cd <your Magento install dir>

find . -type f -exec chmod 600 {} \;
find . -type d -exec chmod 700 {} \;
find . -type f -exec chmod g+r {} \;
find . -type f -exec chmod o+r {} \;
find . -type d -exec chmod g+rx {} \;
find . -type d -exec chmod o+rx {} \;
find ./var -type d -exec chmod g+rwx {} \;
find ./pub/media -type d -exec chmod g+rwx {} \;
find ./pub/static -type d -exec chmod o+rx {} \;