How to add custom listener for ipv4

[aaronwood]

Hi All,

How do you start echo, and make it listen on ipv4? When I start it on my linux VM it only listens on ipv6. I see that there is a way to customize echo for a listener as follows, but I get a "main.go:45:12: undefined: net" error.

l, err := net.Listen("tcp", ":1323")
if err != nil {
e.Logger.Fatal(err)
}
e.Listener = l

Thanks for any help.

[aldas]

package main

import (
	"errors"
	"github.com/labstack/echo/v4"
	"net"
	"net/http"
)

func main() {
	e := echo.New()
	e.GET("/", func(c echo.Context) error {
		return c.String(http.StatusOK, "Hi")
	})

	l, err := net.Listen("tcp4", ":1323")
	if err != nil {
		e.Logger.Fatal(err)
	}
	s := http.Server{
		Handler: e,
	}
	if err := s.Serve(l); err != nil && !errors.Is(err, http.ErrServerClosed) {
		e.Logger.Fatal(err)
	}
}

Other suitable "network" values can be seen here https://github.com/golang/go/blob/071aed2aaa0ed819582c5bff44b70d43c61f504a/src/net/dial.go#L231-L238

[digitalchild]

How would you do this AutoTLS cookbook? or even StartTLS ?

[aldas]

I have not tried but this should work:

replace

	s := http.Server{
		Handler: e,
	}

with

	autoTLSManager := autocert.Manager{
		Prompt: autocert.AcceptTOS,
		// Cache certificates to avoid issues with rate limits (https://letsencrypt.org/docs/rate-limits)
		Cache: autocert.DirCache("/var/www/.cache"),
		//HostPolicy: autocert.HostWhitelist("<DOMAIN>"),
	}
	s := http.Server{
		Handler: e, // set Echo as handler
		TLSConfig: &tls.Config{
			//Certificates: nil, // <-- s.ListenAndServeTLS will populate this field
			GetCertificate: autoTLSManager.GetCertificate,
			NextProtos:     []string{acme.ALPNProto},
		},
		//ReadTimeout: 30 * time.Second, // use custom timeouts
	}

so it should look like

package main

import (
	"crypto/tls"
	"errors"
	"github.com/labstack/echo/v4"
	"golang.org/x/crypto/acme"
	"golang.org/x/crypto/acme/autocert"
	"net"
	"net/http"
)

func main() {
	e := echo.New()
	e.GET("/", func(c echo.Context) error {
		return c.String(http.StatusOK, "Hi")
	})

	l, err := net.Listen("tcp4", ":443") 
	if err != nil {
		e.Logger.Fatal(err)
	}
	defer l.Close()

	autoTLSManager := autocert.Manager{
		Prompt: autocert.AcceptTOS,
		// Cache certificates to avoid issues with rate limits (https://letsencrypt.org/docs/rate-limits)
		Cache: autocert.DirCache("/var/www/.cache"),
		//HostPolicy: autocert.HostWhitelist("<DOMAIN>"),
	}
	s := http.Server{
		Handler: e, // set Echo as handler
		TLSConfig: &tls.Config{
			//Certificates: nil, // <-- s.ListenAndServeTLS will populate this field
			GetCertificate: autoTLSManager.GetCertificate,
			NextProtos:     []string{acme.ALPNProto},
		},
		//ReadTimeout: 30 * time.Second, // use custom timeouts
	}

	if err := s.ServeTLS(l, "", ""); err != nil && !errors.Is(err, http.ErrServerClosed) {
		e.Logger.Fatal(err)
	}
}

[digitalchild]

Thanks, that got the server running on tcp4 however now the acme/autocert just says no viable challenge. I believe this is a DNS issue, but cannot figure it out.

Any suggestions? This server is also running nginx would that interfere at all?

[aldas]

I do not think using ipv4 should be problem with TLS. I personally do not have any experience with Go autotls. I always use Nginx and certbot (https://certbot.eff.org/) cronjob to renew certificates. I even offload SSL at Nginx and serve Go application on plain http internally.

[digitalchild]

Thanks, I ended up getting around the issue by generating self-signed certs and using Cloudflare SSL on a proxied subdomain using a supported port.