如何察看Linux下网络连接速度，以及是否连接网线

首先要确认是否安装了ethtool工具。
[root@eden /]# rpm -q ethtool
ethtool-6-2.20090115git.fc10.x86_64
        安装好后，可以是用ethtool来查看本地连接是否连接了，并查看连接的速度
[root@eden /]# ethtool eth0
Settings for eth0:
    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: Yes
    Speed: 10Mb/s                
    Duplex: Half
    Port: MII
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: pumbg
    Wake-on: g
    Current message level: 0x00000033 (51)
    Link detected: no                   －－－》本地连接没有连接上

转：

Ethtool是用于查询及设置网卡参数的命令。
概要：
ethtool ethX      //查询ethX网口基本设置
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]\         //设置网口速率10/100/1000M
[duplex half|full]\           //设置网口半/全双工
[autoneg on|off]\            //设置网口是否自协商
[port tp|aui|bnc|mii]\         //设置网口类型
[phyad N]\                
[xcvr internal|exteral]\
[wol p|u|m|b|a|g|s|d...]\
[sopass xx:yy:zz:aa:bb:cc]\
[msglvl N]

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）[root@linux /]# ethtool -s eth1 autoneg off speed 100 duplex full

相关：

1）[root@linux /]# which ethtool

    /sbin/ethtool

2）[root@linux /]# rpm -qf /sbin/ethtool

   ethtool-1.6-5

3）怎样使ethtool设置永久保存在网络设备中？

   解决方法一:

    ethtool设置可通过/etc/sysconfig/network-scripts/ifcfg-ethX文件保存,从而在设备下次启动时激活选项。

例如：ethtool -s eth0 speed 100 duplex full autoneg off

此指令将eth0设备设置为全双工自适应，速度为100Mbs。若要eth0启动时设置这些参数, 修改文件/etc/sysconfig/network-scripts/ifcfg-eth0 ，添加如下一行:

ETHTOOL_OPTS="speed 100 duplex full autoneg off"

解决方法二:

将ethtool设置写入/etc/rc.d/rc.local之中。