License and readme

.gitignore

@@ -0,0 +1 @@
+data/

Dockerfile

@@ -12,4 +12,12 @@ WORKDIR /app
 
 COPY --from=builder /app/ssh-honeypot .
 
+RUN mkdir data
+
+ENV PATH data/ssh-honeypot.log
+ENV PORT 22
+
+EXPOSE 22
+VOLUME /app/data
+
 ENTRYPOINT ["./ssh-honeypot"]

LICENSE.md

@@ -0,0 +1,7 @@
+Copyright © 2023 Brieuc Dubois
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -0,0 +1,13 @@
+# SSH-Honeypot
+
+## Overview
+SSH-Honeypot is a simple, effective server designed to log SSH connection attempts. It's built using Go and can be easily deployed using Docker.
+
+The server start a ssh server on port 22 and log any connection attempt to a logfile.
+
+## KISS Principles
+This project adheres to the [KISS principles](https://en.wikipedia.org/wiki/KISS_principle), utilizing minimalistic and efficient codebase that focus on its core functionality. This approach avoids unnecessary complexities, ensuring the project is easy to maintain and deploy across various architectures.
+
+
+## License
+This project is licensed under the [MIT license](LICENSE.md).

docker-compose.yaml

@@ -2,4 +2,6 @@ services:
   ssh-honeypot:
     build: .
     ports:
-      - "2222:22"
+    - "2222:22"
+    volumes:
+    - ./data:/app/data

go.mod

@@ -4,4 +4,4 @@ go 1.21.5
 
 require golang.org/x/crypto v0.17.0
 
-require golang.org/x/sys v0.15.0
+require golang.org/x/sys v0.15.0 // indirect

main.go

@@ -1,26 +1,41 @@
 package main
 
 import (
+	"bufio"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
-	"log"
 	"net"
-	"strconv"
+	"os"
 	"time"
 
 	"golang.org/x/crypto/ssh"
 )
 
 func main() {
+	path := os.Getenv("PATH")
+	if path == "" {
+		path = "/var/log/ssh-honeypot.log"
+	}
 
-	port := 22
+	logFile, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+	if err != nil {
+		panic(err)
+	}
+	defer logFile.Close()
+
+	w := bufio.NewWriter(logFile)
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "22"
+	}
 
 	key, err := generateKeyPair()
 	if err != nil {
-		log.Fatalf("Failed to generate key pair: %v", err)
+		panic(err)
 	}
 
 	config := &ssh.ServerConfig{
@@ -29,24 +44,30 @@ func main() {
 			if err != nil {
 				ip = c.RemoteAddr().String()
 			}
-			log.Printf("[%s] \"honeypot connection attempt: ssh - %s - %s - %s\"\n", time.Now().Format("2006-01-02 15:04:05.000"), ip, c.User(), string(pass))
+			_, err = fmt.Fprintf(w, "[%s] \"honeypot connection attempt: ssh - %s - %s - %s\"\n", time.Now().Format("2006-01-02 15:04:05.000"), ip, c.User(), string(pass))
+
+			if err != nil {
+				fmt.Printf("Error writing to log file: %v", err)
+			}
+
+			w.Flush()
+
 			return nil, fmt.Errorf("password rejected for %q", c.User())
 		},
 	}
 
 	config.AddHostKey(key)
 
-	// Listen on port 22
-	listener, err := net.Listen("tcp", "0.0.0.0:"+strconv.Itoa(port))
+	listener, err := net.Listen("tcp", "0.0.0.0:"+port)
 	if err != nil {
-		log.Fatalf("Failed to listen on port %d: %v", port, err)
+		panic(err)
 	}
-	log.Printf("Listening on port %d...", port)
+	fmt.Printf("Listening on port %s...", port)
 
 	for {
 		conn, err := listener.Accept()
 		if err != nil {
-			log.Printf("Failed to accept incoming connection: %s", err)
+			fmt.Printf("Failed to accept incoming connection: %s", err)
 			continue
 		}
 
@@ -55,19 +76,16 @@ func main() {
 }
 
 func generateKeyPair() (ssh.Signer, error) {
-	// Generate a new RSA private key
 	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
 		return nil, err
 	}
 
-	// Encode the private key to PEM format
 	privateKeyPEM := pem.EncodeToMemory(&pem.Block{
 		Type:  "RSA PRIVATE KEY",
 		Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
 	})
 
-	// Parse the PEM encoded private key to get an ssh.Signer
 	signer, err := ssh.ParsePrivateKey(privateKeyPEM)
 	if err != nil {
 		return nil, err