LogError writes: "Sniffers are tools, also known as network analyzers, used for monitoring network traffic. As such, if used by authorized personnel, can prove to be of a great value. But, on the other hand, sniffers represent significant threat to your network, and are very hard to detect.
"Why a threat, one might wonder? Sniffers do not pose as a direct threat to your data in the common sense of the word, like viruses or malicious code. No, the threat lies in the fact that sniffers are network analyzers designed to monitor network traffic. A high level of risk lies within the abuse of sniffers, due to the fact that an attacker, or a hostile user can gather information that travels through the network, sensitive information like passwords, various confidential information and similiar, stored in plain text or other formats. Usually, the presence of a sniffer on the network can indicate future, more serious attacks against the network. Information gathered through the usage of sniffers can be used for upcoming attacks, further network compromises and can lead to a complete data disclosure and network compromise. So, it's of a great value to recognise the risks posed by network sniffers.
The entire article is located at Help Net Security."