Today I came across an extremely useful tool.

Want to give SCP access without SSH access?

A program called rssh was just the trick.

To install it on Ubuntu, simply type apt-get install rssh

To use it follow the example below:

For a new user:

useradd -m -d /home/scptestuser -s /usr/bin/rssh scptestuser
passwd scptestuser

Or for an existing user:

chsh -s /usr/bin/rssh scptestuser

Then edit /etc/rssh.conf to configure rssh shell – especially uncomment allowscp line to enable SCP access for all rssh users.