ejabberdはXMPPサーバーツール。
yum install epel-release yum --enablerepo=epel-testing install ejabberd systemctl start ejabberd
参考
https://centos.pkgs.org/7/epel-testing-x86_64/ejabberd-15.07-4.el7.x86_64.rpm.html
https://gist.github.com/jll90/1d52515aa24f2585572d4d164056cc42