Reconnaissance
Network reconnaissance (scanning)
Attackers map what is listening on a network. Defenders watch for unusual scan patterns so they can investigate before exploitation starts.
If you are new — start here
- Reconnaissance is the “looking around” stage — finding hosts, ports, and services.
- It is not itself a break-in, but it often comes right before one.
- Your job: know which scans are expected (approved assessment, vulnerability scanner) and which are not.
- Start by answering: who scanned, from where, what targets, and was it in change/approval records?
What it looks like
- Many connection attempts from one source to many ports or many hosts in a short window
- Firewall / IDS alerts for port sweeps or unusual protocol probes
- VPN or jump-box traffic probing internal ranges outside normal admin behaviour
Defender response
- Confirm whether the source is an approved scanner or engagement
- Preserve firewall / IDS / NetFlow evidence with timestamps
- If unapproved: contain the source host or account, then investigate for follow-on activity