EPEL 7 left the beta stage so you can install Firebird 2.5.3 packages for Centos/RHEL 7 from stable repository

sudo yum install http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-1.noarch.rpm

yum –enablerepo=epel install firebird-superclassic

and since EPEL 7 use Systemd, you can use Systemd to enable the service

and stop or start it

read the README provided :

http://pkgs.fedoraproject.org/cgit/firebird.git/tree/README.Fedora?h=epel7

you also have classic and superserver

http://dl.fedoraproject.org/pub/epel/7/x86_64/repoview/firebird.html

http://dl.fedoraproject.org/pub/epel/7/x86_64/repoview/firebird-classic.html

http://dl.fedoraproject.org/pub/epel/7/x86_64/repoview/firebird-superserver.html