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pbproxy.go
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pbproxy.go
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package main
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha1"
"flag"
//"fmt"
"io"
"io/ioutil"
"net"
"os"
"golang.org/x/crypto/pbkdf2"
)
//crypto code
func getkey(pwd string) []byte {
salt := []byte("1221")
key := pbkdf2.Key([]byte(pwd), salt, 4096, 32, sha1.New)
return key
}
func decrypt(pwd string, ciphert string) []byte {
key := getkey(pwd)
fulltext := []byte(ciphert)
nonce := fulltext[:12]
ciphertext := fulltext[12:]
block, err := aes.NewCipher(key)
if err != nil {
panic(err.Error())
}
//automatically 32 byte key will select aesgcm-256
aesgcm, err := cipher.NewGCM(block)
if err != nil {
panic(err.Error())
}
plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
panic(err.Error())
}
return plaintext
}
func encrypt(pwd string, plain string) []byte {
key := getkey(pwd)
plaintext := []byte(plain)
block, err := aes.NewCipher(key)
if err != nil {
panic(err.Error())
}
nonce := make([]byte, 12)
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
panic(err.Error())
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
panic(err.Error())
}
ciphertext := aesgcm.Seal(nil, nonce, plaintext, nil)
ciphertext = append(nonce, ciphertext...)
return ciphertext
}
//crypto code
func sshdtopbproxyc(conn net.Conn, connsshd net.Conn, pwdFile string) {
//getting data from sshd server
for {
buf := make([]byte, 3000)
data, err := connsshd.Read(buf)
buf = buf[:data]
//fmt.Println(string(buf))
if err != nil {
connsshd.Close()
break
}
if data != 0 {
//conn.Write(buf)
conn.Write(encrypt(pwdFile, string(buf)))
}
}
}
func stdin_server(conn net.Conn, connsshd net.Conn, pwdFile string) {
//reader logic
//bufio.NewReader(os.Stdin)
for {
buf := make([]byte, 3000)
data, err := os.Stdin.Read(buf)
//buf = bytes.Trim(buf, "\x00")
buf = buf[:data]
if err != nil {
break
}
if data != 0 {
conn.Write(encrypt(pwdFile, string(buf)))
}
}
}
func stdout_client(conn net.Conn, pwdfile string) {
for {
buf := make([]byte, 3000)
data, err := conn.Read(buf)
//buf = bytes.Trim(buf, "\x00")
buf = buf[:data]
if err != nil {
conn.Close()
break
}
if data != 0 {
os.Stdout.Write(decrypt(pwdfile, string(buf)))
}
}
}
func Execute_Client(dstIp string, dstPort string, pwdFile string) {
conn, err := net.Dial("tcp", dstIp+":"+dstPort)
if err != nil {
os.Exit(1)
}
//write to server
go stdout_client(conn, pwdFile)
//reader logic
for {
buf := make([]byte, 3000)
data, err := os.Stdin.Read(buf)
buf = buf[:data]
if err != nil {
//fmt.Println(err)
conn.Close()
break
}
if data != 0 {
conn.Write(encrypt(pwdFile, string(buf)))
}
}
}
func handleConnections(conn net.Conn, dstIp string, dstPort string, pwdFile string) {
//connect to ssd here...
connsshd, err := net.Dial("tcp", dstIp+":"+dstPort)
if err != nil {
//fmt.Println(err)
os.Exit(1)
}
defer connsshd.Close()
defer conn.Close()
//go routine for sshd to pbproxyc
go sshdtopbproxyc(conn, connsshd, pwdFile)
//go routine
go stdin_server(conn, connsshd, pwdFile)
//read from client
for {
buf := make([]byte, 3000)
data, err := conn.Read(buf)
buf = buf[:data]
if err != nil {
conn.Close()
break
}
if data != 0 {
//send to sshd...
//decrypt and send
connsshd.Write(decrypt(pwdFile, string(buf)))
}
}
}
func Execute_Server(dstIp string, dstPort string, pwdFile string, listenPort string) {
ln, err := net.Listen("tcp", ":"+listenPort)
if err != nil {
os.Exit(1)
}
for {
conn, err := ln.Accept()
if err != nil {
os.Exit(1)
}
go handleConnections(conn, dstIp, dstPort, pwdFile)
}
}
//main function
func main() {
var pwdfileI string
var listenPortI string
var dstIp string
var dstPort string
// flags declaration using flag package
flag.StringVar(&pwdfileI, "p", "None", "Provide the file")
flag.StringVar(&listenPortI, "l", "None", "Provide the file")
flag.Parse()
//read pwdfile
password, _ := ioutil.ReadFile(pwdfileI)
//test
//fmt.Println(string(encrypt(string(password), "shashank")))
//fmt.Println(string(decrypt(string(password), string(encrypt(string(password), "shashankken")))))
if listenPortI == "None" {
if len(os.Args) == 5 {
dstIp = os.Args[len(os.Args)-2]
dstPort = os.Args[len(os.Args)-1]
} else {
//fmt.Println("Issue with input arguments")
os.Exit(1)
}
Execute_Client(dstIp, dstPort, string(password))
} else {
if len(os.Args) == 7 {
dstIp = os.Args[len(os.Args)-2]
dstPort = os.Args[len(os.Args)-1]
} else {
//fmt.Println("Issue with input arguments")
os.Exit(1)
}
Execute_Server(dstIp, dstPort, string(password), listenPortI)
}
}