I run my own VPS with NGINX and PHP-FPM on Debian 7.
I have not been able to get EWWW to see/use the image optimisation plugins.
I assume this is something to do with NGINX or PHP-FPM permissions but I haven't been able to figure it out.
I've tried copying the plugins to /usr/bin but I don't think that's the issue as the debug log states it can see and check the files in wp-content/ewww. Also tar is installed but the plugin is not able to see that either.
Plugin status and debug log: http://pastebin.com/HEuRQdE5
Any help would be much appreciated.