Greynoise

GreyNoise — Internet Scanner Intelligence

GreyNoise collects and analyses internet-wide scan traffic. It tells you whether an IP hitting your firewall is a known mass-scanner (benign research tool or malicious crawler) versus a targeted attacker — helping SOC teams filter out internet noise from real threats.

Community tier: The /v3/community/{ip} endpoint works with limited volume even without a key. Set GREYNOISE_API_KEY for higher rate limits.

When to Use

• An IP triggers a firewall rule and you want to know if it is just background internet noise
• SOC triage: is this alert a known scanner or a targeted attack?
• Filter false positives from SIEM before escalating an alert
• User asks "is this IP a scanner?", "is this noisy traffic?", "is IP X benign?"

How to Use

Check if an IP is a known internet scanner

$ip      = "71.6.135.131"
$headers = @{}
if ($env:GREYNOISE_API_KEY) { $headers['key'] = $env:GREYNOISE_API_KEY }

$result = Invoke-RestMethod -Uri "https://api.greynoise.io/v3/community/$ip" -Headers $headers
Write-Host "IP:             $($result.ip)"
Write-Host "Noise:          $($result.noise)"        # true = mass-scanner
Write-Host "RIOT:           $($result.riot)"         # true = trusted benign service
Write-Host "Classification: $($result.classification)"  # benign | malicious | unknown
Write-Host "Name:           $($result.name)"
Write-Host "Last seen:      $($result.last_seen)"
Write-Host "Link:           $($result.link)"
Write-Host "Message:        $($result.message)"

Triage a batch of IPs from a firewall log

$ips = @("1.1.1.1", "8.8.8.8", "71.6.135.131", "45.83.66.42")
$headers = @{}
if ($env:GREYNOISE_API_KEY) { $headers['key'] = $env:GREYNOISE_API_KEY }

foreach ($ip in $ips) {
    try {
        $r = Invoke-RestMethod -Uri "https://api.greynoise.io/v3/community/$ip" -Headers $headers
        $tag = if ($r.riot) { '[RIOT-trusted]' } elseif ($r.noise) { '[SCANNER]' } else { '[TARGETED?]' }
        Write-Host "$ip  $tag  $($r.classification)  $($r.name)"
    } catch {
        Write-Host "$ip  [ERROR]  $($_.Exception.Message)"
    }
    Start-Sleep -Milliseconds 200
}

Interpret the results

noise = true   → IP is a known mass-scanner (benign researchers, crawlers, etc.)
riot  = true   → IP belongs to a trusted service (Cloudflare, Google, AWS, etc.)
classification = "malicious"  → Known malicious scanner — block and investigate
classification = "benign"     → Probably safe background noise — may deprioritise
classification = "unknown"    → No data — treat with caution

Examples

"Is 71.6.135.131 an attacker?" → Returns classification: malicious, noise: true — known malicious scanner.

"This IP keeps hitting our web server — is it just background noise?" → noise: true means it is scanning the whole internet, not targeting you specifically.

"Is 8.8.8.8 a threat?" → riot: true — belongs to Google DNS, trusted RIOT (Rule It Out) list.

Cautions

• Community endpoint returns limited data — GREYNOISE_API_KEY unlocks full context
• noise: false and riot: false does not mean the IP is malicious — GreyNoise may simply have no data for it
• Data reflects GreyNoise's scanner observations — gaps exist for low-volume IPs
• Free community endpoint: ~50 lookups/day per source IP without a key

Requirements

• No key required for low-volume community lookups
• GREYNOISE_API_KEY — free community key at https://viz.greynoise.io/account