root@xubuntu:~# dmesg | grep Duplex
[   54.142430] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
[ 1468.605163] e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
root@xubuntu:~# 
root@xubuntu:~# 
root@xubuntu:~# ethtool eth0
Settings for eth0:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Supported pause frame use: No
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
	Speed: 100Mb/s
	Duplex: Full
	Port: Twisted Pair
	PHYAD: 2
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: off (auto)
	Supports Wake-on: pumbg
	Wake-on: g
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes