1. Introduction

This HOWTO explains how to configure SFTP for use with the Dropbear SSH package. Dropbear is typically used because of its small size. It is pre-installed on OpenWrt.

1.1. What is SFTP?

Secure File Transfer Protocol or SFTP is a protocol that was incorporated as part of SSH. The idea behind SFTP is to have all of the features that FTP has, but transfer both passwords and file data over an encrypted link.

1.1.1. Do You Really Need To Switch to SFTP?

If you happen to come to this webpage only to solve your problems with WinSCP, groups listing and --full-time , be aware that you don't need the following. Instead, change the settings inside WinSCP. Briefly:

turn on Advanced options checkbox in bottom left part of Login dialog in order to see "Environment/SCP"
Session/Protocol:
- SCP mode
Environment/SCP:
- uncheck Lookup user groups
- uncheck Try to get full timestamp
- uncheck Alias LS to display group name

2. Activating Dropbear

Dropbear is a small SSH daemon that comes pre-installed on OpenWrt. However, it is not active by default. To activate Dropbear, change the password. You can do this on the web interface, or use the shell command:

passwd

You will be prompted for a new root password, along with a verification prompt. Once this is done, OpenWrt will disable the telnet daemon and activate the Dropbear SSH daemon.

3. Installing the SFTP module

Update the package list and install the openssh-sftp-server package. You can do this on the web interface, using System - Installed Software, Update package lists, then Install the openssh-sftp-server package. Or use the shell prompt:

ipkg update
ipkg install openssh-sftp-server

4. Windows SFTP clients

Once both SSH and SFTP are installed you will be able to securely access the routers files via a secure connection. Two of the most popular clients that support SFTP are the Putty SFTP client and the FileZilla graphical client. While the FileZilla client is actually built upon the Putty client they will be treated here as if they are two distinct clients.

4.1. FileZilla

The FileZilla client is an ideal choice for most Windows users. The graphical interface and relatively small learning curve allows the user to begin actively using the software immediately.

See the download page and the user’s forum.

4.2. Putty SFTP

Called PSFTP the Putty SFTP client is a robust and stable implementation of the secure file transfer protocol. While good, Putty's client is command-line based. If you are used to graphical clients, use FileZilla instead.

See Putty's download page and Putty's documentation page.

4.3. WinSCP

WinSCP is a Windows program that makes use of code from Simon Tatham's "Putty". It provides a GUI and can be either installed or run from a stand-alone exe without installation.

WinSCP has a shell extension, which is only available if the software is installed on the client machine, that will allow drag-and-drop usability from the WinSCP window to almost any other Explorer windows. For example, one could drag firewall.conf straight to the desktop.

However, if the non-installation method is chosen, e.g., it is run solely from the exe, then drag-and-drop capabilities will be restricted to within the WinSCP window only. The WinSCP windows can provide an interface either like Norton Comander (r) or like Windows (r) Explorer.

The software is free and open-source. You can download it here or visit the home page.