs.ConnectFunc, error) {
 	var extConfig map[string]string
 	err := json5.Unmarshal(rawMsg, &extConfig)
 	if err != nil {
diff --git a/cmd/acme.go b/app/cmd/acme.go
similarity index 100%
rename from cmd/acme.go
rename to app/cmd/acme.go
diff --git a/cmd/client.go b/app/cmd/client.go
similarity index 96%
rename from cmd/client.go
rename to app/cmd/client.go
index cf3c4fa..857b068 100644
--- a/cmd/client.go
+++ b/app/cmd/client.go
@@ -11,20 +11,21 @@ import (
 	"os"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns"
+	hyHTTP "github.com/apernet/hysteria/app/http"
+	"github.com/apernet/hysteria/app/redirect"
+	"github.com/apernet/hysteria/app/relay"
+	"github.com/apernet/hysteria/app/socks5"
+	"github.com/apernet/hysteria/app/tproxy"
 
-	"github.com/apernet/hysteria/pkg/pmtud"
-	"github.com/apernet/hysteria/pkg/redirect"
+	"github.com/apernet/hysteria/core/pktconns"
+
+	"github.com/apernet/hysteria/core/pmtud"
 	"github.com/oschwald/geoip2-golang"
 	"github.com/yosuke-furukawa/json5/encoding/json5"
 
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/core"
-	hyHTTP "github.com/apernet/hysteria/pkg/http"
-	"github.com/apernet/hysteria/pkg/relay"
-	"github.com/apernet/hysteria/pkg/socks5"
-	"github.com/apernet/hysteria/pkg/tproxy"
-	"github.com/apernet/hysteria/pkg/transport"
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/transport"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/sirupsen/logrus"
 )
@@ -129,12 +130,12 @@ func client(config *clientConfig) {
 		}
 	}
 	// Client
-	var client *core.Client
+	var client *cs.Client
 	try := 0
 	up, down, _ := config.Speed()
 	for {
 		try += 1
-		c, err := core.NewClient(config.Server, auth, tlsConfig, quicConfig, pktConnFunc, up, down, config.FastOpen,
+		c, err := cs.NewClient(config.Server, auth, tlsConfig, quicConfig, pktConnFunc, up, down, config.FastOpen,
 			func(err error) {
 				if config.QuitOnDisconnect {
 					logrus.WithFields(logrus.Fields{
diff --git a/cmd/client_gpl.go b/app/cmd/client_gpl.go
similarity index 94%
rename from cmd/client_gpl.go
rename to app/cmd/client_gpl.go
index de7aa0b..dd5dad2 100644
--- a/cmd/client_gpl.go
+++ b/app/cmd/client_gpl.go
@@ -9,11 +9,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/apernet/hysteria/app/tun"
+
 	"github.com/docker/go-units"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/tun"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/sirupsen/logrus"
 )
 
@@ -34,7 +35,7 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
 `
 
-func startTUN(config *clientConfig, client *core.Client, errChan chan error) {
+func startTUN(config *clientConfig, client *cs.Client, errChan chan error) {
 	timeout := time.Duration(config.TUN.Timeout) * time.Second
 	if timeout == 0 {
 		timeout = 300 * time.Second
@@ -92,7 +93,7 @@ func startTUN(config *clientConfig, client *core.Client, errChan chan error) {
 					"src": defaultIPMasker.Mask(addr.String()),
 					"dst": defaultIPMasker.Mask(reqAddr),
 				}).Debugf("TUN %s EOF", strings.ToUpper(addr.Network()))
-			} else if err == core.ErrClosed && strings.HasPrefix(addr.Network(), "udp") {
+			} else if err == cs.ErrClosed && strings.HasPrefix(addr.Network(), "udp") {
 				logrus.WithFields(logrus.Fields{
 					"src": defaultIPMasker.Mask(addr.String()),
 					"dst": defaultIPMasker.Mask(reqAddr),
diff --git a/cmd/client_nongpl.go b/app/cmd/client_nongpl.go
similarity index 91%
rename from cmd/client_nongpl.go
rename to app/cmd/client_nongpl.go
index 7b4e5bb..417159b 100644
--- a/cmd/client_nongpl.go
+++ b/app/cmd/client_nongpl.go
@@ -4,7 +4,7 @@
 package main
 
 import (
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/sirupsen/logrus"
 )
 
@@ -31,6 +31,6 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 `
 
-func startTUN(config *clientConfig, client *core.Client, errChan chan error) {
+func startTUN(config *clientConfig, client *cs.Client, errChan chan error) {
 	logrus.Fatalln("TUN mode is only available in GPL builds. Please rebuild hysteria with -tags gpl")
 }
diff --git a/cmd/completion.go b/app/cmd/completion.go
similarity index 100%
rename from cmd/completion.go
rename to app/cmd/completion.go
diff --git a/cmd/config.go b/app/cmd/config.go
similarity index 100%
rename from cmd/config.go
rename to app/cmd/config.go
diff --git a/cmd/config_test.go b/app/cmd/config_test.go
similarity index 100%
rename from cmd/config_test.go
rename to app/cmd/config_test.go
diff --git a/cmd/ipmasker.go b/app/cmd/ipmasker.go
similarity index 100%
rename from cmd/ipmasker.go
rename to app/cmd/ipmasker.go
diff --git a/cmd/kploader.go b/app/cmd/kploader.go
similarity index 100%
rename from cmd/kploader.go
rename to app/cmd/kploader.go
diff --git a/cmd/main.go b/app/cmd/main.go
similarity index 100%
rename from cmd/main.go
rename to app/cmd/main.go
diff --git a/cmd/mmdb.go b/app/cmd/mmdb.go
similarity index 100%
rename from cmd/mmdb.go
rename to app/cmd/mmdb.go
diff --git a/cmd/resolver.go b/app/cmd/resolver.go
similarity index 98%
rename from cmd/resolver.go
rename to app/cmd/resolver.go
index a4dacb4..473712c 100644
--- a/cmd/resolver.go
+++ b/app/cmd/resolver.go
@@ -7,7 +7,7 @@ import (
 	"net/url"
 	"strings"
 
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/utils"
 	rdns "github.com/folbricht/routedns"
 )
 
diff --git a/cmd/server.go b/app/cmd/server.go
similarity index 96%
rename from cmd/server.go
rename to app/cmd/server.go
index f69b829..f4c533b 100644
--- a/cmd/server.go
+++ b/app/cmd/server.go
@@ -7,14 +7,15 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns"
+	"github.com/apernet/hysteria/app/auth"
 
-	"github.com/apernet/hysteria/cmd/auth"
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/pmtud"
-	"github.com/apernet/hysteria/pkg/sockopt"
-	"github.com/apernet/hysteria/pkg/transport"
+	"github.com/apernet/hysteria/core/pktconns"
+
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/pmtud"
+	"github.com/apernet/hysteria/core/sockopt"
+	"github.com/apernet/hysteria/core/transport"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/oschwald/geoip2-golang"
 	"github.com/prometheus/client_golang/prometheus"
@@ -90,7 +91,7 @@ func server(config *serverConfig) {
 		logrus.Info("Path MTU Discovery is not yet supported on this platform")
 	}
 	// Auth
-	var authFunc core.ConnectFunc
+	var authFunc cs.ConnectFunc
 	var err error
 	switch authMode := config.Auth.Mode; authMode {
 	case "", "none":
@@ -221,7 +222,7 @@ func server(config *serverConfig) {
 	}
 	// Server
 	up, down, _ := config.Speed()
-	server, err := core.NewServer(tlsConfig, quicConfig, pktConn,
+	server, err := cs.NewServer(tlsConfig, quicConfig, pktConn,
 		transport.DefaultServerTransport, up, down, config.DisableUDP, aclEngine,
 		connectFunc, disconnectFunc, tcpRequestFunc, tcpErrorFunc, udpRequestFunc, udpErrorFunc, promReg)
 	if err != nil {
diff --git a/cmd/update.go b/app/cmd/update.go
similarity index 100%
rename from cmd/update.go
rename to app/cmd/update.go
diff --git a/pkg/http/server.go b/app/http/server.go
similarity index 88%
rename from pkg/http/server.go
rename to app/http/server.go
index 99d9a26..5e08e12 100644
--- a/pkg/http/server.go
+++ b/app/http/server.go
@@ -7,17 +7,17 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/transport"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/transport"
+	"github.com/apernet/hysteria/core/utils"
 
 	"github.com/elazarl/goproxy/ext/auth"
 
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/elazarl/goproxy"
 )
 
-func NewProxyHTTPServer(hyClient *core.Client, transport *transport.ClientTransport, idleTimeout time.Duration,
+func NewProxyHTTPServer(hyClient *cs.Client, transport *transport.ClientTransport, idleTimeout time.Duration,
 	aclEngine *acl.Engine,
 	basicAuthFunc func(user, password string) bool,
 	newDialFunc func(reqAddr string, action acl.Action, arg string),
diff --git a/pkg/redirect/origdst_linux.go b/app/redirect/origdst_linux.go
similarity index 100%
rename from pkg/redirect/origdst_linux.go
rename to app/redirect/origdst_linux.go
diff --git a/pkg/redirect/origdst_linux_386.go b/app/redirect/origdst_linux_386.go
similarity index 100%
rename from pkg/redirect/origdst_linux_386.go
rename to app/redirect/origdst_linux_386.go
diff --git a/pkg/redirect/tcp_linux.go b/app/redirect/tcp_linux.go
similarity index 91%
rename from pkg/redirect/tcp_linux.go
rename to app/redirect/tcp_linux.go
index 7fcef90..0845690 100644
--- a/pkg/redirect/tcp_linux.go
+++ b/app/redirect/tcp_linux.go
@@ -7,12 +7,12 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/utils"
 )
 
 type TCPRedirect struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	ListenAddr *net.TCPAddr
 	Timeout    time.Duration
 
@@ -20,7 +20,7 @@ type TCPRedirect struct {
 	ErrorFunc func(addr, reqAddr net.Addr, err error)
 }
 
-func NewTCPRedirect(hyClient *core.Client, listen string, timeout time.Duration,
+func NewTCPRedirect(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr),
 	errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*TCPRedirect, error) {
diff --git a/pkg/redirect/tcp_stub.go b/app/redirect/tcp_stub.go
similarity index 75%
rename from pkg/redirect/tcp_stub.go
rename to app/redirect/tcp_stub.go
index d7bdd99..353abb1 100644
--- a/pkg/redirect/tcp_stub.go
+++ b/app/redirect/tcp_stub.go
@@ -8,12 +8,12 @@ import (
 	"net"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 )
 
 type TCPRedirect struct{}
 
-func NewTCPRedirect(hyClient *core.Client, listen string, timeout time.Duration,
+func NewTCPRedirect(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr),
 	errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*TCPRedirect, error) {
diff --git a/pkg/relay/tcp.go b/app/relay/tcp.go
similarity index 85%
rename from pkg/relay/tcp.go
rename to app/relay/tcp.go
index 1852e1c..d09ce9b 100644
--- a/pkg/relay/tcp.go
+++ b/app/relay/tcp.go
@@ -4,12 +4,12 @@ import (
 	"net"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/utils"
 )
 
 type TCPRelay struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	ListenAddr *net.TCPAddr
 	Remote     string
 	Timeout    time.Duration
@@ -18,7 +18,7 @@ type TCPRelay struct {
 	ErrorFunc func(addr net.Addr, err error)
 }
 
-func NewTCPRelay(hyClient *core.Client, listen, remote string, timeout time.Duration,
+func NewTCPRelay(hyClient *cs.Client, listen, remote string, timeout time.Duration,
 	connFunc func(addr net.Addr), errorFunc func(addr net.Addr, err error),
 ) (*TCPRelay, error) {
 	tAddr, err := net.ResolveTCPAddr("tcp", listen)
diff --git a/pkg/relay/udp.go b/app/relay/udp.go
similarity index 93%
rename from pkg/relay/udp.go
rename to app/relay/udp.go
index 8941b50..a165c32 100644
--- a/pkg/relay/udp.go
+++ b/app/relay/udp.go
@@ -7,7 +7,7 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 )
 
 const udpBufferSize = 4096
@@ -15,7 +15,7 @@ const udpBufferSize = 4096
 var ErrTimeout = errors.New("inactivity timeout")
 
 type UDPRelay struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	ListenAddr *net.UDPAddr
 	Remote     string
 	Timeout    time.Duration
@@ -24,7 +24,7 @@ type UDPRelay struct {
 	ErrorFunc func(addr net.Addr, err error)
 }
 
-func NewUDPRelay(hyClient *core.Client, listen, remote string, timeout time.Duration,
+func NewUDPRelay(hyClient *cs.Client, listen, remote string, timeout time.Duration,
 	connFunc func(addr net.Addr), errorFunc func(addr net.Addr, err error),
 ) (*UDPRelay, error) {
 	uAddr, err := net.ResolveUDPAddr("udp", listen)
@@ -46,7 +46,7 @@ func NewUDPRelay(hyClient *core.Client, listen, remote string, timeout time.Dura
 }
 
 type connEntry struct {
-	HyConn   core.HyUDPConn
+	HyConn   cs.HyUDPConn
 	Deadline atomic.Value
 }
 
diff --git a/pkg/socks5/server.go b/app/socks5/server.go
similarity index 97%
rename from pkg/socks5/server.go
rename to app/socks5/server.go
index 575762f..58255d8 100644
--- a/pkg/socks5/server.go
+++ b/app/socks5/server.go
@@ -6,10 +6,10 @@ import (
 	"fmt"
 	"strconv"
 
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/transport"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/transport"
+	"github.com/apernet/hysteria/core/utils"
 )
 
 import (
@@ -27,7 +27,7 @@ var (
 )
 
 type Server struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	Transport  *transport.ClientTransport
 	AuthFunc   func(username, password string) bool
 	Method     byte
@@ -44,7 +44,7 @@ type Server struct {
 	tcpListener *net.TCPListener
 }
 
-func NewServer(hyClient *core.Client, transport *transport.ClientTransport, addr string,
+func NewServer(hyClient *cs.Client, transport *transport.ClientTransport, addr string,
 	authFunc func(username, password string) bool, tcpTimeout time.Duration,
 	aclEngine *acl.Engine, disableUDP bool,
 	tcpReqFunc func(addr net.Addr, reqAddr string, action acl.Action, arg string),
@@ -320,7 +320,7 @@ func (s *Server) handleUDP(c *net.TCPConn, r *socks5.Request) error {
 	return nil
 }
 
-func (s *Server) udpServer(clientConn *net.UDPConn, localRelayConn *net.UDPConn, hyUDP core.HyUDPConn) {
+func (s *Server) udpServer(clientConn *net.UDPConn, localRelayConn *net.UDPConn, hyUDP cs.HyUDPConn) {
 	var clientAddr *net.UDPAddr
 	buf := make([]byte, udpBufferSize)
 	// Local to remote
diff --git a/pkg/tproxy/tcp_linux.go b/app/tproxy/tcp_linux.go
similarity index 88%
rename from pkg/tproxy/tcp_linux.go
rename to app/tproxy/tcp_linux.go
index 2c8f822..c090a97 100644
--- a/pkg/tproxy/tcp_linux.go
+++ b/app/tproxy/tcp_linux.go
@@ -5,12 +5,12 @@ import (
 	"time"
 
 	"github.com/LiamHaworth/go-tproxy"
-	"github.com/apernet/hysteria/pkg/core"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/cs"
+	"github.com/apernet/hysteria/core/utils"
 )
 
 type TCPTProxy struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	ListenAddr *net.TCPAddr
 	Timeout    time.Duration
 
@@ -18,7 +18,7 @@ type TCPTProxy struct {
 	ErrorFunc func(addr, reqAddr net.Addr, err error)
 }
 
-func NewTCPTProxy(hyClient *core.Client, listen string, timeout time.Duration,
+func NewTCPTProxy(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr),
 	errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*TCPTProxy, error) {
diff --git a/pkg/tproxy/tcp_stub.go b/app/tproxy/tcp_stub.go
similarity index 74%
rename from pkg/tproxy/tcp_stub.go
rename to app/tproxy/tcp_stub.go
index a4059b7..5f4f30d 100644
--- a/pkg/tproxy/tcp_stub.go
+++ b/app/tproxy/tcp_stub.go
@@ -8,12 +8,12 @@ import (
 	"net"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 )
 
 type TCPTProxy struct{}
 
-func NewTCPTProxy(hyClient *core.Client, listen string, timeout time.Duration,
+func NewTCPTProxy(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr),
 	errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*TCPTProxy, error) {
diff --git a/pkg/tproxy/udp_linux.go b/app/tproxy/udp_linux.go
similarity index 94%
rename from pkg/tproxy/udp_linux.go
rename to app/tproxy/udp_linux.go
index daa6f7f..b67500d 100644
--- a/pkg/tproxy/udp_linux.go
+++ b/app/tproxy/udp_linux.go
@@ -5,13 +5,13 @@ import (
 	"time"
 
 	"github.com/LiamHaworth/go-tproxy"
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 )
 
 const udpBufferSize = 4096
 
 type UDPTProxy struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	ListenAddr *net.UDPAddr
 	Timeout    time.Duration
 
@@ -19,7 +19,7 @@ type UDPTProxy struct {
 	ErrorFunc func(addr, reqAddr net.Addr, err error)
 }
 
-func NewUDPTProxy(hyClient *core.Client, listen string, timeout time.Duration,
+func NewUDPTProxy(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr),
 	errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*UDPTProxy, error) {
diff --git a/pkg/tproxy/udp_stub.go b/app/tproxy/udp_stub.go
similarity index 77%
rename from pkg/tproxy/udp_stub.go
rename to app/tproxy/udp_stub.go
index c884953..d794dfb 100644
--- a/pkg/tproxy/udp_stub.go
+++ b/app/tproxy/udp_stub.go
@@ -8,14 +8,14 @@ import (
 	"net"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 )
 
 var ErrTimeout = errors.New("inactivity timeout")
 
 type UDPTProxy struct{}
 
-func NewUDPTProxy(hyClient *core.Client, listen string, timeout time.Duration,
+func NewUDPTProxy(hyClient *cs.Client, listen string, timeout time.Duration,
 	connFunc func(addr, reqAddr net.Addr), errorFunc func(addr, reqAddr net.Addr, err error),
 ) (*UDPTProxy, error) {
 	return nil, errors.New("not supported on the current system")
diff --git a/pkg/tun/server.go b/app/tun/server.go
similarity index 93%
rename from pkg/tun/server.go
rename to app/tun/server.go
index 337713c..297257b 100644
--- a/pkg/tun/server.go
+++ b/app/tun/server.go
@@ -14,7 +14,7 @@ import (
 
 	"github.com/xjasonlyu/tun2socks/v2/core/option"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/sirupsen/logrus"
 	t2score "github.com/xjasonlyu/tun2socks/v2/core"
 	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
@@ -27,7 +27,7 @@ import (
 var _ adapter.TransportHandler = (*Server)(nil)
 
 type Server struct {
-	HyClient   *core.Client
+	HyClient   *cs.Client
 	Timeout    time.Duration
 	DeviceInfo DeviceInfo
 
@@ -66,7 +66,7 @@ func (d *DeviceInfo) Open() (dev device.Device, err error) {
 	return
 }
 
-func NewServerWithTunFd(hyClient *core.Client, timeout time.Duration, tunFd int, mtu uint32,
+func NewServerWithTunFd(hyClient *cs.Client, timeout time.Duration, tunFd int, mtu uint32,
 	tcpSendBufferSize, tcpReceiveBufferSize int, tcpModerateReceiveBuffer bool,
 ) (*Server, error) {
 	if mtu == 0 {
@@ -87,7 +87,7 @@ func NewServerWithTunFd(hyClient *core.Client, timeout time.Duration, tunFd int,
 	return s, nil
 }
 
-func NewServer(hyClient *core.Client, timeout time.Duration, name string, mtu uint32,
+func NewServer(hyClient *cs.Client, timeout time.Duration, name string, mtu uint32,
 	tcpSendBufferSize, tcpReceiveBufferSize int, tcpModerateReceiveBuffer bool,
 ) (*Server, error) {
 	if mtu == 0 {
diff --git a/pkg/tun/tcp.go b/app/tun/tcp.go
similarity index 95%
rename from pkg/tun/tcp.go
rename to app/tun/tcp.go
index 2b09ab8..7a59989 100644
--- a/pkg/tun/tcp.go
+++ b/app/tun/tcp.go
@@ -6,7 +6,7 @@ package tun
 import (
 	"net"
 
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/utils"
 	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 )
 
diff --git a/pkg/tun/udp.go b/app/tun/udp.go
similarity index 92%
rename from pkg/tun/udp.go
rename to app/tun/udp.go
index d81309a..78f3f31 100644
--- a/pkg/tun/udp.go
+++ b/app/tun/udp.go
@@ -9,7 +9,7 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/core"
+	"github.com/apernet/hysteria/core/cs"
 	"github.com/xjasonlyu/tun2socks/v2/core/adapter"
 )
 
@@ -52,7 +52,7 @@ func (s *Server) handleUDPConn(conn adapter.UDPConn) {
 	err = s.relayUDP(conn, rc, &remoteAddr, s.Timeout)
 }
 
-func (s *Server) relayUDP(lc adapter.UDPConn, rc core.HyUDPConn, to *net.UDPAddr, timeout time.Duration) (err error) {
+func (s *Server) relayUDP(lc adapter.UDPConn, rc cs.HyUDPConn, to *net.UDPAddr, timeout time.Duration) (err error) {
 	errChan := make(chan error, 2)
 	// local => remote
 	go func() {
diff --git a/build.ps1 b/build.ps1
index 462beb5..e97014c 100644
--- a/build.ps1
+++ b/build.ps1
@@ -59,7 +59,7 @@ foreach ($platform in $platforms) {
     if ($env:GOOS -eq "windows") {
         $output = "$output.exe"
     }
-    go build -o $output -tags=gpl -ldflags $ldflags -trimpath ./cmd/
+    go build -o $output -tags=gpl -ldflags $ldflags -trimpath ./app/cmd/
     if ($LastExitCode -ne 0) {
         Write-Host "Error: failed to build $env:GOOS/$env:GOARCH" -ForegroundColor Red
         exit 1
diff --git a/build.sh b/build.sh
index 1c36dcb..1a4f5fa 100755
--- a/build.sh
+++ b/build.sh
@@ -52,7 +52,7 @@ for platform in "${platforms[@]}"; do
     if [ $GOOS = "windows" ]; then
         output="$output.exe"
     fi
-    env GOOS=$GOOS GOARCH=$GOARCH CGO_ENABLED=0 go build -o $output -tags=gpl -ldflags "$ldflags" -trimpath ./cmd/
+    env GOOS=$GOOS GOARCH=$GOARCH CGO_ENABLED=0 go build -o $output -tags=gpl -ldflags "$ldflags" -trimpath ./app/cmd/
     if [ $? -ne 0 ]; then
         echo "Error: failed to build $GOOS/$GOARCH"
         exit 1
diff --git a/pkg/acl/engine.go b/core/acl/engine.go
similarity index 98%
rename from pkg/acl/engine.go
rename to core/acl/engine.go
index 95f2b3c..679c971 100644
--- a/pkg/acl/engine.go
+++ b/core/acl/engine.go
@@ -8,7 +8,7 @@ import (
 
 	lru "github.com/hashicorp/golang-lru/v2"
 
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/utils"
 	"github.com/oschwald/geoip2-golang"
 )
 
diff --git a/pkg/acl/engine_test.go b/core/acl/engine_test.go
similarity index 100%
rename from pkg/acl/engine_test.go
rename to core/acl/engine_test.go
diff --git a/pkg/acl/entry.go b/core/acl/entry.go
similarity index 100%
rename from pkg/acl/entry.go
rename to core/acl/entry.go
diff --git a/pkg/acl/entry_test.go b/core/acl/entry_test.go
similarity index 100%
rename from pkg/acl/entry_test.go
rename to core/acl/entry_test.go
diff --git a/pkg/congestion/brutal.go b/core/congestion/brutal.go
similarity index 100%
rename from pkg/congestion/brutal.go
rename to core/congestion/brutal.go
diff --git a/pkg/congestion/pacer.go b/core/congestion/pacer.go
similarity index 100%
rename from pkg/congestion/pacer.go
rename to core/congestion/pacer.go
diff --git a/pkg/core/client.go b/core/cs/client.go
similarity index 98%
rename from pkg/core/client.go
rename to core/cs/client.go
index f6dc0ca..971d312 100644
--- a/pkg/core/client.go
+++ b/core/cs/client.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"bytes"
@@ -12,12 +12,12 @@ import (
 	"sync"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns"
+	"github.com/apernet/hysteria/core/pktconns"
 
-	"github.com/apernet/hysteria/pkg/congestion"
+	"github.com/apernet/hysteria/core/congestion"
 
-	"github.com/apernet/hysteria/pkg/pmtud"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/pmtud"
+	"github.com/apernet/hysteria/core/utils"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/lunixbochs/struc"
 )
diff --git a/pkg/core/frag.go b/core/cs/frag.go
similarity index 99%
rename from pkg/core/frag.go
rename to core/cs/frag.go
index 7a38774..c9e491d 100644
--- a/pkg/core/frag.go
+++ b/core/cs/frag.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 func fragUDPMessage(m udpMessage, maxSize int) []udpMessage {
 	if m.Size() <= maxSize {
diff --git a/pkg/core/frag_test.go b/core/cs/frag_test.go
similarity index 99%
rename from pkg/core/frag_test.go
rename to core/cs/frag_test.go
index aa1c616..b0c27cb 100644
--- a/pkg/core/frag_test.go
+++ b/core/cs/frag_test.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"reflect"
diff --git a/pkg/core/protocol.go b/core/cs/protocol.go
similarity index 99%
rename from pkg/core/protocol.go
rename to core/cs/protocol.go
index 6359ff9..2c1cef9 100644
--- a/pkg/core/protocol.go
+++ b/core/cs/protocol.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"time"
diff --git a/pkg/core/server.go b/core/cs/server.go
similarity index 96%
rename from pkg/core/server.go
rename to core/cs/server.go
index 8b30952..230903d 100644
--- a/pkg/core/server.go
+++ b/core/cs/server.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"context"
@@ -7,11 +7,11 @@ import (
 	"fmt"
 	"net"
 
-	"github.com/apernet/hysteria/pkg/congestion"
+	"github.com/apernet/hysteria/core/congestion"
 
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/pmtud"
-	"github.com/apernet/hysteria/pkg/transport"
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/pmtud"
+	"github.com/apernet/hysteria/core/transport"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/lunixbochs/struc"
 	"github.com/prometheus/client_golang/prometheus"
diff --git a/pkg/core/server_client.go b/core/cs/server_client.go
similarity index 98%
rename from pkg/core/server_client.go
rename to core/cs/server_client.go
index 893c7aa..4d2c9f6 100644
--- a/pkg/core/server_client.go
+++ b/core/cs/server_client.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"bytes"
@@ -9,9 +9,9 @@ import (
 	"strconv"
 	"sync"
 
-	"github.com/apernet/hysteria/pkg/acl"
-	"github.com/apernet/hysteria/pkg/transport"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/acl"
+	"github.com/apernet/hysteria/core/transport"
+	"github.com/apernet/hysteria/core/utils"
 	"github.com/lucas-clemente/quic-go"
 	"github.com/lunixbochs/struc"
 	"github.com/prometheus/client_golang/prometheus"
diff --git a/pkg/core/stream.go b/core/cs/stream.go
similarity index 99%
rename from pkg/core/stream.go
rename to core/cs/stream.go
index 65259e4..8670470 100644
--- a/pkg/core/stream.go
+++ b/core/cs/stream.go
@@ -1,4 +1,4 @@
-package core
+package cs
 
 import (
 	"context"
diff --git a/pkg/pktconns/faketcp/LICENSE b/core/pktconns/faketcp/LICENSE
similarity index 100%
rename from pkg/pktconns/faketcp/LICENSE
rename to core/pktconns/faketcp/LICENSE
diff --git a/pkg/pktconns/faketcp/obfs.go b/core/pktconns/faketcp/obfs.go
similarity index 97%
rename from pkg/pktconns/faketcp/obfs.go
rename to core/pktconns/faketcp/obfs.go
index f8d89f9..ead2281 100644
--- a/pkg/pktconns/faketcp/obfs.go
+++ b/core/pktconns/faketcp/obfs.go
@@ -6,7 +6,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns/obfs"
+	"github.com/apernet/hysteria/core/pktconns/obfs"
 )
 
 const udpBufferSize = 4096
diff --git a/pkg/pktconns/faketcp/tcp_linux.go b/core/pktconns/faketcp/tcp_linux.go
similarity index 100%
rename from pkg/pktconns/faketcp/tcp_linux.go
rename to core/pktconns/faketcp/tcp_linux.go
diff --git a/pkg/pktconns/faketcp/tcp_stub.go b/core/pktconns/faketcp/tcp_stub.go
similarity index 100%
rename from pkg/pktconns/faketcp/tcp_stub.go
rename to core/pktconns/faketcp/tcp_stub.go
diff --git a/pkg/pktconns/faketcp/tcp_test.go b/core/pktconns/faketcp/tcp_test.go
similarity index 100%
rename from pkg/pktconns/faketcp/tcp_test.go
rename to core/pktconns/faketcp/tcp_test.go
diff --git a/pkg/pktconns/funcs.go b/core/pktconns/funcs.go
similarity index 96%
rename from pkg/pktconns/funcs.go
rename to core/pktconns/funcs.go
index 23427c4..b0675f1 100644
--- a/pkg/pktconns/funcs.go
+++ b/core/pktconns/funcs.go
@@ -5,10 +5,10 @@ import (
 	"strings"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns/faketcp"
-	"github.com/apernet/hysteria/pkg/pktconns/obfs"
-	"github.com/apernet/hysteria/pkg/pktconns/udp"
-	"github.com/apernet/hysteria/pkg/pktconns/wechat"
+	"github.com/apernet/hysteria/core/pktconns/faketcp"
+	"github.com/apernet/hysteria/core/pktconns/obfs"
+	"github.com/apernet/hysteria/core/pktconns/udp"
+	"github.com/apernet/hysteria/core/pktconns/wechat"
 )
 
 type (
diff --git a/pkg/pktconns/obfs/obfs.go b/core/pktconns/obfs/obfs.go
similarity index 100%
rename from pkg/pktconns/obfs/obfs.go
rename to core/pktconns/obfs/obfs.go
diff --git a/pkg/pktconns/obfs/obfs_test.go b/core/pktconns/obfs/obfs_test.go
similarity index 100%
rename from pkg/pktconns/obfs/obfs_test.go
rename to core/pktconns/obfs/obfs_test.go
diff --git a/pkg/pktconns/udp/hop.go b/core/pktconns/udp/hop.go
similarity index 99%
rename from pkg/pktconns/udp/hop.go
rename to core/pktconns/udp/hop.go
index e1e4f9e..4458131 100644
--- a/pkg/pktconns/udp/hop.go
+++ b/core/pktconns/udp/hop.go
@@ -10,7 +10,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns/obfs"
+	"github.com/apernet/hysteria/core/pktconns/obfs"
 )
 
 const (
diff --git a/pkg/pktconns/udp/hop_test.go b/core/pktconns/udp/hop_test.go
similarity index 100%
rename from pkg/pktconns/udp/hop_test.go
rename to core/pktconns/udp/hop_test.go
diff --git a/pkg/pktconns/udp/obfs.go b/core/pktconns/udp/obfs.go
similarity index 97%
rename from pkg/pktconns/udp/obfs.go
rename to core/pktconns/udp/obfs.go
index 7aee8a9..9f1165e 100644
--- a/pkg/pktconns/udp/obfs.go
+++ b/core/pktconns/udp/obfs.go
@@ -7,7 +7,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns/obfs"
+	"github.com/apernet/hysteria/core/pktconns/obfs"
 )
 
 const udpBufferSize = 4096
diff --git a/pkg/pktconns/wechat/obfs.go b/core/pktconns/wechat/obfs.go
similarity index 98%
rename from pkg/pktconns/wechat/obfs.go
rename to core/pktconns/wechat/obfs.go
index 62a4d6b..e6935f7 100644
--- a/pkg/pktconns/wechat/obfs.go
+++ b/core/pktconns/wechat/obfs.go
@@ -9,7 +9,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/pktconns/obfs"
+	"github.com/apernet/hysteria/core/pktconns/obfs"
 )
 
 const udpBufferSize = 4096
diff --git a/pkg/pmtud/avail.go b/core/pmtud/avail.go
similarity index 100%
rename from pkg/pmtud/avail.go
rename to core/pmtud/avail.go
diff --git a/pkg/pmtud/unavail.go b/core/pmtud/unavail.go
similarity index 100%
rename from pkg/pmtud/unavail.go
rename to core/pmtud/unavail.go
diff --git a/pkg/sockopt/sockopt.go b/core/sockopt/sockopt.go
similarity index 100%
rename from pkg/sockopt/sockopt.go
rename to core/sockopt/sockopt.go
diff --git a/pkg/sockopt/sockopt_linux.go b/core/sockopt/sockopt_linux.go
similarity index 100%
rename from pkg/sockopt/sockopt_linux.go
rename to core/sockopt/sockopt_linux.go
diff --git a/pkg/sockopt/sockopt_others.go b/core/sockopt/sockopt_others.go
similarity index 100%
rename from pkg/sockopt/sockopt_others.go
rename to core/sockopt/sockopt_others.go
diff --git a/pkg/transport/client.go b/core/transport/client.go
similarity index 100%
rename from pkg/transport/client.go
rename to core/transport/client.go
diff --git a/pkg/transport/resolve.go b/core/transport/resolve.go
similarity index 100%
rename from pkg/transport/resolve.go
rename to core/transport/resolve.go
diff --git a/pkg/transport/server.go b/core/transport/server.go
similarity index 96%
rename from pkg/transport/server.go
rename to core/transport/server.go
index b32f7e9..dee4af2 100644
--- a/pkg/transport/server.go
+++ b/core/transport/server.go
@@ -5,8 +5,8 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/apernet/hysteria/pkg/sockopt"
-	"github.com/apernet/hysteria/pkg/utils"
+	"github.com/apernet/hysteria/core/sockopt"
+	"github.com/apernet/hysteria/core/utils"
 )
 
 type ServerTransport struct {
diff --git a/pkg/transport/socks5.go b/core/transport/socks5.go
similarity index 100%
rename from pkg/transport/socks5.go
rename to core/transport/socks5.go
diff --git a/pkg/utils/misc.go b/core/utils/misc.go
similarity index 100%
rename from pkg/utils/misc.go
rename to core/utils/misc.go
diff --git a/pkg/utils/pipe.go b/core/utils/pipe.go
similarity index 100%
rename from pkg/utils/pipe.go
rename to core/utils/pipe.go