I use sport for these specific rules, is there any reason I shouldn't and probably use dport?
Code:
iptables -A OUTPUT -p udp -m udp --sport 67 --dport 68 -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p udp -m udp --sport 123 --dport 123 -m state --state NEW -j ACCEPT
iptables -N RULE_17
iptables -A OUTPUT -p tcp -m tcp --dport 20:21 -j RULE_17
iptables -A OUTPUT -p tcp -m tcp --sport 1024: --dport 1024: -j RULE_17
iptables -A RULE_17 -j LOG --log-level info --log-prefix "RULE 17 -- ACCEPT"
iptables -A RULE_17 -j ACCEPT