Colasoft Capsa 

Easy-to-use network monitor and protocol analyzer designed for packet decoding and network diagnosis, helping network administrators troubleshoot network problems.
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Acid Scanner 

Advanced scanning tool to audit your network. Includes many ip utilities in one program. Shared resource scan, ping, port scan, traceroute, terminal (tcp/udp) and much more... Incredibly fast due to its multithreading desing.
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