# Install a lookup tool (Ubuntu/Debian) apt install whois whois 8.8.8.8 | grep -i origin
Since "ASN" can refer to several technical concepts (Autonomous System Number, Application Service Node, or an education provider like ASN), this article covers the most common and technically relevant scenarios for IT administrators and engineers. In the world of email server management, particularly for administrators handling Zimbra Collaboration Suite (ZCS) , logs and headers often present cryptic acronyms. One such term that frequently appears in mail logs, firewall rules, or anti-spam configurations is ASN . asn zimbra
Edit /opt/zimbra/common/conf/postfix_asn_blacklist Add the ASN netblocks (you must expand ASN to CIDR ranges manually or via script): # Install a lookup tool (Ubuntu/Debian) apt install
postmap /opt/zimbra/common/conf/postfix_asn_blacklist Application Service Node