ethtool是设置网卡属性、IP/TCP相关协议属性的基本工具，功能还是很强大的。ubuntu的版本里没有默认集成，使用apt-get install 安装之。。。。
使用概要：
ethtool ethx //查询ethx网口基本设置，其中 x 是对应网卡的编号，如eth0、eth1等等
ethtool –h //显示ethtool的命令帮助(help)
ethtool –i ethX //查询ethX网口的相关信息
ethtool –d ethX //查询ethX网口注册性信息
ethtool –r ethX //重置ethX网口到自适应模式
ethtool –S ethX //查询ethX网口收发包统计
ethtool –s ethX [speed 10|100|1000] [duplex half|full] [autoneg on|off] //设置网口速率10/100/1000M、设置网口半/全双工、设置网口是否自协商
ethtool -k //查看protocol offload的属性
ethtool -K|--offload DEVNAME Set protocol offload // 设置protocol offload的属性，这个命令很强大，待会再讲
[ rx on|off ]
[ tx on|off ]
[ sg on|off ]
[ tso on|off ]
[ ufo on|off ]
[ gso on|off ]
[ gro on|off ]
[ lro on|off ]
[ rxvlan on|off ]
[ txvlan on|off ]
[ ntuple on|off ]
[ rxhash on|off ]
使用举例：
1）[root@linux /]# ethtool eth1
Settings for eth1:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: umbg
Wake-on: d
Link detected: yes
2）[root@linux /]# ethtool -i eth1
driver: e1000
version: 5.0.43-k1
firmware-version: N/A
bus-info: 06:08.1
3）[root@linux /]# ethtool -S eth1
NIC statistics:
rx_packets: 58068300
tx_packets: 87124083
rx_bytes: 1589713008
tx_bytes: 2165825901
rx_errors: 0
tx_errors: 0
rx_dropped: 0
tx_dropped: 0
multicast: 0
collisions: 0
rx_length_errors: 0
rx_over_errors: 0
rx_crc_errors: 0
rx_frame_errors: 0
rx_fifo_errors: 0
rx_missed_errors: 0
tx_aborted_errors: 0
tx_carrier_errors: 0
tx_fifo_errors: 0
tx_heartbeat_errors: 0
tx_window_errors: 0
4） 把网卡eth0 速度改为10Mb/s，采用半双工；
[root@cuc03 beinan]# ethtool -s eth1 speed 10 duplex half
[root@cuc03 beinan]# ethtool eth1
Settings for eth1:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: No
Speed: 10Mb/s 注：速度 10M/s
Duplex: Half 注：半双工
Port: MII
PHYAD: 32
Transceiver: internal
Auto-negotiation: off
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000007 (7)
Link detected: no 注：eth1没有激活；
5）把网卡eth0 速度改为100Mb/s，采用全双工；
[root@cuc03 beinan]# ethtool -s eth1 speed 100 duplex full
[root@cuc03 beinan]# ethtool eth1
Settings for eth1:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: No
Speed: 100Mb/s 注：速度 100M/s
Duplex: Full 注：全双工
Port: MII
PHYAD: 32
Transceiver: internal
Auto-negotiation: off
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000007 (7)
Link detected: no 注：eth1网卡没有激活；
6） 最后关于这个ethtool -k eth0 就特别说明一下，这个是显示网卡的一些特别的协议开关
root@node4:/home/fbw# ethtool -k eth0
Offload parameters for eth0:
rx-checksumming: on
tx-checksumming: off
scatter-gather: off
tcp-segmentation-offload: off
udp-fragmentation-offload: off
generic-segmentation-offload: off
generic-receive-offload: on
large-receive-offload: off
rx-vlan-offload: on
tx-vlan-offload: on
ntuple-filters: off
receive-hashing: on
特别注意，加红的那个参数，之前看到别人遇到这个问题，在部署OpenStack的计算节点的时候，如何将computer部署在台式机上，ssh连接虚拟机就特别卡，连接超时将近1多钟，但是如果将其部署在刀片上就没有任何问题。于是，后面将问题定位到台式机的BCM的网卡上，发现只要敲一下 ethtool -K eth0 tx off ，即只要关掉包发送校检和，就可以正常ssh连接。