51.161.37.213📋 Copy

## IP Intelligence Briefing: 51.161.37.213/32

Date: 2026-06-19

Classification: Moderate Risk – High-Abuse Subnet

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Executive Summary

IP address 51.161.37.213 is a cloud-hosted address registered to OVH's customer network (ASN 16276). While the IP itself shows no direct threat indicators, it resides within a subnet (51.161.37.0/24) with high abuse density (0.7422), where 190 of 206 active sibling IPs are flagged as threats. The address resolves to an Ahrefs-branded hostname but exhibits no active services.

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Network Profile

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Threat Assessment

• Direct Threat Indicators: None observed
• Blacklist Status: 0 direct listings
• Known Campaigns: None correlated
• Tor/Proxy/VPN: Negative (not classified as any proxy type)
• Abuse Confidence Score: Not applicable (no active threat signals)
• Threat Persistence: 0 days (no persistent malicious activity)

Subnet Context: The /24 subnet is classified as "high_abuse" with an inherited risk score of 29. Of 206 active sibling IPs, 190 are flagged as threats, indicating this is a high-density hosting environment.

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DNS & Hostname Analysis

• PTR Record: proxy-ca005-san213.ahrefs.net
• Forward Resolution: Unconfirmed
• Associated Domain: ahrefs.net
• Email Auth: SPF and DMARC records not configured
• DNSSEC: Valid
• CAA Records: Present

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Observed Services

No open ports detected. The IP shows as "Firewalled / No Services" with no TLS certificates or HTTP banner information. This is consistent with cloud infrastructure that may be behind additional network layers.

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Historical Observations

22 observations recorded, with the most recent on 2026-06-19. Key historical signals include:

• Operator score: 0.2174 (minimal risk classification)
• Subnet abuse density: 0.7422 (consistently high)
• Domain association: ahrefs.net
• Geolocation: Canada (with RTT validation anomalies)

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Recommended Security Actions

Due to the high-abuse subnet context and moderate risk profile, the following rules are recommended:

Firewall/IPS:

```bash

# iptables

iptables -A INPUT -s 51.161.37.213 -j DROP

# nftables

nft add rule inet filter input ip saddr 51.161.37.213 drop

# nginx

deny 51.161.37.213;

# pfSense

51.161.37.213/32

# Cloudflare WAF

{

"action": "block",

"description": "Block 51.161.37.213 — IPDebrief risk score 40",

"filter": {

"expression": "ip.src eq 51.161.37.213"

}

}

# AWS WAF

{

"Addresses": ["51.161.37.213/32"],

"Description": "IPDebrief risk 40"

}

```

Note: These recommendations are probabilistic and should be evaluated alongside other threat signals before enforcement. The subnet's high abuse density suggests consider implementing subnet-level blocking (51.161.37.0/24) if operational requirements permit.

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SOC Analyst Notes

• This IP represents legitimate cloud infrastructure (OVH hosting) with legitimate domain association (ahrefs.net)
• The primary concern is subnet-level abuse density rather than direct threat indicators
• Consider evaluating traffic patterns against baseline; no services currently exposed
• Monitor for changes in subnet classification or emergence of direct threat indicators
• Subnet blocking may be warranted if organizational policy tolerates potential collateral impact on legitimate traffic

This summary was generated by AI and may contain inaccuracies. Verify critical details independently.