sure you install the non-free version of RAR via Synaptic Package Manager.
Initially, I installed the free version ( unrar-free 1:0.0.1 ) but got
the following error message: -
unrar-free: invalid archive 'RenovationsSoftv1.rar': Value too large for
defined data type
when I attempted to extract files from a 6.8 GB archive.
Once I installed, and used, the non-free version ( unrar 1:220.127.116.11 ),
all was well.