Nagios (1.4k ⭐) is an open-source monitoring and alerting system. It can monitor many services such as SSH, FTP, SMTP, and so on.

  • The version is shown at the bottom after being logged
  • The endpoint /about may help in determining the version
  • Default credentials are: nagiosadmin:PASSW0RD

Nagios can be extended through the use of plugins.