Networkminer is a great Packet Analyzer that is great for monitoring the Security of your network. One of its strongest points is the ability to sniff and deliver data about the hosts instead of only basic packet information. Its user interface is very intuitive and easy to use thus making a network administrator jobs easier to analyze the data at hand. Another unique feature that deserves attention is its ability to reassemble the files transmitted through your network and having the ability to download them - Awesome! Let's get to the download info.
NetworkMiner comes in two versions. There is a free version and then you have a professional edition that cost $700 USD. While there are much more features offered in the professional edition, the free edition is great to get your feet wet. If you are larger enterprise and you need a serious machine, then the paid version is the way to go. As always, we promote trial before pay. Happy Analyzing!