Postfix 451 4.7.0: Distinguish Remote SMTP Outages from Local Queue Issues
When recipients at a major mail provider begin returning 451 4.7.0 Temporary server error, the correct first response is usually observation, not aggressive…
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RISORSA IN EVIDENZA
BAD crawler / scraper ip address blacklist
Blacklist di indirizzi IP legati a crawler e scraper indesiderati: un riferimento tecnico per analizzare e gestire il traffico automatico.
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Guide, comandi e soluzioni dal diario tecnico
Why CrowdSec Bans Reappear After cscli decisions delete
Removing a CrowdSec decision does not guarantee that the IP will remain unblocked. If the same client keeps generating matching access-log events, a…
Leggi l'articoloApache Reverse Proxy: Prevent GeoIP Bypass via X-Forwarded-For
GeoIP restrictions in Apache can fail when a reverse proxy trusts client-supplied forwarding headers. An attacker who controls X-Forwarded-For may be able to…
Leggi l'articoloPostfix: Diagnose IPv6 Network Unreachable When Sending to Microsoft 365
Mail can remain in Postfix’s deferred queue when outbound SMTP tries an IPv6 address that the host cannot route. The typical diagnostic is…
Leggi l'articoloDetect curl, wget and Automated HTTP Clients with CrowdSec
Automated HTTP clients often identify themselves as curl/, Wget/, python-requests/ or Go-http-client/. These signatures can be useful on a public site that has…
Leggi l'articoloPrevent CrowdSec from Blocking Verified AI Crawlers
A crawler can be genuine and still trigger an over-aggressive security rule. A legitimate search bot may request a missing URL without a…
Leggi l'articoloCrowdSec and ipset: Increase maxelem Without Losing Active Bans
Large CrowdSec deployments can fill an ipset long before the host runs out of RAM. The kernel set may show hundreds of thousands…
Leggi l'articoloPublish a CrowdSec IP Blacklist with RRDtool Graphs and a Color-Coded World Map
A public IP blacklist is much more useful when it is automatically refreshed, auditable, and accompanied by a trend graph and a geographic…
Leggi l'articoloModSecurity: bloccare PHP_SESSION_UPLOAD_PROGRESS come mitigazione temporanea
Mitigazione d'emergenza per upload progress in PHP con controlli di caricamento e test dei servizi Apache/PHP-FPM.
Leggi l'articoloSpamAssassin: creare una regola locale che aumenti il punteggio solo per certi destinatari
Regola antispam locale applicata per combinare dominio del mittente e dominio del destinatario senza penalizzare tutta la posta in ingresso.
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