AIDE (Advanced Intrusion Detection Environment) is a file and directory integrity checker. It creates a database from the regular expression rules that it finds from the config file. Once this database is initialized it can be used to verify the integrity of the files. Several message digest algorithms are used. All of the usual file attributes can also be checked for inconsistencies.
Angel is a simple yet useful tool to monitor the services on your network. Technically speaking, it's a Perl program that runs every 'n' minutes (usually fired from your cron) and calls different perl subprograms (referred to as "plugins" from now on) to do the actual testing. It will then generate an HTML table containing the status of your network.
Angst is an active sniffer, based on libpcap and libnet. It dumps into a file the payload of all the TCP packets received on the specified ports. It implements two methods for active sniffing. Angst is able to monitor ARP requests, and after enabling IP forwarding on the local host, it sends ARP replies mapping all IPs to the local MAC address. Also, it can flood the local network with random MAC addresses (like macof), causing switches to send packets to all ports.
Anteater is a log analyser for MTA logfiles (such as those produced by sendmail and postfix). The tool is written in 100% C++ and is very easy to customize. Input, output, and the analysis are modular class objects with a clear interface. Currently, there are modules for reading the syslog format of sendmail and postfix that do up to eight useful analyses and write the result in plain ASCII or HTML, to stdout or to files.
Aps is a small tool for analyzing network traffic. It prints out a great deal of information about the relevant protocols including TCP, UDP, ARP, and ICMP. It allows you to filter IP addresses, hardware addresses, ports, and specific protocols. It comes with a little GTK-GUI displaying packet counters for each protocol.
asapm is an AfterStep look & feel Advanced Power Management (APM) monitor for laptop and notebook PCs running Linux or FreeBSD/NetBSD/OpenBSD and X Windows. It displays charge left in the battery, the time left to the total discharge of the battery, computer is connected to the mains or is working on a battery and the battery status high/low/critical.
Automatos provides tools for automated performance analysis, capacity planning, and real-time monitoring of services across multiple platforms (Linux, NT/2000/XP, AIX, Solaris, Tru64, and HP-UX). The performance analysis service assists in identification or prevention of problems with computers within a company's network. The capacity wizard provides hardware upgrade planning support, suggestions being based on current (or simulated) growth rate. Real-time monitoring allows users to remotely monitor their machines from either a Web or a WAP console, generating notifications based on user-defined thresholds. Automatos is a low-intrusion system that uses strong encryption and compresses data for optimal and minimum bandwidth usage. Reports are generated in PDF format in several different languages. Ad-hoc online report generation and customization is also available.
autostatus is yet another network monitoring program. It was designed to be easy to use and configure, fast and efficient. The 'fast' and 'efficient' part is handled by making autostatus aware of network hierarchies, and avoiding checking a host or service when another host/service/link upon which it is dependent is unavailable. It exploits maximum parallelism during its checking to speed up monitoring.