PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Zabbix - Track, record, alert and visualize performance and availability of IT resources
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Komodia Relay - Free open source tool to perform TCP based session relay
Prometheus - An open-source systems monitoring and alerting toolkit.