Networking cheat sheet

nmcli device status                     # devices and their statenmcli connection show                   # saved connectionsnmcli connection show lab               # every setting of one connectionnmcli connection up lab                 # activate itnmcli connection down lab               # deactivate itnmcli connection delete lab             # remove itnmcli general hostname server1.example.com    # set the hostname

nmcli connection add type ethernet ifname eth0 con-name lab \  ipv4.method manual ipv4.addresses 192.168.1.10/24 \  ipv4.gateway 192.168.1.1 ipv4.dns 192.168.1.1nmcli connection modify lab ipv4.dns "1.1.1.1 8.8.8.8"     # change DNSnmcli connection modify lab +ipv4.addresses 192.168.1.11/24    # add a second addressnmcli connection modify lab ipv4.method auto ipv4.addresses "" ipv4.gateway ""    # back to DHCPnmcli connection up lab                                    # apply the change

ip addr show                  # addressesip -br a                      # short, readable formip link set eth0 up           # bring an interface upip route                      # routing tableip route get 8.8.8.8          # which route would be usedss -tulpn                     # listening ports with their processesping -c 3 host                # reachabilitytracepath host                # the path to a hostdig example.com               # DNS lookup (bind-utils)curl -I https://example.com   # HTTP headers onlync -zv host 22                # is a port open? (nmap-ncat)

hostnamectl                                   # show the hostname and OShostnamectl set-hostname server1.example.com  # set it permanentlycat /etc/resolv.conf                          # DNS servers in usecat /etc/hosts                                # static name mappings

firewall-cmd --state                              # is it running?firewall-cmd --get-default-zone                   # default zonefirewall-cmd --get-active-zones                   # zones in usefirewall-cmd --list-all                           # rules of the active zonefirewall-cmd --get-services                       # known service namesfirewall-cmd --add-service=http                   # runtime onlyfirewall-cmd --permanent --add-service=http       # saved, active after a reloadfirewall-cmd --permanent --add-port=8080/tcp      # open a portfirewall-cmd --permanent --remove-service=http    # close a servicefirewall-cmd --reload                             # load the permanent rulesfirewall-cmd --runtime-to-permanent               # save what is active now

firewall-cmd --permanent --zone=internal --add-source=10.0.0.0/24      # a network into a zonefirewall-cmd --permanent --zone=public --change-interface=eth0         # an interface into a zonefirewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="10.0.0.0/24" service name="ssh" accept'