51.161.37.255📋 Copy

INTELLIGENCE BRIEFING: IP 51.161.37.255/32

Classification: MODERATE RISK — Cloud Infrastructure with High-Abuse Neighborhood Context

Executive Summary

IP 51.161.37.255 is a cloud compute resource assigned to OVH SAS (AS16276) within the 51.161.37.0/24 subnet. The IP resolves to ahostname proxy-ca005-san255.ahrefs.net, indicating association with the Ahrefs organization (Dmytro, Ahrefs Pte Ltd). Current risk assessment rates this address as moderate risk (score: 40/100). However, the IP operates within a subnet exhibiting elevated abuse density (0.6562), with 168 of 256 active siblings flagged as threats.

Infrastructure Profile

• Network Classification: OVH cloud compute infrastructure
• ASN: AS16276 (OVH SAS)
• BGP Prefix: 51.161.0.0/17
• Geolocation: Montreal, Quebec, Canada (CA)
• Service Status: Firewalled/No Open Services Detected
• DNS Resolution: proxy-ca005-san255.ahrefs.net (ahrefs.net)
• Certificate/SSL: Not detected

Threat Assessment

• Risk Score: 40/100 (Moderate)
• Abuse Confidence: Not directly flagged as known attacker or spam source
• Tor Exit Node: No
• Known Campaigns: None identified
• Blacklist Status: 1 DNSBL listing detected (of 8 total threat feeds)
• Threat Persistence: 0 days (not persistently malicious)
• Route Stability: Unstable (isRouteStable: false)

Neighborhood Analysis

The /24 subnet (51.161.37.0/24) demonstrates elevated risk characteristics:

• Abuse Density: 0.6562 (High Abuse Classification)
• Active Siblings: 195 of 256 total IPs
• Threat Siblings: 168 flagged as threats
• Inherited Risk Score: 26 (from subnet context)

Sample neighbor risk distribution:

• 51.161.37.0 — Risk: 50, Authority: 50
• 51.161.37.1 — Risk: 40, Authority: 50
• 51.161.37.2 — Risk: 40, Authority: 50

Observation History

Recent signal observations (June 14, 2026 timeframe) indicate:

• Consistent cloud infrastructure classification
• Stable geographic attribution to Canada
• No significant escalation in threat indicators observed

Recommended Security Actions

Based on the moderate-risk profile and high-abuse neighborhood context, the following defensive measures are recommended:

Firewall Rules:

```bash

# iptables

iptables -A INPUT -s 51.161.37.255 -j DROP

# nftables

nft add rule inet filter input ip saddr 51.161.37.255 drop

# pfSense

51.161.37.255/32

```

WAF/Cloud Provider Integration:

• Cloudflare WAF: Block 51.161.37.255 (IPDebrief risk score 40)
• AWS WAF: Block 51.161.37.255/32 (Description: IPDebrief risk 40)
• nginx: deny 51.161.37.255;

Intel Note: While the IP itself lacks direct malicious indicators, the high-abuse neighborhood density warrants defensive blocking. The association with Ahrefs infrastructure may represent legitimate cloud usage, but the subnet-level abuse pattern suggests compromised co-located resources. Consider implementing subnet-level monitoring for 51.161.37.0/24 if this IP is blocked.

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