x11vnc allows one to remotely view and interact with real X displays (i.e. a display corresponding to a physical monitor, keyboard, and mouse) with any VNC viewer. It is designed to be compatible with all Unix variants and Mac OS X, and depends on a small set of standard libraries. It supports SSL/TLS and VeNCrypt encryption, Unix password logins, single port access, Zeroconf, file transfer, and UltraVNC extensions. It is part of the LibVNCServer project.
Moodss is a modular monitoring application, which supports operating systems (Linux, UNIX, Windows, etc.), databases (MySQL, Oracle, PostgreSQL, DB2, ODBC, etc.), networking (SNMP, Apache, etc.), and any device or process for which a module can be developed (in Tcl, Python, Perl, Java, and C). An intuitive GUI with full drag'n'drop support allows the construction of dashboards with graphs, pie charts, etc., while the thresholds functionality includes emails and user defined scripts. Monitored data can be archived in a SQL database by both the GUI and the companion daemon, so that complete history over time can be made available from Web pages or common spreadsheet software. It can even be used for future behavior prediction or capacity planning, from the included predictor tool, based on powerful statistical methods and artificial neural networks.
stresslinux is a minimal Linux distribution that runs from a bootable CDROM or via PXE. It makes use of some utitlities such as stress, cpuburn, hddtemp, lm_sensors, etc. It is dedicated to users who want to test their system(s) entirely on high load and monitor the health of these systems.
fwknop implements an authorization scheme called Single Packet Authorization that requires only a single encrypted packet to communicate various pieces of information, including desired access through an iptables, ipfw, or pf firewall policy and/or specific commands to execute on the target system. The main application of this program is to protect services such as SSH with an additional layer of security in order to make the exploitation of vulnerabilities much more difficult. The authorization server works by passively monitoring authorization packets via libpcap. Also supported is a robust port knocking implementation based around iptables log messages.
LFT (Layer Four Traceroute) is a sort of "traceroute" that often works much faster than the commonly-used Van Jacobson method and goes through many configurations of packet-filter based firewalls. More importantly, LFT implements numerous other features, including TCP, UDP, or ICMP-based traces, AS number lookups through several reliable sources, loose source routing, netblock name lookups, and more. LFT also distinguishes between layer-4 protocols, which make its statistics slightly more realistic, and gives a savvy user the ability to trace protocol routes, not just layer-3 hops.
Sshguard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. Sshguard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng, metalog, multilog, raw messages), and detects attacks for many services out of the box, including SSH, several ftpds, and dovecot. It can operate all the major firewalling systems, and features support for IPv6, whitelisting, suspension, and log message authentication.
dstat is a versatile replacement for vmstat, iostat, netstat, nfsstat, and ifstat. It includes various counters (in separate plugins) and allows you to select and view all of your system resources instantly; you can, for example, compare disk usage in combination with interrupts from your IDE controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval).
MoSShE (MOnitoring in Simple SHell Environment) is a simple, lightweight (both in size and system requirements) server monitoring package designed for secure and in-depth monitoring of a handful of typical/critical Internet systems. It supports email alerts and SLA monitoring out of the box, and whatever you can script. The system is programmed in plain (Bourne) SH, and made to be compatible with BASH and Busybox so it can easily be deployed on embedded systems. Monitoring is designed to be distributed over multiple systems, usually running locally. As no parameters are accepted from the outside, checks cannot be tampered or misused from outside. The system is designed to allow decentralized checks and evaluation as well as classical agent-based checks with centralized data accumulation. Agent data is transferred via HTTP, so available Web servers can be co-used for agent data transfer. Each agent creates simple (static) HTML pages with full and condensed status reports on each system, allowing simple local checks.
Elastix is a software appliance that integrates the best tools available for Asterisk-based PBXs into a single, easy-to-use interface. It also adds its own set of utilities and allows for the creation of third party modules. The goals of Elastix are reliability, modularity, and ease-of-use. It also features strong reporting capabilities.
Heartbeat is a full-function high-availability system for Linux and other POSIX-like OSes. It monitors services and restarts them on errors. When managing a cluster (more than 1 machine), it will also monitor the members of the cluster and begin recovery of lost services in less than a second. It runs over serial ports and UDP broadcast/multicast, as well as OpenAIS multicast. It is easily adapted to different interconnect media and protocols. When used in a cluster, it can operate using shared disks, data replication, or no data sharing. Versions starting with 2.0 are comparable to any commercial HA package, providing resource monitoring, larger clusters, and detailed dependency information.