Closing UDP ports in RHL 8.0
 

I have set up RHL 8.0 with DHCP and now have been messing with IPTABLES and such to secure the server. I have MASQUERADING set up for my internal LAN. I have changed the policy for input forward and output to drop (does reject not work? I can't use reject it says it isn't a recognized command). I run port scanners from various utilities not on the RHL machine. They always show UDP ports, but everything else shows locked down (TCP for example never shows up).

I have even made chains to deny udp entire range rules and they still show up... what is up with the UDP ports and not shutting down??????

Could you post your iptables lines related to UDP?

This is what I have put into iptables chains.

Although they show closed on web port scanners they are still shown as probed. Am I doing all I can? Can they be shut down to where they aren't even seen? I have tried INPUT policy DROP (is there another policy instead of drop to use?) and when I used DROP I accept port 80 and yet not all web pages work... what am I missing there? This is my current config using ACCEPT.

Chain INPUT (policy ACCEPT)
target prot opt source destination
REJECT tcp -- anywhere anywhere tcp dpt:ssh reject-with icmp-port-unreachable
REJECT tcp -- anywhere anywhere tcp dpt:sunrpc reject-with icmp-port-unreachable
REJECT udp -- anywhere anywhere udp dpt:bootps reject-with icmp-port-unreachable
REJECT udp -- anywhere anywhere udp dpt:sunrpc reject-with icmp-port-unreachable

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination