What it is
Response headers such as `Server`, `X-Powered-By`, `X-AspNet-Version`, `X-AspNetMvc-Version`, and `X-Generator` can announce the exact software, and often the precise version, running on your public edge.
Why it matters
Version detail lets an attacker match known vulnerabilities to your stack without any probing, turning broad scanning into a targeted shortlist. Suppressing or genericizing these banners removes that free reconnaissance. A banner that includes a version number is a stronger signal than a bare product name.
How WebGuard checks it
WebGuard reads your response headers and reports when `Server`, `X-Powered-By`, `X-AspNet(-Mvc)-Version`, or `X-Generator` expose product or version detail. It only inspects headers your public site already returns; it does not probe or fingerprint beyond that.
A sensible starting configuration:
Prefer a generic banner (e.g. `Server: nginx`) over one with a version (`Server: nginx/1.18.0`); remove X-Powered-By entirely.