Enable using saved host key

honeypot/server.go

@@ -4,8 +4,11 @@ import (
 	"context"
 	"io"
 	"net"
+	"os"
 	"time"
 
+	gossh "golang.org/x/crypto/ssh"
+
 	"github.uio.no/torjus/apiary/config"
 
 	"github.com/gliderlabs/ssh"
@@ -34,6 +37,25 @@ func NewHoneypotServer(cfg config.HoneypotConfig, store store.LoginAttemptStore)
 		PasswordHandler: hs.passwordHandler,
 		ConnCallback:    hs.connCallback,
 		Handler:         handler,
+		Version:         "OpenSSH_7.4p1 Debian-10+deb9u6",
+	}
+
+	if cfg.HostKeyPath != "" {
+		f, err := os.Open(cfg.HostKeyPath)
+		if err != nil {
+			return nil, err
+		}
+		pemBytes, err := io.ReadAll(f)
+		if err != nil {
+			return nil, err
+		}
+		signer, err := gossh.ParsePrivateKey(pemBytes)
+		if err != nil {
+			return nil, err
+		}
+
+		hs.sshServer.AddHostKey(signer)
+
 	}
 
 	return &hs, nil