Firewall ports

From xcat

xCAT requires the following ports to be open on the network:

port 69 - TFTP (do udp/tcp)
port 300 - for awk communication (tcp) during node discovery
port 623 - for IPMI traffic (udp/tcp)
port 161/162 - for SNMP communication to blade chassis (udp/tcp)
port 22 - for SSH

I'll put more information on how to set iptables soon. There may also be other ports. We should also probably put a table in here for doing selinux.