Installing SFTP/SSH Server on Windows using OpenSSH

Recently, Microsoft has released an early version of OpenSSH for Windows. You can use the package to set up an SSH/SFTP server on Windows.

Installing FTP Server
Setting up SSH public key authentication
Running the server
Connecting to the server
Further reading

Installing FTP Server

Download the latest OpenSSH for Windows binaries (package OpenSSH-Win32.zip)
Extract the package to a convenient location (we will use C:\openssh in this guide)

Generate server keys by running the following commands from the C:\openssh (when asked for a passphrase, just press Enter, as the server keys cannot be protected with a passphrase):

ssh-keygen.exe -t rsa -f ssh_host_rsa_key
ssh-keygen.exe -t dsa -f ssh_host_dsa_key
ssh-keygen.exe -t ecdsa -f ssh_host_ecdsa_key
ssh-keygen.exe -t ed25519 -f ssh_host_ed25519_key

Open a port for the SSH server in Windows Firewall:
- Either run the following PowerShell command (Windows 8 and 2012 or newer only), as an Administrator:
  New-NetFirewallRule -Protocol TCP -LocalPort 22 -Direction Inbound -Action Allow -DisplayName SSH
- or go to Control Panel > System and Security > Windows Firewall > Advanced Settings > Inbound Rules and add a new rule for port 22.
To allow a public key authentication, as an Administrator, run:
C:\openssh\setup-ssh-lsa.cmd
and restart the machine
In C:\openssh\sshd_config locate a Subsystem sftp directive and change the path to sftp-server to its Windows location:
Subsystem sftp C:\openssh\sftp-server.exe
Download PsTools and extract PsExec.exe to C:\openssh

These instructions are partially based on the official deployment instructions.

Setting up SSH public key authentication

Follow a generic guide for Setting up SSH public key authentication in *nix OpenSSH server, with following differences:

Create the .ssh folder (for the authorized_keys file) in your Windows account profile folder (typically in C:\Users\username\.ssh).
Do not change permissions for the .ssh and the authorized_keys.

Running the server

To start the server, run the following command as an Administrator:

C:\openssh\PsExec.exe -i -s -w "C:\openssh" C:\openssh\sshd.exe

The OpenSSH for Windows does not support running as a service yet, but it should be available soon.

Connecting to the server

Before the first connection, find out fingerprint of the server’s RSA key by running ssh-keygen.exe -l -f ssh_host_rsa_key -E md5 from the C:\openssh:

C:\openssh>ssh-keygen.exe -l -f ssh_host_rsa_key -E md5
2048 MD5:94:93:fe:cc:c5:7d:d8:2a:33:21:0e:f3:91:11:8a:d9 martin@example (RSA)

Start WinSCP. Login dialog will appear. On the dialog:

Make sure New site node is selected.
On New site node, make sure the SFTP protocol is selected.
Enter your machine/server IP address (or a hostname) into the Host name box.
Enter your Windows account name to the User name box.
For a public key authentication:
- Press the Advanced button to open Advanced site settings dialog and go to SSH > Authentication page.
- In Private key file box select your private key file.
- Submit Advanced site settings dialog with the OK button.
For a password authentication:
- Enter your Windows account password to the Password box.
- If you Windows account does not have a password, you cannot authenticate with the password authentication (i.e. with an empty password), you need to use the public key authentication.
Save your site settings using the Save button.
Login using Login button.
Verify the host key by comparing fingerprint with the one collected before (see above).