1. Create the repository config file /etc/yum.repos.d/nux-misc.repo

[nux-misc]
name=Nux Misc
baseurl=http://li.nux.ro/download/nux/misc/el7/x86_64/
enabled=0
gpgcheck=1
gpgkey=http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro

2. Install tunctl rpm package

# yum --enablerepo=nux-misc install tunctl