License File created with world-readable modes.

Hi Jamie,

since yesterday I have a pro license. I've seen, if the license is installed via the WUI, the file /etc/virtualmin-license is created with mode 644.

So every user with access to the system can happily cat the file and get a virtualmin license for free.

I think mode 600 is the better one ;)

I've changed that on my system already.

ciao, Marc