Mii-tool

mii-tool eth0
mii-tool -v eth0

mii-tool eno1
eno1: negotiated 1000baseT-FD flow-control, link ok

mii-tool -v eno1
eno1: negotiated 1000baseT-FD flow-control, link ok
 product info: vendor 00:d8:97, model 34 rev 0
 basic mode:   autonegotiation enabled
 basic status: autonegotiation complete, link ok
 capabilities: 1000baseT-HD 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
 advertising:  1000baseT-HD 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
 link partner: 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD

See also

• ifconfig, ethtool or obsolete mii-tool (mii-tool -v eth0) nmcli device show, eth0, Network manager