[CentOS] IPTables not working?

> RH-Firewall-1-INPUT  all  --  anywhere         anywhere
> DROP       all  --  ip176-0.netcathost.com/24  anywhere

wrong order - if the RH Firewall accepts it it won't be dropped...
you want:

> Chain INPUT (policy ACCEPT)
> target     prot opt source                     destination
> DROP       all  --  ip176-0.netcathost.com/24  anywhere
> RH-Firewall-1-INPUT  all  --  anywhere         anywhere