Open Source denotes to some program whose source code is made available for usage

It is used to help the user or administrator for fixed errors.

Open NMS (Network Management System) is a free and open-source initiative grade network monitoring and management platform. It is established and maintained by a community of users developers and by the open NMS group, it offering services, training and support.

NS2 is the abbreviation of NETWORK SIMULATOR version 2. It was considered explicitly for exploration in network communication and event-driven open-source simulator in computer.

A network simulator is a software program that replicates the functioning of a computer network.In simulators, the computer network is typically demonstrated with devices, traffic etc. and the performance are evaluated.

OSS projects are collaboration opportunities that improve skills and build connections in the field.
Domains that developers can contribute to the open source community include:
(i) Communication tools.
(ii) Distributed revision control systems.
(iii) Bug trackers and task lists.
(iv) Testing and debugging tools.

(i) Remix
(ii) Remake
(iii) Remanufacture
(iv) Redistribute
(v) Resell
(vi) Study and Learn

Open NMS has three main functional areas:
(i) Services monitoring
(ii) Data Gathering
(iii) Event Management and notification
(i) Services monitoring:
A number of monitor modules can govern if network-based services are accessible (ICMP, HTTP, DNS, etc.).
(ii) Data Gathering:
Data Gathering by SNMP and JMX (Simple Network Management Protocol-SNMP, Java Management Extensions-JMX).
(iii) Event Management and notification:
It comprises of alarm reduction and a robust announcement system with acceleration and duty schedules.

(i) In this period of increased competition and cyber crimes, the computers used by indivudals or business organisations may have spy hardwares of rivals.
(ii) Open source hardware technology helps in such threats.
(iii) In this technique we get the components of the hardware and its circuit diagram, so that we can remove suspicious spyware if found.

(i) Free software is a concept developed in the 1980s by an MIT computer science researcher, Richard Stallman who defined four conditions, as outlined by the nonprofit Free Software Foundation.
(ii) These "four freedoms" emphasize the ability of users to use and enjoy software as they see fit.
(iii) Freeware usually refers to proprietary software that users can download at no cost, but whose source code cannot be changed.

(i) Open NMS (Network Management System) is a free and open-source initiative grade network monitoring and management platform.
(ii) It is established and maintained by a community of users, developers and by the Open NMS Group.
(iii) It offering services, training, and support.
The goal is for Open NMS
(i) The goal is for Open NMS to be an actually distributed, scalable management application platform for all features of the FCAPS (Fault, Configuration, Accounting, Performance, Security) network management model.
(ii) Presently the emphasis is on Fault and Performance Management.
It was intended to cope tens of thousands of devices from a single server as well as achieve unlimited devices using a cluster of servers.
Features:
(i) OpenNMS comprises a discovery engine to routinely configure and manage network devices without operator intervention. It is written in Java and is issued under the GNU (General Public License.)
(ii) OpenNMS is the World's first software for Network monitor and management with opensource options.
OpenNMS- Types:
There are two types in this Meridian and Horizon.
Meridian: When we need stability and long term support choose Meridian which is best for Enterprises as well as businesses.
Horizon:
(i) It is used where innovation occurs frequently.
(ii) It is Best for IT-ecosystem, new technology monitoring.
History:
(i) OpenNMS was Released in 1999 by Steve Giles, Brian Weaver, and Luke Rindfuss.
(ii) In 2004 OpenNMS Group was created by Balog, Matt Brozowski, and David Hustace.
(iii) It is written in Java and can run on all type of platform.
(iv) It gives us Event management & Notification, Discovery & Provisioning, service monitoring, and Data Collection.
(v) Won a lot of awards for best of opensource software.

OSS projects are collaboration opportunities that improve skills and build connections in the field.
Domains that developers can contribute to the open source community include:
1. Communication tools.
2. Distributed revision control systems.
3. Bug trackers and task lists.
4. Testing and debugging tools.
(i) There are many open source softwares. So, we can select and use any software that suits our needs.
(ii) The complete options of the software can be used without any cost and restrictions.
(iii) We can share our ideas with the team. write the required code and share it with many.
(iv) As we can identify the programming techniques of group members, we can learn many ideas and make our program writing skills more efficient.
(v) The coding in open source software are being groomed by many enthusiastical members of the groups. So, if we report problems that we have in the program they are quickly mended by the group's effort.
(vi) As we can make changes to the open source software, we can add the most required features in the software.
(vii) Many open source software are very user friendly.