Ubuntu Linux verify the speed of my NIC (network card)

Fig.01: Ubuntu Linux verify the speed of my NIC (network card)

Fig.01: Ubuntu Linux verify the speed of my NIC (network card)

There is a command that you can use to verify by its output the speed of your NIC is 10 or 100 or 1000 Mbps on Ubuntu Linux. Type the following command:
ethtool eth0
Sample outputs:

Settings for eth0:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supported pause frame use: Symmetric
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: Symmetric
	Advertised auto-negotiation: Yes
	Speed: 1000Mb/s
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: on (auto)
	Supports Wake-on: pumbg
	Wake-on: g
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes

On older version of Ubuntu you can use the following commands too:
mii-tool -v eth0
Sample outputs:

eth0: negotiated, link ok
  product info: vendor 00:55:00, model 59 rev 1
  basic mode:   autonegotiation enabled
  basic status: autonegotiation complete, link ok
  capabilities: 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

Or use the following command:
dmesg | grep eth0 | grep up
Here is another example for bond0 interface:
dmesg | grep bond0 | grep up
Sample outputs:

[   16.269590] bond0: Setting up delay to 0
[   77.406524] bond0: Enslaving eth0 as a backup interface with a down link
[   77.563095] bond0: Enslaving eth2 as a backup interface with a down link
[   81.175492] bond0: link status definitely up for interface eth0, 1000 Mbps full duplex

Examples and usage: Linux - Determine / Find Ethernet Connection Speed