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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ssh_test
import (
"bufio"
"bytes"
"fmt"
"io/ioutil"
"log"
"net"
"net/http"
"os"
"path/filepath"
"strings"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/terminal"
)
func ExampleNewServerConn() {
// Public key authentication is done by comparing
// the public key of a received connection
// with the entries in the authorized_keys file.
authorizedKeysBytes, err := ioutil.ReadFile("authorized_keys")
if err != nil {
log.Fatalf("Failed to load authorized_keys, err: %v", err)
}
authorizedKeysMap := map[string]bool{}
for len(authorizedKeysBytes) > 0 {
pubKey, _, _, rest, err := ssh.ParseAuthorizedKey(authorizedKeysBytes)
if err != nil {
log.Fatal(err)
}
authorizedKeysMap[string(pubKey.Marshal())] = true
authorizedKeysBytes = rest
}
// An SSH server is represented by a ServerConfig, which holds
// certificate details and handles authentication of ServerConns.
config := &ssh.ServerConfig{
// Remove to disable password auth.
PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
// Should use constant-time compare (or better, salt+hash) in
// a production setting.
if c.User() == "testuser" && string(pass) == "tiger" {
return nil, nil
}
return nil, fmt.Errorf("password rejected for %q", c.User())
},
// Remove to disable public key auth.
PublicKeyCallback: func(c ssh.ConnMetadata, pubKey ssh.PublicKey) (*ssh.Permissions, error) {
if authorizedKeysMap[string(pubKey.Marshal())] {
return &ssh.Permissions{
// Record the public key used for authentication.
Extensions: map[string]string{
"pubkey-fp": ssh.FingerprintSHA256(pubKey),
},
}, nil
}
return nil, fmt.Errorf("unknown public key for %q", c.User())
},
}
privateBytes, err := ioutil.ReadFile("id_rsa")
if err != nil {
log.Fatal("Failed to load private key: ", err)
}
private, err := ssh.ParsePrivateKey(privateBytes)
if err != nil {
log.Fatal("Failed to parse private key: ", err)
}
config.AddHostKey(private)
// Once a ServerConfig has been configured, connections can be
// accepted.
listener, err := net.Listen("tcp", "0.0.0.0:2022")
if err != nil {
log.Fatal("failed to listen for connection: ", err)
}
nConn, err := listener.Accept()
if err != nil {
log.Fatal("failed to accept incoming connection: ", err)
}
// Before use, a handshake must be performed on the incoming
// net.Conn.
conn, chans, reqs, err := ssh.NewServerConn(nConn, config)
if err != nil {
log.Fatal("failed to handshake: ", err)
}
log.Printf("logged in with key %s", conn.Permissions.Extensions["pubkey-fp"])
// The incoming Request channel must be serviced.
go ssh.DiscardRequests(reqs)
// Service the incoming Channel channel.
for newChannel := range chans {
// Channels have a type, depending on the application level
// protocol intended. In the case of a shell, the type is
// "session" and ServerShell may be used to present a simple
// terminal interface.
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
continue
}
channel, requests, err := newChannel.Accept()
if err != nil {
log.Fatalf("Could not accept channel: %v", err)
}
// Sessions have out-of-band requests such as "shell",
// "pty-req" and "env". Here we handle only the
// "shell" request.
go func(in <-chan *ssh.Request) {
for req := range in {
req.Reply(req.Type == "shell", nil)
}
}(requests)
term := terminal.NewTerminal(channel, "> ")
go func() {
defer channel.Close()
for {
line, err := term.ReadLine()
if err != nil {
break
}
fmt.Println(line)
}
}()
}
}
func ExampleHostKeyCheck() {
// Every client must provide a host key check. Here is a
// simple-minded parse of OpenSSH's known_hosts file
host := "hostname"
file, err := os.Open(filepath.Join(os.Getenv("HOME"), ".ssh", "known_hosts"))
if err != nil {
log.Fatal(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 {
log.Fatalf("error parsing %q: %v", fields[2], err)
}
break
}
}
if hostKey == nil {
log.Fatalf("no hostkey for %s", host)
}
config := ssh.ClientConfig{
User: os.Getenv("USER"),
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
_, err = ssh.Dial("tcp", host+":22", &config)
log.Println(err)
}
func ExampleDial() {
var hostKey ssh.PublicKey
// An SSH client is represented with a ClientConn.
//
// To authenticate with the remote server you must pass at least one
// implementation of AuthMethod via the Auth field in ClientConfig,
// and provide a HostKeyCallback.
config := &ssh.ClientConfig{
User: "username",
Auth: []ssh.AuthMethod{
ssh.Password("yourpassword"),
},
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
client, err := ssh.Dial("tcp", "yourserver.com:22", 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("/usr/bin/whoami"); err != nil {
log.Fatal("Failed to run: " + err.Error())
}
fmt.Println(b.String())
}
func ExamplePublicKeys() {
var hostKey ssh.PublicKey
// A public key may be used to authenticate against the remote
// server by using an unencrypted PEM-encoded private key file.
//
// If you have an encrypted private key, the crypto/x509 package
// can be used to decrypt it.
key, err := ioutil.ReadFile("/home/user/.ssh/id_rsa")
if err != nil {
log.Fatalf("unable to read private key: %v", err)
}
// Create the Signer for this private key.
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{
// Use the PublicKeys method for remote authentication.
ssh.PublicKeys(signer),
},
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
// Connect to the remote server and perform the SSH handshake.
client, err := ssh.Dial("tcp", "host.com:22", config)
if err != nil {
log.Fatalf("unable to connect: %v", err)
}
defer client.Close()
}
func ExampleClient_Listen() {
var hostKey ssh.PublicKey
config := &ssh.ClientConfig{
User: "username",
Auth: []ssh.AuthMethod{
ssh.Password("password"),
},
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
// Dial your ssh server.
conn, err := ssh.Dial("tcp", "localhost:22", config)
if err != nil {
log.Fatal("unable to connect: ", err)
}
defer conn.Close()
// Request the remote side to open port 8080 on all interfaces.
l, err := conn.Listen("tcp", "0.0.0.0:8080")
if err != nil {
log.Fatal("unable to register tcp forward: ", err)
}
defer l.Close()
// Serve HTTP with your SSH server acting as a reverse proxy.
http.Serve(l, http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
fmt.Fprintf(resp, "Hello world!\n")
}))
}
func ExampleSession_RequestPty() {
var hostKey ssh.PublicKey
// Create client config
config := &ssh.ClientConfig{
User: "username",
Auth: []ssh.AuthMethod{
ssh.Password("password"),
},
HostKeyCallback: ssh.FixedHostKey(hostKey),
}
// Connect to ssh server
conn, err := ssh.Dial("tcp", "localhost:22", config)
if err != nil {
log.Fatal("unable to connect: ", err)
}
defer conn.Close()
// Create a session
session, err := conn.NewSession()
if err != nil {
log.Fatal("unable to create session: ", err)
}
defer session.Close()
// Set up terminal modes
modes := ssh.TerminalModes{
ssh.ECHO: 0, // disable echoing
ssh.TTY_OP_ISPEED: 14400, // input speed = 14.4kbaud
ssh.TTY_OP_OSPEED: 14400, // output speed = 14.4kbaud
}
// Request pseudo terminal
if err := session.RequestPty("xterm", 40, 80, modes); err != nil {
log.Fatal("request for pseudo terminal failed: ", err)
}
// Start remote shell
if err := session.Shell(); err != nil {
log.Fatal("failed to start shell: ", err)
}
}