Common Linux network tools

ping
ping -f google.com # test your network functionality
ping -f -s 4096 ubuntu # ping flood

netstat -tulpen # everything that it is listening on this computer

ss #socket stats alternative to netstat
ss -tuna

nmap # very rich network scanner
nmap 192.168.4.2
name localhost

dig # it is about DNS, allows you to test functionality of your DNS server
dig nu.nl