diff --git a/_chapter14/section55/main.go b/_chapter14/section55/main.go
index 830f360..5ff6eac 100644
--- a/_chapter14/section55/main.go
+++ b/_chapter14/section55/main.go
@@ -1,4 +1,4 @@
-package main
+package section55
 
 import (
 	"context"
diff --git a/_chapter14/section55/main_test.go b/_chapter14/section55/main_test.go
index aa6a56b..1ff19ff 100644
--- a/_chapter14/section55/main_test.go
+++ b/_chapter14/section55/main_test.go
@@ -1,4 +1,4 @@
-package main
+package section55
 
 import (
 	"context"
diff --git a/_chapter14/section56/main.go b/_chapter14/section56/main.go
new file mode 100644
index 0000000..dd0c05f
--- /dev/null
+++ b/_chapter14/section56/main.go
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"golang.org/x/sync/errgroup"
+	"log"
+	"net"
+	"net/http"
+	"os"
+)
+
+func run(ctx context.Context, l net.Listener) error {
+	s := &http.Server{
+		// 인수로 받은 net.Listener를 이용하므로 Addr 필드는 지정하지 않습니다.
+		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			fmt.Fprintf(w, "Hello, %s!", r.URL.Path[1:])
+		}),
+	}
+	eg, ctx := errgroup.WithContext(ctx)
+	eg.Go(func() error {
+		// Serve 메서드로 변경합니다.
+		if err := s.Serve(l); err != nil &&
+			err != http.ErrServerClosed {
+			log.Printf("failed to close: %+v", err)
+			return err
+		}
+		return nil
+	})
+
+	<-ctx.Done()
+	if err := s.Shutdown(context.Background()); err != nil {
+		log.Printf("failed to shutdown: %+v", err)
+	}
+
+	return eg.Wait()
+}
+
+func main() {
+	// go run . 18080
+	if len(os.Args) != 2 {
+		log.Printf("need port number\n")
+		os.Exit(1)
+	}
+
+	p := os.Args[1]
+	l, err := net.Listen("tcp", ":"+p)
+	if err != nil {
+		log.Fatalf("failed to listen port %s: %v", p, err)
+	}
+
+	if err := run(context.Background(), l); err != nil {
+		log.Printf("failed to terminate server: %v", err)
+		os.Exit(1)
+	}
+}
diff --git a/_chapter14/section56/main_test.go b/_chapter14/section56/main_test.go
new file mode 100644
index 0000000..cdd6cb4
--- /dev/null
+++ b/_chapter14/section56/main_test.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"golang.org/x/sync/errgroup"
+	"io"
+	"net"
+	"net/http"
+	"testing"
+)
+
+func TestRun(t *testing.T) {
+	// net/http 에서는 포트 번호에 0을 지정하면 사용 가능한 포트 번호를 동적으로 선택합니다.
+	l, err := net.Listen("tcp", "localhost:0")
+	if err != nil {
+		t.Fatalf("failed to listen port %v", err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	eg, ctx := errgroup.WithContext(ctx)
+	eg.Go(func() error {
+		return run(ctx, l)
+	})
+
+	in := "message"
+	url := fmt.Sprintf("http://%s/%s", l.Addr().String(), in)
+	// 어떤 포트 번호로 리슨중인지 확인합니다.
+	t.Logf("try request to %q", url)
+	rsp, err := http.Get(url)
+
+	// 이후 코드 동일
+	if err != nil {
+		t.Errorf("failed to get: %+v", err)
+	}
+	defer rsp.Body.Close()
+
+	got, err := io.ReadAll(rsp.Body)
+	if err != nil {
+		t.Fatalf("failed to read body: %v", err)
+	}
+
+	// HTTP 서버의 반환값을 검증합니다.
+	want := fmt.Sprintf("Hello, %s!", in)
+	if string(got) != want {
+		t.Errorf("want %q, but got %q", want, got)
+	}
+
+	// run 함수를 종료합니다.
+	cancel()
+	if err := eg.Wait(); err != nil {
+		t.Fatal(err)
+	}
+}