dyniptables

rebuild dynamic IPtables chain with DNS lookups of named hosts

Server prep and usage:

1. Place script in /usr/local/sbin/dyniptables.sh (root:root, 0744)
2. Add to system on-boot iptables rules a new filter chain and (j)ump:

   :DYNAMIC - [0:0]
   -A INPUT -j DYNAMIC
   

   ...where DYNAMIC is the name of the $DCHAIN in dyniptables.conf
3. Add to root's crontab a refresh every 6 hours:

   5 */6 * * * /usr/local/sbin/dyniptables.sh
   

4. Add an override.conf to systemd iptables startup:

   DEB clones: `systemctl edit netfilter-persistent.service`
    or
   RPM clones: `systemctl edit iptables.service`              (IPv4)
               `systemctl edit ip6tables.service`             (IPv6)
   
   [Service]
   ExecStartPost=/usr/local/sbin/dyniptables.sh     # (DEB, all rules)
    or
   ExecStartPost=/usr/local/sbin/dyniptables.sh -4  # (RPM, IPv4 only)
   ExecStartPost=/usr/local/sbin/dyniptables.sh -6  # (RPM, IPv6 only)
   

SPDX-License-Identifier: MIT