Simple Windows remote control API service (python 3 + flask)

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I like when EVA ICS (https://www.eva-ics.com) automatically turns on my computer when I come to office and puts it to sleep when I go. I was too lazy to program this correctly in past and simply used telnet server on machine to let remote script login and execute sleep command. But I've upgraded my computer to Windows 10 and found telnet server is no longer available.

Then, as default MS Windows RPC is very complex, I've decided to write a simple python service to provide control API. The problem is it's not well documented and need you to know a couple of tricks.

This is an example of 100% working python + flask service for Windows.

So, let's go, we have 2 files:

wincontrol.py

If started with "app" option, launches flask application, otherwise starts to win32serviceutil params handler.

Options:

• app - launch web application

• install - install a service (SimpleWinControlAPI / can be found as Windows Remote Control Simple API in service list)

• remove - remove a service

(run wincontrol.py ---help for all available)

wincontrol.yml

Service configuration. Set here access-key, listen host:port, hosts acl and list of available commands (note that they'll be executed by SYSTEM).

In real life, make sure the file has correct permissions (not readable by users).

Installing required libraries

Execute:

pip install pywin32 flask pyyaml netaddr

API

Has only a couple of functions:

• GET /state - returns { "ok": true }

• POST /command/<cmd> - executes command, returns 404 if command is not defined, ok:true if command is executed correctly or ok:false if exit code was not zero.

Access key should be set in X-Auth-Key request header. Remote IP should match hosts-allow acl if defined.

E.g. by default, request

curl -X POST -H x-auth-key:123 ip-of-windows-machine/command/sleep

will run

rundll32.exe powrprof.dll,SetSuspendState 0,1,0

and put the computer to sleep. Bingo! )

Dealning with 1053 service error

• Make sure python is in PATH for all users.

• Make sure pywintypesXX.dll file is in PATH. If no - copy it to the python root folder (e.g. if you have python 3.7 installed in c:\python37 - copy pywintypes37.dll from c:\python37\Lib\site-packages\pywin32_system3 to c:\python37

• If the service is started, but flask app failed with an exception, it will be written to wincontrol-error.log (in the folder where python script is located)

Nuts and bolts

The main problem I found - it's never noted that when python script is started as service, it has no sys.stdout and sys.stderr set. So when any library want to exec sys.stdout.write or sys.stdout.flush(), it will immediately cause an exception, because sys.stdout is actually set to None.

So I've put a simple dummy stdout/stderr to prevent this.