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 (at a minimum when GetDesirableServiceFlags
changes its default return value, as those are the services which seeds are added
to addrman with).
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