https server use tls1.2

main.go

package main

import (
	// "fmt"
	// "io"
	"crypto/tls"
	"log"
	"net/http"
	"time"
)

func HelloServer(w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "text/plain")
	w.Write([]byte("This is an example server.\n"))
}

func main() {
	s := &http.Server{
		Addr: ":44335",
		TLSConfig: &tls.Config{
			PreferServerCipherSuites: true,
			CurvePreferences: []tls.CurveID{
				tls.CurveP256,
				tls.X25519,
			},
			MinVersion: tls.VersionTLS12,
			MaxVersion: tls.VersionTLS12,
		},
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 5 * time.Second,
		IdleTimeout:  5 * time.Second,
	}
	http.HandleFunc("/hello", HelloServer)
	err := s.ListenAndServeTLS("server.crt", "server.key")
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}