DynFirewall

To help to protect servers from remote attacks such as ssh service 3306 database services, or windows remote desktop. for dynamically updating firewall whitelist based from DNS TXT record

• Use , you can add it to crontab
  python firewall_update_linux.py ip.txt.example.com

• add following line to your iptables configure file
  -A INPUT -m set --match-set trusted src -j ACCEPT
  /etc/sysconfig/iptables

• and Comment out the following line
  You can find this line
  -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT

Change into
#-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT

• If you want automatically create ipset on startup please check systemd-ipset by BroHui
• If you iptables including a Non-existent ipset, iptables service will broken won't start, that's why we need systemd-ipset

DNS TXT record guide:

you can add IPv4 address or subnet. if you want add multiple IP or subnets you can use ',' split, also you can add txt alone for per ip address/subnet

• Example host type record
  ip.txt TXT "1.1.1.1,2.2.2.2/32"
  ip.txt TXT "3.3.3.3"
  ip.txt TXT "4.4.4.0/24"

Windows Server 2012 Later

• You can use pyinstaller to Build EXE binary
  pyinstaller -F firewall_update_win.py
• CDM to create a Schtasks(Update in minute)
  Schtasks /create /tn "Firewall_Update" /RU SYSTEM /sc daily /st 00:00 /RI 1 /K /DU 24:00 /tr "C:\Windows\system32\firewall_update_win.exe ip.txt.example.com"