Remote Control with http

Motion can be remote controlled via a simple http interface. http is the language a normal web browser talks when it requests a web page. The web server answers back with some simple http headers followed by a webpage coded in HTML.

Most Motion config options can be changed while Motion is running except options related to the size of the captured images and mask files which are loaded only when Motion starts. So only your fantasy sets the limit to what you can change combining cron and the remote control interface for Motion.

So the most obvious tool to use to remote control Motion is any web browser. All commands are sent using the http GET method which simply means that the information is sent via the URL and maybe a query string. You can use any browser (Firefox, Mozilla, Internet Explorer, Konquerer, Opera etc). You can also use the text based browser lynx to control Motion from a console. It navigates fine through the very simple and minimalistic http control interface of Motion.

The details about how to control Motion via the URL is described in detail in the Motion http API topic.

But it is probably simpler to connect to the control port with a browser, navigate to the function you want, and copy the URL from the browser URL entry line. If your control_port is 8080 and you browse from the same machine on which Motion runs simply look up http://localhost:8080/ and navigate around. Connecting from a remote machine is done by using a domain name (example http://mydomain.com:8080/) or the IP address of the machine (example http://192.168.1.4:8080/). The option control_localhost must be off to allow connection from a remote machine.

If you want to use a script or cron to automatically change Motion settings while Motion runs you use a program that can fetch a webpage. We simply just throw away the html page that Motion returns. Programs commonly available on Linux machines are wget and lwp-request. Here is an example of how to start and stop motion detection via cron. These two lines are added to /etc/crontab.

0 9 * * * root /usr/bin/lwp-request http://localhost:8080/0/detection/start > /dev/null
0 18 * * * root /usr/bin/lwp-request http://localhost:8080/0/detection/pause > /dev/null

If you want to use the http remote control from your own software (for example your own PHP front end) you can set the new motion.conf option html_output off. Then Motion answers back with very basic text only and no html around it. A bit like the xmlrpc interface did.

To remote control Motion from a web pages you can for example use PHP. In PHP it takes this simple code line to send a remote commend to Motion. Here we pause motion detection for camera 2

readfile('http://localhost:8080/2/detection/pause');

What happened to XMLRPC?

XMLRPC is replaced by a simpler http remote control interface. It is still being worked on but it is absolutely useable now and much nicer to work with than xmlrpc. Another advantage is that you do not need to install xmlrpc libraries. It is all written in standard C.

Security Warning! Note that this feature also means you have to pay attention to the following.

• Anyone with access to the remote control port (http) can alter the values of any options and save files anywhere on your server with the same privileges as the user running Motion. They can execute any command on your computer with the same privileges as the user running Motion. Anyone can access your control port if you have not either limited access to localhost or limited access using firewalls in the server. You should always have a router between a machine running Motion with remote control enabled and the Internet and make sure the Motion control port is not accessible from the outside.
• If you limit control port to localhost you still need to take care of any user logging into the server with any kind of terminal session.
• It is a good idea to run Motion as a harmless user. Not as root!!

These are the config file options that control Motion.

These must be placed in motion.conf and not in a thread config file.

-- KennethLavrsen - 12 Apr 2005