27019
MongoDB config server storing sharding metadata
MongoDB Config Server
What is port 27019?
Port 27019 is used by MongoDB config servers, which store the metadata and routing information for sharded clusters — including the mapping of data ranges to shard servers. Config servers are critical to the operation of a sharded cluster and must be completely isolated from the internet.
Quick checks
$
nc -zv example.com 27019
$
nmap -p 27019 example.com
$
telnet example.com 27019