Andrisoft WANGUARD is an enterprise-grade traffic monitoring and DDoS detection and protection solution that delivers the functionality NOC, IT, and security teams need to effectively monitor and protect their network through a single, integrated package. WANGUARD Sensor relies on sFlow, NetFlow, IPFIX, or Port Mirroring / SPAN.
SpamBlock counts attempts to establish a connection on port 25/tcp via tcpdump. When a host exceeds the allowed number of attempts per unit of time, it is added to a corresponding ipfw table and email notification is sent. Spamblock currently supports ipfw only, but it can be easily adapted for any firewall and OS. It can also be configured to watch multiple ports to prevent Telnet and SSH attacks in addition to SMTP.