Network

Check network interface link speed

ip utility

ip -a | grep -i qlen

kernel

cat /sys/classes/net/<interface_name>/speed

ethtool utility

ethtool <interface_name> | grep -i speed

Find duplicate IPs in network

arp <ip_address>

Ping

ping _gateway # default gateway

Print all IPs and interfaces in colorize and tabular format

ip -br -c addr show
ip -br -c link show