func main() {
configText, err := ioutil.ReadFile("config.yml")
fatalIfErr(err)
var C Config
fatalIfErr(yaml.Unmarshal(configText, &C))
server := &Server{
sessionInfo: make(map[string]sessionInfo),
}
server.sshConfig = &ssh.ServerConfig{
KeyboardInteractiveCallback: server.KeyboardInteractiveCallback,
PublicKeyCallback: server.PublicKeyCallback,
}
pemBytes, err := ioutil.ReadFile(C.HostKey)
fatalIfErr(err)
private, err := ssh.ParsePrivateKey([]byte(pemBytes))
fatalIfErr(err)
server.sshConfig.AddHostKey(private)
listener, err := net.Listen("tcp", C.Listen)
fatalIfErr(err)
for {
conn, err := listener.Accept()
if err != nil {
log.Println("Accept failed:", err)
continue
}
go server.Handle(conn)
}
}
func ExampleNewServerConn() {
// An SSH server is represented by a ServerConfig, which holds
// certificate details and handles authentication of ServerConns.
config := &ssh.ServerConfig{
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())
},
}
privateBytes, err := ioutil.ReadFile("id_rsa")
if err != nil {
panic("Failed to load private key")
}
private, err := ssh.ParsePrivateKey(privateBytes)
if err != nil {
panic("Failed to parse private key")
}
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 {
panic("failed to listen for connection")
}
nConn, err := listener.Accept()
if err != nil {
panic("failed to accept incoming connection")
}
// Before use, a handshake must be performed on the incoming
// net.Conn.
_, chans, reqs, err := ssh.NewServerConn(nConn, config)
if err != nil {
panic("failed to handshake")
}
// 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 {
panic("could not accept channel.")
}
// 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 {
ok := false
switch req.Type {
case "shell":
ok = true
if len(req.Payload) > 0 {
// We don't accept any
// commands, only the
// default shell.
ok = false
}
}
req.Reply(ok, nil)
}
}(requests)
term := terminal.NewTerminal(channel, "> ")
go func() {
defer channel.Close()
for {
line, err := term.ReadLine()
if err != nil {
break
}
fmt.Println(line)
}
}()
}
}