Thanks Alan for your suggestion. I tried to install freeradius2.1.8, but ran into following error:

pateldil@pateldil-desktop:~/freeradius-server-2.1.8[17:00:07]$ sudo dpkg -i ../freeradius_2.1.8+git_amd64.deb
Selecting previously deselected package freeradius.
(Reading database ... 179982 files and directories currently installed.)
Unpacking freeradius (from .../freeradius_2.1.8+git_amd64.deb) ...
dpkg: dependency problems prevent configuration of freeradius:
 freeradius depends on libfreeradius2 (= 2.1.8+git); however:
  Version of libfreeradius2 on system is 2.1.0+dfsg-0ubuntu4.1.
dpkg: error processing freeradius (--install):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 freeradius


Can't figure out an easy way to install libfreeradius2 (= 2.1.8+git.).

Anyways, thanks for your suggestion.