I would like to make some simple network simulations
I've tried to make run few (under Linux or Windows)
Kathara
GNS3
EVE-NG (3.1 GB ! to download )
omnetpp
ns-3
Cisco Packet Tracer (Not FLOSS, if I'm not mistaken )
The only one that I managed to install, run and use (set some nodes) was sadly the Cisco Packet Tracer ...
They other have their install process way to much complex or with such layer of dependency or more simply they way the works is too complex (running side VM for each nodes etc..) make it challenging to installing.
Do youn know a FLOSS Network Simulator , this is easy to install ?
Packet tracer is definitely not OSS nor free as in speech. But it is probably your best bet for something to get started with. You can go on netacad and get it for free together with the self-paced introduction to packet tracer course. I'm not trying to shrill for Cisco, they're a soulless company that exploits their position to extort insane prices. But PT is kinda nice, IF! all you want is to build simple networks and you don't care about being vendor agnostic or only running FOSS.
PS: and cisco? 2900€ for a 24port l3 switch? GTFO, a mikrotik crs326 can do the same and is 200€ and it doesn't require a DNA-center to enable licensing, why? BECAUSE IT DOESN'T REQUIRE ADDITIONAL LICENSES!!1!one!
Depending on your use case, you can pretty far with just docker and some Linux packages. I've done GRE, BGP, OSPF, ISIS, Open vSwitch. That's Linux networking though. If you're trying to prep for a specific vendor's cert, it might not meet your needs.
I only used GNS3 and Cisco Packet Tracer from the list when self-teaching CCNA. GNS3 installation shouldn't be that hard. On Windows just use the installation and fire up a VM in VBOX / HyperV (recommended) and it should automatically detect it. On Linux I have installed GNS3 using AUR package in ArchLinux, haven't tried on Ubuntu, but it should be straight forward. For the VM, you will need hypervisor setup (virt-manager, libvirtd) and KVM enabled. Most of the distrobutions should have its own kvm virtualization guide. You can also skip GNS3 installation on the host and just go to IP of the VM,so you can use beta Web UI where you can do most of the things you can do in GNS3 app. Good luck!