- ping - Personal InterNetwork Groper. The tool will tell you whether or not a host is reachable on the network.
- Telnet - 'Teletype network' goes way back to 1969. Not very secure, but damn, is it useful. This will open a remote terminal session on a host (router, switch, firewall, server, etc.) using TCP.
- TFTP - Trivial File Transfer Protocol. A file transfer protocol using UDP. SAY WHAAAA?! Yes, I use it very often to this day. SolarWinds makes a nice server for Windows.
- SSH - Secure SHell is used to create a remote or local shell to a terminal. I like PuTTY in Windows, as it supports serial, telnet, and ssh in one program.
- traceroute / tracert - A tool used to trace a route to a destination. The methodology used to do so involves sending ICMP packets to each 'hop' or router along the path to the destination. This often (depending on the kindness of operators of networks along your path) will give you 'breadcrumbs' at each router along your path.
- arp - A command line tool that uses Address Resolution Protocol (see below) to display the MAC Address/IP Address table of connected devices. All OSs have this. - Thank you Mr. Troup!!! How could I forget this critical tool?!?! Takes one to know one?
- netstat - Tool to show what your current environment is connected to on the network. netstat is built into most operating systems.
- ntop - command line tool to show you the top used network resources in your environment. The creator has gone above just having a command line tool these days and has wrapped a webpage and analysis package around the tool. Worth checking out.
- ps - 'Process Status' command line tool to show you which processes are running in your environment.
- lsof - 'List Open Files' command line tool to show you which files are actively open in your environment.
- nmap - Multifunctional internetwork host identification and services discovery tool
- Wireshark - Want to 'hear what's on the wire?' Packet sniffer and analyzer that can be used to generate and inspect packet capture files (.pcap). It can be used on any network interface.
- iNet Network Scanner - Nice tool on Mac OS X for network discovery.
- iperf - Network packet generator... yes, it creates real traffic on your link/network. Use with caution in production environments!
- tcpdump/libpcap - network traffic (packet) analyzer and packet capture libraries used in tools like WireShark and nmap.
- nessus - Great network security scanning tool.
- ARP - Address Resolution Protocol
- CDP - Cisco Discovery Protocol
- LLDP - Link Layer Discovery Protocol - more standard version of CDP.
- SNMP - Simple Network Management Protocol
- NetFlow - Uses a '5-tuple' or '9-tuple' of data to analyze network traffic and how it flows through a specific link/network. Very useful in network analysis if done well.
- Notepad++ - plaintext heaven in Windows.
- Blinky - plaintext 'la petite mort' in OS X.
- Microsoft Visio - Standard in flowchart/network diagraming.
- OmniGraffle - Mac OS X flowchart software compatible with Visio formats.
- PRTG - Paessler Group's network and systems management suite. Can use ping, SNMP, and NetFlow in their 'sensors.' Really great tool to use to get to know your network better.
- SolarWinds Orion - A fairly standard network management suite, similar to PRTG, but sold in modules and is expensive. Very useful and good when tuned well.
- AirWave - Despite being owned/integrated with Aruba/HPE, AirWave still stands as a good network management platform for all vendors on its own.
- RANCID - Really Awesome New Cisco confIg Differ - open source configuration management for Cisco devices
- Cacti - Nice network graphs based on RRDTool using Apache/PHP/MySQL (AMP) stack.
- Nagios - Open source network monitoring project with paid option for support.
- Ansible - Automate your network!
- OpenNMS - Another open source network management suite with a paid version for support. Not used in production.
- LibreNMS - Another open source network management suite with a paid version for support. Not used in production.
- NetXMS - Another open source network management suite with a paid version for support. Not used in production.
- Zabbix - Another open source network management suite with a paid version for support. Not used in production.
- Zenoss - Another open source network management suite with a paid version for support. Not used in production.
- NetScout - Paid network monitoring platform. Not used in production.
- NetBrain - A 'hybrid' paid network suite that can monitor traditional, software defined networks (SDNs,) and cloud networks. Not used in production.
- NetCrunch - Paid network monitoring platform. Not used in production.
