I followed this tutorial here http://articles.slicehost.com/2008/1/30/centos-setup-page-1 to set up my iptables. However, I found I couldn't access FTP server anymore. I then came across this article http://www.cyberciti.biz/faq/iptables-open-ftp-port-21/, but I am still unable to access FTP server after adding the rules from the second tutorial article. I am wondering how to set the iptables to allow FTP connection. I'm using CentOS 5.