how to block
 

Hai friends how can I block accessing some sites through internet on rhel 5.


Thanks in advance

One option is to DROP or REJECT packets on the OUTPUT chain (using iptables) for selected IP addresses. If that's not what your looking for, perhaps you can phrase the question a little more precisely?

If this refers to blocking other people, then look at squid.

If this refers to you, then maybe something like moblock or pg4linux.