Go to http://pkgs.repoforge.org/rpmforge-release/ and get latest rpm

[cc lang="bash"]
\$ wget http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
\$ rpm -i rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
\$ yum install rar unrar
[/cc]