Basic iptables configuration

iptables.sh

trustedIP="1.2.3.4/32"

cat <<- EOF > /etc/iptables/rules.v4
	# Generated by iptables-save v1.8.7 on Wed Mar 29 14:37:32 2023
	*filter
	:INPUT DROP [0:0]
	:FORWARD DROP [0:0]
	:OUTPUT ACCEPT [0:0]
	-A INPUT -i lo -j ACCEPT
	-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
	-A INPUT -p tcp -m tcp --dport 5093 -j ACCEPT
	-A INPUT -s $trustedIP -j ACCEPT
	-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
	-A INPUT -m conntrack --ctstate INVALID -j DROP
	-A INPUT -j REJECT
	-A OUTPUT -o lo -j ACCEPT
	-A OUTPUT -p udp -m udp -j ACCEPT
	-A OUTPUT -m conntrack --ctstate ESTABLISHED -j ACCEPT
	COMMIT
	# Completed on Wed Mar 29 14:37:32 2023
EOF

cat <<- 'EOF' > /etc/iptables/rules.v6
	# Generated by ip6tables-save v1.8.7 on Thu Mar 30 06:30:12 2023
	*filter
	:INPUT ACCEPT [0:0]
	:FORWARD ACCEPT [0:0]
	:OUTPUT ACCEPT [0:0]
	-A INPUT -i lo -j ACCEPT
	-A INPUT -p ipv6-icmp -j ACCEPT
	-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
	-A INPUT -d fe80::/64 -p udp -m udp --dport 546 -m state --state NEW -j ACCEPT
	-A INPUT -j REJECT --reject-with icmp6-adm-prohibited
	-A FORWARD -j REJECT --reject-with icmp6-adm-prohibited
	COMMIT
	# Completed on Thu Mar 30 06:30:12 2023
EOF