dns-filter

dns-filter is your custom forwarding DNS server that redirects input traffic matching given regular expression to another host.

Usage:

python3 dns_filter.py --verbose --port 10053 --cname xyz.net --ns1 ns1.example.com. --ns2 ns2.example.com. --regexp "^abcd.+?.com$"

Options:

-h, --help            show this help message and exit
-v, --verbose         log incoming requests to the console
-p PORT, --port=PORT  DNS server port number
-t CNAME, --cname=CNAME        destination CNAME
--ns1=NAMESERVER1        destination NAMESERVER1
--ns2=NAMESERVER2       destination NAMESERVER2
-r REGEXP, --regexp=REGEXP
                      regular expression to be checked
-i INTERFACE, --interface=INTERFACE
                      interface IP to listen on

Example:

Install Twisted library first:

$ python3 -m pip install twisted

Run dns-filter server locally:

$ python3 dns_filter.py --verbose --port 10053 --cname xyz.net --ns1 ns1.example.com. --ns2 ns2.example.com. --regexp "^abcd.+?.com$"

Open another console window and run test request via system dig tool:

$ dig -p 10053 @localhost abcd-example.com CNAME +short
xyz.net

Based on: https://twistedmatrix.com/documents/16.5.0/names/howto/custom-server.html