Problem: After installing Oracle E-Business Suit or after installing Oracle database 11.x.xx.xx Software on OEL 5.x Server, trying to connect the database "sqlplus /nolog" or trying to start the lsnrctl, getting the below error message : case1: command : sqlplus /nolog Error: "sqlplus: error while loading shared libraries: <ORACLE_HOME>/lib/libnnz11.so: cannot restore segment prot after reloc: Permission denied" case 2: command : lsnrctl start <SID_NAME> Error: lsnrctl: error while loading shared libraries: <ORACLE_HOME> /lib/libnnz11.so: cannot restore segment prot after reloc: Permission denied Cause: According to Metalink Note: 454196.1 - libnnz11.so: cannot restore segment prot after reloc: Permission denied and ./sqlplus: error on libnnz11.so: cannot restore segment prot after reloc [ID 454196.1] , it's SELinux causing this problem. Solution: Disable SELinux Switch SELinux