Ubuntu

What is GNS3? GNS3 is used by hundreds of thousands of network engineers worldwide to emulate, configure, test and troubleshoot virtual and real networks. GNS3 allows you to run a small topology consisting of only a few devices on your laptop, to those that have many devices hosted on multiple servers or even hosted in the cloud. Architecture GNS3 consists of two software components the GNS3-all-in-one software GUI client and the server.

Nextcloud is a suite of client-server software for creating and using file hosting services. Nextcloud application functionally is similar to Dropbox.

Redmine is a free and open source, web-based project management and issue tracking tool. I will install it on Ubuntu becous on CetOS there in no pre build package for redmine.