The Port Scan Attack Detector (psad) is a collection of three system daemons that are designed to work with the Linux iptables firewalling code to detect port scans and other suspect traffic. It features a set of highly configurable danger thresholds (with sensible defaults), verbose alert messages, email alerting, DShield reporting, and automatic blocking of offending IP addresses. Psad incorporates many of the packet signatures included in Snort to detect various kinds of suspicious scans, and implements the same passive OS fingerprinting algorithm used by p0f.
Devil-Linux is a special secure Linux distribution which is used for firewalls, routers, gateways, and servers. The goal of Devil-Linux is to have a small, customizable, and secure Linux system. Configuration is saved on a floppy disk or USB stick, and it has several optional packages. Devil-Linux boots from CD, but can be stored on CF cards or USB sticks.
plugdaemon is a load-balancing "plug" proxy. It allows you to forward TCP connections to one or multiple hosts, using load balancing or failover, and to route the connections through an HTTPS proxy. Access control is done by source interface or by originating IP. Outgoing connections can be bound to a specific IP address.
eurephia is an authentication plug-in for OpenVPN. It enhances the OpenVPN authentication process by using user name and password authentication in addition to SSL certificates. If too many failed attempts are registered, the user account and/or IP address will be blocked. For Linux servers, iptables support is also included, which can be used to restrict each user's network access through the VPN channel. OpenVPN 2.2 or later is required.
libnfnetlink is a low-level userspace library for nfnetlink-based communication between the kernel-side netfilter and the user-space world. It is therefore the fundamental layer for all other nfnetlink-enabled user-space programs interfacing with the netfilter subsystem of the Linux kernel.
libnetfilter_cttimeout is an interface to Netfilter Connection Tracking timeouts. It provides a userspace library which provides a programming interface to the fine-grained connection tracking timeout infrastructure. With this library, you can create, update, and delete timeout policies which can be attached to traffic flows.