RedTail iptables flush + high-port ACCEPT insertion with suspicious listener

Arnold Chan@slaz

•updated Sep 11, 2026•0•0•0

Detects a suspicious sequence of events on a Linux host: first, the 'iptables' firewall rules are flushed (-F), followed by the creation of an inbound TCP listener on a high port (>1024) and the activation of that port via iptables, finally correlating this with a network listener process residing in temporary or suspicious directories such as /tmp, /var/tmp, or /dev/shm. This behavior is indicative of a potential backdoor installation or temporary listener setup for unauthorized access.