De acordo com o fwbuilder (recomendado) e uma rápida inspeção, o seguinte faz os testes 1 e 3. Fazer (2) depende strongmente da sua definição de "interno" (na interface, duas interfaces, etc.)
$IPTABLES -N RULE_0
$IPTABLES -A INPUT -p tcp -m tcp -s 1.2.3.4 --dport 22 -m state --state NEW -j RULE_0
$IPTABLES -A FORWARD -p tcp -m tcp -s 1.2.3.4 --dport 22 -m state --state NEW -j RULE_0
$IPTABLES -A RULE_0 -j LOG --log-level info --log-prefix "RULE 0 -- ACCEPT "
$IPTABLES -A RULE_0 -j ACCEPT
#
# Rule 1 (global)
#
echo "Rule 1 (global)"
#
$IPTABLES -N RULE_1
$IPTABLES -A OUTPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j RULE_1
$IPTABLES -A INPUT -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j RULE_1
$IPTABLES -A FORWARD -p tcp -m tcp -m multiport --dports 80,443 -m state --state NEW -j RULE_1
$IPTABLES -A RULE_1 -j LOG --log-level info --log-prefix "RULE 1 -- ACCEPT "
$IPTABLES -A RULE_1 -j ACCEPT
Por exemplo para uma rede interna 192.168.1.0/254:
$IPTABLES -N In_RULE_0
$IPTABLES -A INPUT -i eth0:1 -p tcp -m tcp -s 192.168.1.0/24 -d 192.168.1.0/24 --dport 3306 -m state --state NEW -j In_RULE_0
$IPTABLES -A FORWARD -i eth0:1 -p tcp -m tcp -s 192.168.1.0/24 -d 192.168.1.0/24 --dport 3306 -m state --state NEW -j In_RULE_0
$IPTABLES -A In_RULE_0 -j LOG --log-level info --log-prefix "RULE 0 -- ACCEPT "
$IPTABLES -A In_RULE_0 -j ACCEPT
$IPTABLES -N Out_RULE_0
$IPTABLES -A OUTPUT -o eth0:1 -p tcp -m tcp -s 192.168.1.0/24 -d 192.168.1.0/24 --dport 3306 -m state --state NEW -j Out_RULE_0
$IPTABLES -A FORWARD -o eth0:1 -p tcp -m tcp -s 192.168.1.0/24 -d 192.168.1.0/24 --dport 3306 -m state --state NEW -j Out_RULE_0
$IPTABLES -A Out_RULE_0 -j LOG --log-level info --log-prefix "RULE 0 -- ACCEPT "
$IPTABLES -A Out_RULE_0 -j ACCEPT