Tool which gives the graph of a network ?
(Like connections between routers ,hosts and servers )

Every router between you and another host: mtr, traceroute

Every host in your LAN (no switches): arp

Every host in a network range: nmap

I don't know of a tool that combines everything into one. But you can certainly build one using those tools I mentioned

Please be warned that scanning networks that aren't yours is mostly forbidden and can get your internet access blocked.

Nagios maybe?

zenmap :)

https://github.com/varchashva/...
There is a defcon talk about it.

Masscan perhaps?

Paint

@NoToJavaScript XD