logstash - logstash is a tool for managing events and logs.
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.
rsyslog - Rsyslog is an enhanced syslogd supporting, among others, MySQL, PostgreSQL, failover log...
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Graylog - Graylog is an open source log management platform for collecting, indexing, and analyzing both structured and unstructured data.
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.