51.161.65.139📋 Copy

# IPDEBRIEF INTELLIGENCE BRIEFING

Target: 51.161.65.139/32

Classification: Moderate Risk (Score: 40/100)

Report Date: Current

Analyst: Automated Intelligence System

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## EXECUTIVE SUMMARY

IP 51.161.65.139 is a hosting infrastructure address owned by OVH SAS (ASN 16276) operating under the Ahrefs Pte Ltd organizational entity. The IP is hosted in Montreal, Quebec, Canada and resolves to ahrefs.net. Despite corporate domain association, the IP exhibits moderate risk characteristics with blacklist presence and operates within a high-abuse density subnet.

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## NETWORK IDENTIFICATION

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## THREAT ASSESSMENT

Risk Profile: Moderate Risk (Score: 40/100)

Threat Indicators:

• Blacklist Count: 1 (of 8 total DNSBL checks)
• Abuse Confidence Score: Not applicable
• Known Attacker: No
• Spam Source: No
• Tor Exit Node: No
• VPN/Proxy: No

Control Plane Data:

• Origin ASN: 16276
• BGP Prefix: 51.161.0.0/17
• Route Stability: False
• DNSSEC Valid: True
• DNSBL Listed: 1/8 lists

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## SUBNET ANALYSIS (51.161.65.0/24)

Abuse Density: 0.6094 (High Abuse Classification)

Subnet Statistics:

• Total Siblings: 256 IPs
• Active Siblings: 207
• Threat Siblings: 156
• Risk Distribution: 100 medium, 0 high, 0 low

Risk Context: The /24 subnet exhibits elevated abuse density with 156 identified threat siblings. This contextualizes the moderate risk score within a higher-risk network environment.

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## DNS & SERVICE ANALYSIS

Note: Services show as "Firewalled / No Services" – IP may be configured for non-public access or uses load balancing.

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## OBSERVATION HISTORY

Recent signals indicate consistent infrastructure characteristics:

• June 28, 2026: Listed on 1 blacklist (max severity: high)
• June 20, 2026: Geolocation confirmed (Canada), cloud hosting classification
• Stability: Ownership stable with zero changes recorded

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## RECOMMENDED ACTIONS

Blocking Recommendations:

• iptables: `iptables -A INPUT -s 51.161.65.139 -j DROP`
• nftables: `nft add rule inet filter input ip saddr 51.161.65.139 drop`
• nginx: `deny 51.161.65.139;`
• pfSense: Block 51.161.65.139/32
• Cloudflare WAF: Block rule with expression `ip.src eq 51.161.65.139`
• AWS WAF: Add 51.161.65.139/32 to blocklist

Operational Notes:

• Consider subnet-level monitoring due to high abuse density (0.6094)
• Blacklist presence suggests potential reputation concerns
• No active threat campaigns correlated

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## ANALYST RECOMMENDATION

Monitor this IP for 72 hours with traffic logging. The moderate risk score combined with high-abuse subnet context warrants observation, but immediate blocking may impact legitimate ahrefs.net operations. Implement rate limiting or allowlisting if business requirements for ahrefs.net services exist.

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