Subject Re: Start service of Firebird 2.5 in Centos 7
Hello how did you installed it ? 
On Centos7 you need epel repository


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 :

systemctl start firebird-superclassic.service

If you want to have firebird started at each boot, as root :
  for SuperClassic :  systemctl enable firebird-superclassic.service