Free Axence NetTools is a comprehensive set of host monitoring, network scanning, security & administration tools - all with a highly intuitive user interface:

- Port scanner - checks for all open ports and running services. It can discover some Trojans/spyware.

- Network scanner - discovers all nodes in a remote network, their IP/MAC and services running on them.

- NetStat - displays your computer's inbound and outbound connections, lists all open TCP/UDP ports, with the remote IP address & the process using the connection.

- TCP/IP workshop - establishes low-level TCP/UDP connections to troubleshoot and test network services. It can send raw data to any remote port.

- Other tools: fast traceroute shows information about every host on the route, its response time, and packets lost (full trace within 1 second). Lookup is like nslookup, but it shows you all DNS and WHOIS records at once. Bandwidth tool will measure network performance. NetCheck - with this tool you can check the quality of network hardware in your LAN.