SFTP server

SFTP server

This article relies on the following:

Accessing web interface / command-line interface
Managing configs / packages / services / logs

Introduction

This how-to describes the method for setting up SFTP server on OpenWrt.
It relies on Dropbear and openssh-sftp-server for secure authentication and file transfer.
You can use any suitable SFTP client running natively on your OS.

Goals

Transfer files to/from the router.
Secure file transfer operations.
Support OS specific clients.

Instructions

The SSH File Transfer (SFTP) is a file transfer protocol that works over SSH. It's like SCP but has more features. For a basic usage the low level SCP may be enough but if you need, for example, to mount drive then use the SFTP.

The vanilla OpenWrt out of the box has a small Dropbear SSH server. But it doesn't support the SFTP and you need to install openssh-sftp-server package. The package comes from another OpenSSH server which is bigger but has more features and default on desktop systems like Ubuntu. Many routers with OpenWrt as a stock firmware use it out of the box and the openssh-sftp-server is installed too. So for this routers you really don't need anything to do and just start using it.

But if not then install the required package:

opkg update
opkg install openssh-sftp-server

Testing

Enter the following URL in your SFTP client.

sftp://root@openwrt.lan/

Clients

Windows: WinSCP - an advanced GUI client. Proprietary
Windows: FAR Manager - an advanced Norton Commander like file manager. Supports a plain SCP too. Proprietary
Linux, macOS, FreeBSD: far2l - an open source version of the FAR. GPL-2
Linux, macOS, FreeBSD: Midnight Commander - a Norton Commander like file manager. Supports a plain SCP too. GPL-3
Linux: GNOME Files or KDE Konqueror. GPL-2
Linux: GNOME Déjà Dup - a backup and sync tool. GPL-3
Windows, macOS, Linux, FreeBSD: rclone - a command-line program to manage files on cloud storage. MIT
Linux: SSHFS client
macOS: Cyberduck and MountainDuck. GPL-3.
Android: X-plore File Manager
Android TV, RapberryPI: KODI - a media player for TV. You can put a USB drive to a router and watch your photos, video and audio without any additional software.
SFTP Client list

Troubleshooting

Collect and analyze the following information.

# Restart services
service log restart; service dropbear restart
 
# Log and status
logread -e dropbear; netstat -l -n -p | grep -e dropbear
 
# Runtime configuration
pgrep -f -a dropbear
 
# Persistent configuration
uci show dropbear
ls -l /etc/dropbear; cat /etc/dropbear/authorized_keys
ls -l $(opkg files openssh-sftp-server | grep -e ^/)

Extras

Service discovery

You may want to provide service discovery for clients supporting Bonjour/Zeroconf.

opkg update
opkg install announce

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