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AbuseIPDB » 51.81.110.51

51.81.110.51 was found in our database!

This IP was reported 5,509 times. Confidence of Abuse is 0%: ?

ISP	OVH US LLC
Usage Type	Data Center/Web Hosting/Transit
ASN	AS16276
Hostname(s)	proxy-us-east004-cip4.ahrefs.net
Domain Name	ovhcloud.com
Country	🇺🇸 United States of America
City	Warrenton, Virginia

IP info including ISP, Usage Type, and Location provided by IPInfo. Updated weekly.

Important Note: 51.81.110.51 is an IP address from within our whitelist belonging to the subnet 51.81.110.48/28, which we identify as: "Ahrefs Crawler".

Whitelisted netblocks are typically owned by trusted entities, such as Google or Microsoft who may use them for search engine spiders. However, these same entities sometimes also provide cloud servers and mail services which are easily abused. Pay special attention when trusting or distrusting these IPs.

Report 51.81.110.51

Whois 51.81.110.51

IP Abuse Reports for 51.81.110.51:

This IP address has been reported a total of 5,509 times from 89 distinct sources. 51.81.110.51 was first reported on November 18th 2024, and the most recent report was 13 hours ago.

Recent Reports: We have received reports of abusive activity from this IP address within the last week. It is potentially still actively engaged in abusive activities.

Reporter	IoA Timestamp (UTC)	Comment	Categories
🇺🇸 SX Communications	2026-09-17 23:10:26 (13 hours ago)	Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this add ... show more Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this address continues high-cost dynamic page and feed requests at abusive rates via TCP/HTTPS despite edge block responses. Likely compromised end-user host. show less	DDoS Attack Bad Web Bot Exploited Host
🇩🇪 palzer.IT	2026-09-16 17:15:17 (1 day ago)	Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [13/Sep/2026:02:10:39 +0200] GET ... show more Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [13/Sep/2026:02:10:39 +0200] GET /sitemap_index.xml [DOMAIN_REMOVED] 200 5803 - Mozilla/5.0 (compatible; AhrefsBot/7.0; +[DOMAIN_REMOVED] show less	Bad Web Bot
🇺🇸 LotPhantom	2026-09-13 23:46:21 (4 days ago)	51.81.110.51 - - [13/Sep/2026:23:45:21 +0000] "GET / HTTP/2.0" 200 35207 "-" "Mozilla/5.0 (compatibl ... show more 51.81.110.51 - - [13/Sep/2026:23:45:21 +0000] "GET / HTTP/2.0" 200 35207 "-" "Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)" ... show less	Web App Attack Bad Web Bot
🇩🇪 palzer.IT	2026-09-13 00:10:57 (5 days ago)	Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [13/Sep/2026:02:10:39 +0200] GET ... show more Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [13/Sep/2026:02:10:39 +0200] GET /sitemap_index.xml [DOMAIN_REMOVED] 200 5803 - Mozilla/5.0 (compatible; AhrefsBot/7.0; +[DOMAIN_REMOVED] show less	Bad Web Bot
🇺🇸 SX Communications	2026-09-12 00:13:33 (6 days ago)	Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this add ... show more Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this address continues high-cost dynamic page and feed requests at abusive rates via TCP/HTTPS despite edge block responses. Likely compromised end-user host. show less	DDoS Attack Bad Web Bot Exploited Host
🇺🇸 TPI-Abuse	2026-09-09 11:34:18 (1 week ago)	(mod_security) mod_security (id:210730) triggered by 51.81.110.51 (proxy-us-east004-cip4.ahrefs.net) ... show more (mod_security) mod_security (id:210730) triggered by 51.81.110.51 (proxy-us-east004-cip4.ahrefs.net): 1 in the last 300 secs; Ports: *; Direction: 1; Trigger: LF_MODSEC; Logs: [Wed Sep 09 07:34:12.854539 2026] [security2:error] [pid 25359:tid 25359] [client 51.81.110.51:58012] ModSecurity: Access denied with code 403 (phase 2). Match of "pmFromFile userdata_wl_extensions" against "TX:extension" required. [file "/etc/apache2/conf.d/modsec_vendor_configs/comodo_apache/10_HTTP_HTTP.conf"] [line "27"] [id "210730"] [rev "5"] [msg "COMODO WAF: URL file extension is restricted by policy\|\|elcalamo.com\|F\|2"] [data ".pdb"] [severity "CRITICAL"] [tag "CWAF"] [tag "HTTP"] [hostname "elcalamo.com"] [uri "/pda/zurita-lvn.PDB"] [unique_id "aqFENDyzXndKwjtoh44u7QAAAAE"] show less	Brute-Force Bad Web Bot Web App Attack
🇨🇦 Mediashaker	2026-09-08 19:48:53 (1 week ago)	(apache-useragents) Failed apache-useragents trigger with match [redacted] from 51.81.110.51 (US/Uni ... show more (apache-useragents) Failed apache-useragents trigger with match [redacted] from 51.81.110.51 (US/United States/proxy-us-east004-cip4.ahrefs.net) show less	Bad Web Bot
🇩🇪 ghostwarriors	2026-09-08 00:50:09 (1 week ago)	Webpage scraping	Brute-Force Bad Web Bot Web App Attack
🇩🇪 palzer.IT	2026-09-07 20:08:09 (1 week ago)	Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [07/Sep/2026:22:07:54 +0200] GET ... show more Fail2ban automatic report for plesk-apache-badbot: 51.81.110.51 - - [07/Sep/2026:22:07:54 +0200] GET /robots.txt [DOMAIN_REMOVED] 200 5952 - Mozilla/5.0 (compatible; AhrefsBot/7.0; +[DOMAIN_REMOVED] show less	Bad Web Bot
Anonymous	2026-09-07 09:58:49 (1 week ago)	51.81.110.51 www.rolistore.com - [06/Sep/2026:17:32:56 -0600] "GET /ratones/mouse-logitech-m220-sile ... show more 51.81.110.51 www.rolistore.com - [06/Sep/2026:17:32:56 -0600] "GET /ratones/mouse-logitech-m220-silent-negro HTTP/1.1" 200 711262 "-" "Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)" 51.81.110.51 www.rolistore.com - [06/Sep/2026:17:33:45 -0600] "GET /cat-calcetines/calcetines-playstation-logo HTTP/1.1" 200 736106 "-" "Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)" 51.81.110.51 www.irwindalecycles.com - [07/Sep/2026:03:58:48 -0600] "GET /bikes/cat-bikes-bmx HTTP/1.1" 200 399378 "-" "Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)" ... show less	Bad Web Bot
🇫🇷 GabrielJST	2026-09-03 11:27:10 (2 weeks ago)	(apache-useragents) Failed apache-useragents trigger with match [redacted] from 51.81.110.51 (US/Uni ... show more (apache-useragents) Failed apache-useragents trigger with match [redacted] from 51.81.110.51 (US/United States/proxy-us-east004-cip4.ahrefs.net) show less	Bad Web Bot
🇩🇪 bescared	2026-09-01 13:22:55 (2 weeks ago)	F2B - Malicious activity detected. URL Probing. -8ff06ede-	Hacking Bad Web Bot Web App Attack
🇩🇪 Hazzard	2026-09-01 07:08:25 (2 weeks ago)	(apache-useragents) Failed apache-useragents trigger with match [redacted]): (CF_ENABLE)	Bad Web Bot
🇺🇸 SX Communications	2026-08-31 11:01:22 (2 weeks ago)	Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this add ... show more Blocked abusive HTTP application-layer DoS / botnet traffic from 51.81.110.51: traffic from this address continues high-cost dynamic page and feed requests at abusive rates via TCP/HTTPS despite edge block responses. Likely compromised end-user host. show less	DDoS Attack Bad Web Bot Exploited Host
🇬🇷 setupgr	2026-08-28 22:20:36 (2 weeks ago)	(mod_security) mod_security (id:11000010) triggered by 51.81.110.51 (US/United States/Virginia/Resto ... show more (mod_security) mod_security (id:11000010) triggered by 51.81.110.51 (US/United States/Virginia/Reston/-/[AS16276 OVH]): 1 in the last 86400 secs (CF_ENABLE); Ports: *; Direction: inout; Trigger: LF_MODSEC; Logs: [Sat Aug 29 01:20:33.282219 2026] [security2:error] [pid 156892:tid 156903] [remote 51.81.110.51:46690] ModSecurity: Access denied with code 403 (phase 1). Matched phrase "AhrefsBot" at REQUEST_HEADERS:User-Agent. [file "/etc/apache2/conf.d/modsec/modsec2.user.conf"] [line "114"] [id "11000010"] [msg "BLOCKED BOT: AhrefsBot on ftiaxtomonosou.gr"] [severity "ALERT"] [hostname "ftiaxtomonosou.gr"] [uri "/robots.txt"] [unique_id "apIJsSnzwn9qihpQGgOpDQAAFQk"] show less	Port Scan

Showing 1 to 15 of 5509 reports

Think this IP has been falsely reported? You may request to have the associated reports reviewed and removed. Request Takedown 🚩

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