[root@OEL6 Downloads]# uname -r
2.6.32-100.34.1.el6uek.x86_64

After I downloaded and unzipped OracleXE 11.2 Beta, I run:

[root@OEL6 Downloads]# rpm -Uvh oracle-xe-11.2.0-0.5.x86_64.rpm 
Preparing...                ########################################### [100%]
error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key
error: "net.bridge.bridge-nf-call-iptables" is an unknown key
error: "net.bridge.bridge-nf-call-arptables" is an unknown key
error: %pre(oracle-xe-11.2.0-0.5.x86_64) scriptlet failed, exit status 255
error:   install: %pre scriptlet failed (2), skipping oracle-xe-11.2.0-0.5

Google helped me find a simple workaround, if you run the same command again it’ll install OracleXE without error:

[root@OEL6 Downloads]# rpm -Uvh oracle-xe-11.2.0-0.5.x86_64.rpm 
Preparing...                ########################################### [100%]
   1:oracle-xe              ########################################### [100%]
Executing post-install steps...
You must run '/etc/init.d/oracle-xe configure' as the root user to configure the database.