Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Abusix - Abusix is a network security company that offers email threat protection and network abuse handling solutions to ISPs, Telcos, and Cloud/Hosting Providers to stop the rapidly growing problem of email-borne threats and other kinds of network abuse.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
NetVizura NetFlow Analyzer - NetFlow Analyzer is a solution for bandwidth monitoring and traffic analysis. It helps with traffic investigation, analysis and reporting
Omnipeek - Omnipeek is a packet analyzer software tool from Savvius that allows network troubleshooting and protocol analysis and enables decoding thousands of protocols for fast network troubleshooting and diagnostics for anywhere network issues.
Observium - Observium