--tftp-root=<directory>[,<interface>]
Look for files to transfer using TFTP relative to the given
directory. When this is set, TFTP paths which include ".." are
rejected, to stop clients getting outside the specified root.
Absolute paths (starting with /) are allowed, but they must be within
the tftp-root. If the optional interface argument is given, the
directory is only used for TFTP requests via that interface.