alert dns $HOME_NET any -> any any (msg:"ET INFO Observed DNS Query to DynDNS Domain (linkpc .net)"; dns.query; content:".linkpc.net"; nocase; endswith; content:!"www.linkpc.net"; reference:url,dnsexit.com/domains/free-second-level-domains/; classtype:bad-unknown; sid:2034458; rev:3; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2021_11_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, updated_at 2022_06_08;)