Utility to generate the seeds.txt list that is compiled into the client (see src/chainparamsseeds.h and other utilities in contrib/seeds).
Be sure to update PATTERN_AGENT in makeseeds.py to include the current version,
and remove old versions as necessary.
The seeds compiled into the release are created from sipa's DNS seed data, like this:
curl -s http://bitcoin.sipa.be/seeds.txt.gz | gzip -dc > seeds_main.txt
python3 makeseeds.py < seeds_main.txt > nodes_main.txt
python3 generate-seeds.py . > ../../src/chainparamsseeds.h
Ubuntu:
sudo apt-get install python3-dnspython