This is a fake DNS server that allows you to stealthily extract files from a victim machine through DNS requests.
Below are a couple of different images showing examples of multiple file transfer and single verbose file transfer:

Support for multiple files
Gzip compression supported
Now supports the customisation of subdomains and bytes per subdomain and the length of filename
See help below:
https://github.com/m57/dnsteal

GitHub - m57/dnsteal: DNS Exfiltration tool for stealthily sending files over DNS requests.
DNS Exfiltration tool for stealthily sending files over DNS requests. - m57/dnsteal