PASO 1
Instala el repositorio de EPEL
http://fedoraproject.org/wiki/EPEL
PASO 2
ejecutamos en shell
#yum --skip-broken install firebird-* php-interbase php-pdo*
y
#yum install firebird
PASO 3
iniciamos firebird y reiniciamos apache
#/etc/init.d/httpd restart
#/etc/init.d/firebird-superserver start
y listo 
interbase
| Firebird/InterBase Support | dynamic | 
| Compile-time Client Library Version | Firebird API version 25 | 
| Run-time Client Library Version | LI-V6.3.1.26351 Firebird 2.5 | 
| Directive | Local Value | Master Value | 
|---|---|---|
| ibase.allow_persistent | On | On | 
| ibase.dateformat | %Y-%m-%d | %Y-%m-%d | 
| ibase.default_charset | no value | no value | 
| ibase.default_db | no value | no value | 
| ibase.default_password | no value | no value | 
| ibase.default_user | no value | no value | 
| ibase.max_links | Unlimited | Unlimited | 
| ibase.max_persistent | Unlimited | Unlimited | 
| ibase.timeformat | %H:%M:%S | %H:%M:%S | 
| ibase.timestampformat | %Y-%m-%d %H:%M:%S | %Y-%m-%d %H:%M:%S | 
PDO
| PDO support | enabled | 
|---|---|
| PDO drivers | firebird, mysql, odbc, pgsql, sqlite | 
PDO_Firebird
| PDO Driver for Firebird/InterBase | enabled | 
|---|
