I couldn't find answers to this question on this forum so I'm just gonna ask:

What are Active Scans and Passive Scans? What are their differences?

Please include in your answer(s):

  • differences in methods
  • risks in using active/passive scanners
  • how stealthy they usually are
  • what they are usually used for and how to choose between the two
  • 5
    This looks like a homework which the OP is forwarding here. Even if it is not: there are plenty of information on the internet which can be easily found by using a search engine. It can be expected that the OP does such initial research first and then asks a more focused question about the parts he did not found or where he is unsure about the answers. But don't expect that the answer to all the different points will be found in a single place or can be found with a single search because this is a broad question. Oct 8, 2019 at 5:21
  • I actually did look into the definition. I'd just like to learn more about the risks in using active scanning and when to use which from more experienced people, as well as (hopefully) putting answers useful to beginners (such as myself) on the site. Oct 8, 2019 at 12:46
  • 3
    "I actually did look into the definition" - You've explicitly asked for definition and differences which suggests that you did not look into these so far or found nothing. If you did you would either understand these definitions or you could explain what you've found so far and what you did not understand. Oct 8, 2019 at 12:59
  • Sorry about that. What I'm mainly looking for is suggestions on how to choose and use the scans. The "definition" was supposed to be for extra clarity, but I supposed it was unnecessary. Oct 9, 2019 at 2:25

1 Answer 1


If you are interacting with the target you call it an "active scan". If you don't, you call it a "passive scan".

If you are interacting with the target, there is more of a chance to get caught by IDS/IPS systems. The passive scan is stealthy because of this.

The common methodology is doing a passive scan first and then doing active scans.

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