I have a couple CentOS boxes running in our DMZ and although they are running behind a firewall, I'm also running iptables. One thing I cannot do it yum update. What ports are required for this? I have outbound http open and I can browse to sites using firefox. If I run an ethereal scan the process seems to stop with DNS queries, but I can resolve mirrorlist.centos.org without a problem. Anyone know what the problem could be? If I stop iptables everything works of course. Thanks, James