How do you PREPEND an iptables rather than APPEND?

Question

Pretty basic question.. How do you PREPEND an iptables rather than APPEND?

I have DROP statements at the bottom of my rules. I have software to add new rules but adding rules after DROP statements isn't good. Every time I want to add a new rule I have to flush the table which is inefficient. Is there a way to prepend a rule i.e. add a rule to the top of the table rather than the bottom?

Many thanks.

Answer 1

Use the -I switch:

sudo iptables -I INPUT 1 -i lo -j ACCEPT would insert a rule at position #1 in the INPUT chain.

Answer 2

-I will insert. You're probably using -A to append.

You can also do iptables -I chain rulenum to insert a rule as number "rulenum" in chain "chain". -R chain rulenum can be used to replace a specific rule at number "rulenum" in chain "chain". iptables -L -n --line-numbers will show the rule numbers in the left-most column.