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agent now uses a fixed host key using the go embed package.

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Printing welcome message when user logs in.
This commit is contained in:
Erik Brakkee 2024-07-21 11:22:05 +02:00
parent 8981efd0b5
commit c25129a9bf
2 changed files with 49 additions and 34 deletions
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48
cmd/agent/agent.go
View File

@ -4,10 +4,6 @@ import (
"bufio" "bufio"
"cidebug/pkg/iowrappers" "cidebug/pkg/iowrappers"
"cidebug/pkg/websocketutil" "cidebug/pkg/websocketutil"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"fmt" "fmt"
"github.com/gorilla/websocket" "github.com/gorilla/websocket"
"io" "io"
@ -22,8 +18,13 @@ import (
"github.com/gliderlabs/ssh" "github.com/gliderlabs/ssh"
"github.com/hashicorp/yamux" "github.com/hashicorp/yamux"
"github.com/pkg/sftp" "github.com/pkg/sftp"
_ "embed"
) )
//go:embed hostkey.pem
var hostPrivateKey []byte
func SftpHandler(sess ssh.Session) { func SftpHandler(sess ssh.Session) {
debugStream := io.Discard debugStream := io.Discard
serverOptions := []sftp.ServerOption{ serverOptions := []sftp.ServerOption{
@ -57,6 +58,8 @@ func setWinsize(f *os.File, w, h int) {
func sshServer(hostKeyFile string) *ssh.Server { func sshServer(hostKeyFile string) *ssh.Server {
ssh.Handle(func(s ssh.Session) { ssh.Handle(func(s ssh.Session) {
hostname, _ := os.Hostname()
io.WriteString(s, fmt.Sprintf("Your are now on %s\n\n", hostname))
cmd := exec.Command("bash") cmd := exec.Command("bash")
ptyReq, winCh, isPty := s.Pty() ptyReq, winCh, isPty := s.Pty()
if isPty { if isPty {
@ -88,11 +91,13 @@ func sshServer(hostKeyFile string) *ssh.Server {
"sftp": SftpHandler, "sftp": SftpHandler,
}, },
} }
err := generateHostKey(hostKeyFile, 2048) //err := generateHostKey(hostKeyFile, 2048)
if err != nil { //if err != nil {
log.Printf("Could not create host key file '%s': %v", hostKeyFile, err) // log.Printf("Could not create host key file '%s': %v", hostKeyFile, err)
} //}
option := ssh.HostKeyFile(hostKeyFile) //option := ssh.HostKeyFile(hostKeyFile)
option := ssh.HostKeyPEM(hostPrivateKey)
option(&server) option(&server)
return &server return &server
@ -138,31 +143,6 @@ func (f ReaderFunc) Read(p []byte) (n int, err error) {
return f(p) return f(p)
} }
func generateHostKey(filename string, bitSize int) error {
if _, err := os.Stat(filename); !os.IsNotExist(err) {
log.Printf("Reusing key file '%s'", filename)
return nil
}
privateKey, err := rsa.GenerateKey(rand.Reader, bitSize)
if err != nil {
return err
}
privateKeyPEM := &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
}
privateKeyFile, err := os.Create(filename)
if err != nil {
return err
}
defer privateKeyFile.Close()
log.Printf("Generating key '%s'", filename)
return pem.Encode(privateKeyFile, privateKeyPEM)
}
func main() { func main() {
wsURL := os.Args[1] wsURL := os.Args[1]
conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil) conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)

35
pkg/sshutils/ssh.go Normal file
View File

@ -0,0 +1,35 @@
package sshutils
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"log"
"os"
)
func generateHostKey(filename string, bitSize int) error {
if _, err := os.Stat(filename); !os.IsNotExist(err) {
log.Printf("Reusing key file '%s'", filename)
return nil
}
privateKey, err := rsa.GenerateKey(rand.Reader, bitSize)
if err != nil {
return err
}
privateKeyPEM := &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
}
privateKeyFile, err := os.Create(filename)
if err != nil {
return err
}
defer privateKeyFile.Close()
log.Printf("Generating key '%s'", filename)
return pem.Encode(privateKeyFile, privateKeyPEM)
}