I've installed a debian stretch container in docker (via portainer.io) and was able to install openssh-server via apt-get install.
After a successful connection with PuTTY, i'm not able to install usbmount which i need for later purpose..
i searched a lot and went through different repositories but nothing helped - i'm getting the same error every time.
of course, i typed in apt-get update after every edit of sources.list
by looking for another solution i've tried to install apt-file and for some reason this works, but usbmount wont...
this is the content of my /etc/apt/sources.list
deb http://deb.debian.org/debian/ stable main contrib non-free
deb-src http://deb.debian.org/debian/ stable main contrib non-free
deb http://deb.debian.org/debian/ stable-updates main contrib non-free
deb-src http://deb.debian.org/debian/ stable-updates main contrib non-free
deb http://deb.debian.org/debian-security stable/updates main
deb-src http://deb.debian.org/debian-security stable/updates main
deb http://ftp.debian.org/debian stretch-backports main
deb-src http://ftp.debian.org/debian stretch-backports main
any suggestions? thanks in advance