Go SSH Client

Go proof of concept ssh client, using ssh keys, ignoring host key verification. Note, code is here for host key verification, if you want it.

package main

// Ref: https://github.com/golang/crypto/blob/master/ssh/example_test.go
// go get -u golang.org/x/crypto/ssh
import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"golang.org/x/crypto/ssh"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"
)

func getHostKey(host string) (ssh.PublicKey, error) {
	file, err := os.Open(filepath.Join(os.Getenv("HOME"), ".ssh", "known_hosts"))
	if err != nil {
		return nil, err
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	var hostKey ssh.PublicKey
	for scanner.Scan() {
		fields := strings.Split(scanner.Text(), " ")
		if len(fields) != 3 {
			continue
		}
		if strings.Contains(fields[0], host) {
			var err error
			hostKey, _, _, _, err = ssh.ParseAuthorizedKey(scanner.Bytes())
			if err != nil {
				return nil, errors.New(fmt.Sprintf("error parsing %q: %v", fields[2], err))
			}
			break
		}
	}

	if hostKey == nil {
		return nil, errors.New(fmt.Sprintf("no hostkey for %s", host))
	}
	return hostKey, nil
}

func main() {

	user := "sparky"
	server := "45.25.125.83:22"
	command := "uptime"

	// If you want to valid keys ...
	// hostKey, err := getHostKey("smtp.aipiggybot.io")
	//if err != nil {
	//	log.Fatal(err)
	//}

	var hostKey ssh.PublicKey

	key, err := ioutil.ReadFile(filepath.Join(os.Getenv("HOME"), ".ssh", "id_rsa"))
	if err != nil {
		log.Fatalf("Unable to read private key: %v", err)
	}

	signer, err := ssh.ParsePrivateKey(key)
	if err != nil {
		log.Fatalf("Unable to parse private key: %v", err)
	}

	config := &ssh.ClientConfig{
		User: user,
		Auth: []ssh.AuthMethod{
			ssh.PublicKeys(signer),
			// ssh.Password("yourpassword"),
		},
		HostKeyCallback: ssh.FixedHostKey(hostKey),
	}

	// Ignore key validation
	config.HostKeyCallback = ssh.InsecureIgnoreHostKey()

	client, err := ssh.Dial("tcp", server, config)
	if err != nil {
		log.Fatal("Failed to dial: ", err)
	}

	// Each ClientConn can support multiple interactive sessions,
	// represented by a Session.
	session, err := client.NewSession()
	if err != nil {
		log.Fatal("Failed to create session: ", err)
	}
	defer session.Close()

	// Once a Session is created, you can execute a single command on
	// the remote side using the Run method.
	var b bytes.Buffer
	session.Stdout = &b
	if err := session.Run(command); err != nil {
		log.Fatal("Failed to run: " + err.Error())
	}
	fmt.Println(b.String())
}