Concurrent MSYS2/Cygwin SSHD for Windows

This is a script for installing MSYS2 sshd on port 2222 to run concurrently with the native OpenSSH sshd for Windows.

It also works for Cygwin, in which case the Cygwin ssh can also run concurrently with the MSYS2 sshd on the default port of 2223.

It is a fork of this popular gist for installing MSYS2 sshd:

https://gist.github.com/samhocevar/00eec26d9e9988d080ac

This allows full terminal capability in MSYS2, which is currently not possible with the native OpenSSH sshd or terminal.

Options

The port can be specified with the --port or -p option, you can also edit sshd_config after installation and restart the service (/etc/ssh/sshd_config on MSYS2 and /etc/sshd_config on Cygwin.)

The service name is msys2_sshd for MSYS2 and cygwin_sshd for Cygwin.

To uninstall the service, use --uninstall or -u.

Home Directory Location

If you want to use your Windows profile directory as your MSYS2 or Cygwin home directory, put the following in /etc/nsswitch.conf:

db_home: windows

If you choose to do this, I recommend adding the following to your ~/.bashrc:

alias ls="ls -h --color=auto --hide='ntuser.*' --hide='NTUSER.*'"

Installation

Download the script and read it,

For (powershell):

iwr https://raw.githubusercontent.com/rkitover/windows-alt-sshd-msys2/master/msys2-alt-sshd-setup.sh -outfile msys2-alt-sshd-setup.sh
more msys2-alt-sshd-setup.sh

. And for (bash or cmd.exe):

curl -LO "https://raw.githubusercontent.com/rkitover/windows-alt-sshd-msys2/master/msys2-alt-sshd-setup.sh"
more msys2-alt-sshd-setup.sh

. Press Win + X and run the Administrator PowerShell or cmd prompt.

Start a privileged bash shell on MSYS2:

/msys64/usr/bin/bash -l

, if you installed MSYS2 with Chocolatey, it would instead be:

/tools/msys64/usr/bin/bash -l

. And on Cygwin:

/cygwin64/bin/bash -l

, or if you installed MSYS2 with Chocolatey, it would instead be:

/tools/cygwin/bin/bash -l

. Go to the directory where you downloaded the script and run it:

bash msys2-alt-sshd-setup.sh

. The firewall rule is created automatically.

OpenSSH Setup

The script configures OpenSSH automatically to create aliases for your MSYS2 or Cygwin sessions.

You must install OpenSSH for Windows to use this, it can be installed via the openssh chocolatey package.

If you want to do this yourself here are the details:

Edit ~/.ssh/config and add the following:

Host msys2
  HostName localhost
  Port 2222
  RequestTTY yes
  RemoteCommand MSYSTEM=MSYS exec bash -l

Host mingw64
  HostName localhost
  Port 2222
  RequestTTY yes
  RemoteCommand MSYSTEM=MINGW64 bash -l

Host mingw32
  HostName localhost
  Port 2222
  RequestTTY yes
  RemoteCommand MSYSTEM=MINGW32 bash -l

, the scripts also adds all the other MSYSTEM environments, the full list is here.

For Cygwin it would be:

Host cygwin
  HostName localhost
  Port 2223

. If you are doing this on a remote host, replace localhost with your Windows host.

This can be done on Windows or Linux etc..

Then to connect to the MSYS2 sshd you would simply run:

ssh msys2

, or

ssh mingw64

, or to connect to Cygwin:

ssh cygwin

, etc..

Passwordless SSH

To not require a password to connect to your MSYS2/Cygwin sshd, the script automatically sets up an authorized_keys file for you with a key if you do not have one.

To do this yourself:

First, if you do not already have an ssh key, generate one:

ssh-keygen -t rsa -b 4096
ssh-add ~/.ssh/id_rsa

. You can leave the passphrase empty, if you do set it, the ssh-agent service will store it for you so you are not asked for it constantly.

Then add your public key to authorized_keys to allow key authentication instead of using a password. NOTE: this is the authorized_keys in your MSYS2 or Cygwin home directory, assuming you're not using your Windows home directory.

So from an MSYS2 or Cygwin shell you would do:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
cat "${USERPROFILE}/.ssh/id_rsa.pub" >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

. Note that the Windows sshd does not by default use this location for the authorized_keys file for users in the Administrators group. In this case, this does not matter because the MSYS2/Cygwin sshd does, but if you set your MSYS2/Cygwin home directory to your profile directory, and you are in the Administrators group, and you want to use the same authorized_keys file for both, then edit C:\ProgramData\ssh\sshd_config and comment out these lines by putting a # in front of each one:

Match Group administrators
       AuthorizedKeysFile __PROGRAMDATA__/ssh/administrators_authorized_keys

. This can be done with this command:

sed -i 's/.*administrators.*/#&/g' /programdata/ssh/sshd_config

. Make sure to fix the permissions on the ~/.ssh files in your profile directory by running the following from PowerShell:

&(resolve-path /prog*s/openssh*/fixuserfilepermissions.ps1)
import-module -force $(resolve-path /prog*s/openssh*/opensshutils.psd1)
repair-authorizedkeypermission -file ~/.ssh/authorized_keys

, the script does this as well.

Microsoft Windows Terminal Setup

This requires OpenSSH set up as described in OpenSSH Setup and Passwordless SSH. The script does both of these steps automatically.

To create MSYS2 entries in the terminal session drop-down, add the following to your settings.json in the profiles section:

{
    "name": "MSYS2 - MSYS",
    "icon": "file://C:/msys64/msys2.ico",
    "commandline": "ssh msys2"
},
{
    "name": "MSYS2 - MINGW64",
    "icon": "file://C:/msys64/msys2.ico",
    "commandline": "ssh mingw64"
},
{
    "name": "MSYS2 - MINGW32",
    "icon": "file://C:/msys64/msys2.ico",
    "commandline": "ssh mingw32"
},

. A Cygwin entry might look like this:

{
    "name": "Cygwin",
    "icon": "file://C:/cygwin64/Cygwin-Terminal.ico",
    "commandline": "ssh cygwin"
},

.

Restarting on Package Upgrades

When you do MSYS2 or Cygwin upgrades, if core components are updated it will kill all processes including the sshd service process, before you can connect again you must run:

start-service msys2_sshd
# or for Cygwin
start-service cygwin_sshd

, in an Administrator PowerShell prompt, or from an Administrator cmd.exe prompt:

net start msys2_sshd
@rem or for Cygwin
net start cygwin_sshd

.

Limitations

It is not possible to run GUI apps from these ssh sessions directly, the reason for this is described here.

However, there is a workaround.

Just start a tmux session in mintty, detach from it, then attach to it in the ssh session, and you will be able to launch GUI apps.