David, it appears that your iptables command is invalid and does not match an iptables chain, match or target.
Your iptable command looks to be failing because “RH-Firewall-1-INPUT” is not a valid ip tables chain. Your match (-m) and target (-j) look correct.
You can view configured chains via CLI command iptables -L
Verify there is a chain matching RH-Firewall-1-INPUT which your command says is the name of the chain that isn’t matching.
Typical chains would be INPUT, OUTPUT, and FORWARD that I typically see but there can be others and user defined chains as well.
You can create a new user defined chain to append the iptable entry to by using the iptables -N <chain name> command if you need a new one but I think in this scenario if “RH-Firewall-1-INPUT” is not listed as a valid chain you could substitute just the INPUT chain so the entry would start as “iptables -A INPUT -s …” instead.
I would write this like so;
Iptables INPUT -s 192.168.1.0/24 -m state –state NEW -p udp -dport 123 -j ACCEPT
Hope this helps.
Blake Russo / Blake.Russo@outlook.com