27017
MongoDB NoSQL document database
MongoDB Database
What is port 27017?
Port 27017 is the default port for MongoDB, one of the most popular NoSQL document databases. It is widely used in Node.js, Python, and cloud-native applications. MongoDB originally shipped without authentication enabled by default, leading to the 2017 "MongoDB Apocalypse" in which thousands of exposed databases were wiped and held for ransom. Always enable authentication, bind to localhost, and use a firewall.
Quick checks
$
nc -zv example.com 27017
$
nmap -p 27017 example.com
$
telnet example.com 27017