mjhjmtu

i am using iptables to allow certain IPs(users) to allow specific ports.
Like so -

ACCEPT tcp -- 1.2.3.4 anywhere tcp dpts:4358:4362

So for each IP address I have multiple ranges of ports allowed.

The thing is some of the users have dynamic IPs, and I have tried to get them signed up for dynamic dns service, but iptables is automatically resolving that domain to their current IP, so for now I am sticking with bare IPs.

The question is, how to update multiple rules IPs?
Something like find and replace in notpad )

iptables can only store IP addresses in the kernel tables, which is why it resolves the hostnames to the current IP addresses when run.

The only way to handle updates to IP adresses is to remove the old rules and add the new rules. I suggest adding these rules to a separate table, so that only the separate table needs to be cleared and reloaded. Something like:

Setup:

iptables -N DYNUSERS
iptables -A INPUT -j DYNUSERS

Building the DYNUSERS table:

iptables -F DYNUSERS
iptables -A DYNUSERS -s dyndns1.example.com -p tcp --dport 4358:4362 -j ACCEPT
iptables -A DYNUSERS -s dyndns2.example.com -p tcp --dport 4358:4362 -j ACCEPT

When the IP addresses change, simply run the last part again. Perhaps schedule this for every hour or so.