每天一个Linux命令（46）ifconfig命令

在windows系统中，ipconfig命令行工具被用来获取网络接口配置信息并对此进行修改。Linux系统拥有一个类似的工具，也就是ifconfig(interfaces config)。

    (1)用法:

    用法:  ifconfig [网络设备] [参数]

    (2)功能:

    功能:  ifconfig命令用来查看和配置网络设备，当网络环境发生改变时可通过此命令对网络进行相应的配置。

注意:  用ifconfig命令配置的网卡信息，在网卡重启后机器重启后，配置就不存在。要想将上述的配置信息永远的存在电脑里，那就要修改网卡的配置文件了。

    (3)选项参数:

1)  up 　　　　     　　启动指定网络设备/网卡。

2)  down 　　      　　 关闭指定网络设备/网卡。该参数可以有效地阻止通过指定接口的IP信息流，如果想永久地关闭一个接口，我们还需要从核心路由表中将该接口的路由信息全部删除。

3) -a　　　　　　 　　 无论是否激活，显示所有配置的网络接口。

4) add 　　　　  　　 给指定网卡配置IPv6地址

　　5) del　　　　　　　　  删除指定网卡的IPv6地址

6) arp|-arp　　　 　　  打开或关闭支持ARP协议

7) mtu<字节数>  　　  设置网卡的最大传输单元

8) netmask<子网掩码> 设置网卡的子网掩码

    (4)实例:

1)[sunjimeng@localhost ~]$ ifconfig　　　　　　　　

[sunjimeng@localhost ~]$ ifconfig 　　　　　　　　//未联网时的参数
eno16777736: flags=<UP,BROADCAST,RUNNING,MULTICAST>  mtu
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (170.8 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (0.0 B)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (274.8 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (274.8 KiB)
        TX errors   dropped  overruns   carrier   collisions 

[sunjimeng@localhost ~]$ ifconfig                   //连接到有线网时的参数
eno16777736: flags=<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500                //mtu表示最大传输单元
        inet 192.168.117.128  netmask 255.255.255.0  broadcast 192.168.117.255
        inet6 fe80::20c:29ff:fe4d:a3cc  prefixlen 64  scopeid 0x20<link>
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (177.7 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (6.1 KiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (303.1 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (303.1 KiB)
        TX errors   dropped  overruns   carrier   collisions 

    说明:

　　1）etn(Number)指的是网卡，可以看到目前这个网卡的物理地址(MAC地址）是 00:0c:29:4d:a3:cc。

2）inet后表示ip地址，此网卡的ip地址是192.168.117.128，广播地址是192.168.117.255，掩码地址为255.255.255.0。

3）lo是表示主机的回坏地址，这个一般是用来测试一个网络程序，但又不想让局域网或外网的用户能够查看，只能在此台主机上运行和查看所用的网络接口。

　　比如把 http服务器指定到回环地址，在浏览器输入127.0.0.1就能看到你所架WEB网站了。但只是您能看得到，局域网的其它主机或用户无从知道。

2)[root@localhost sunjimeng]# ifconfig eno16777736 down　　　　打开和关闭指定网卡

[sunjimeng@localhost ~]$ ifconfig eno16777736 down　　　　　　//必须是root权限才可以
SIOCSIFFLAGS: 不允许的操作
[sunjimeng@localhost ~]$ su root
密码：
[root@localhost sunjimeng]# ifconfig eno16777736 down
[root@localhost sunjimeng]# ifconfig
lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (303.9 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (303.9 KiB)
        TX errors   dropped  overruns   carrier   collisions
[root@localhost sunjimeng]# ifconfig eno16777736 up
[root@localhost sunjimeng]# ifconfig
eno16777736: flags=<UP,BROADCAST,RUNNING,MULTICAST>  mtu
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (181.3 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (9.4 KiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (304.2 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (304.2 KiB)
        TX errors   dropped  overruns   carrier   collisions 

注意：ssh登陆linux服务器，关闭了网卡就不能开启了，除非你有多网卡。

3)[root@localhost sunjimeng]# ifconfig -a　　　　　　无论是否激活，显示所有配置的网络接口，不带参数的只显示已激活的网络接口

[root@localhost sunjimeng]# ifconfig -a
eno16777736: flags=<UP,BROADCAST,RUNNING,MULTICAST>  mtu
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (181.6 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (9.4 KiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (304.2 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (304.2 KiB)
        TX errors   dropped  overruns   carrier   collisions 

4)启用或关闭支持ARP协议

[root@localhost sunjimeng]# ifconfig eno16777736 arp
[root@localhost sunjimeng]# ifconfig eno16777736 -arp

5)[root@localhost sunjimeng]# ifconfig eno16777736 mtu 2000　　　　设置网络设备传输的最大单元

[root@localhost sunjimeng]# ifconfig
eno16777736: flags=<UP,BROADCAST,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 192.168.117.128  netmask 255.255.255.0  broadcast 192.168.117.255
        inet6 fe80::20c:29ff:fe4d:a3cc  prefixlen   scopeid 0x20<link>
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (103.3 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (1.2 MiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (356.3 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (356.3 KiB)
        TX errors   dropped  overruns   carrier   collisions 

[root@localhost sunjimeng]# ifconfig eno16777736 mtu
[root@localhost sunjimeng]# ifconfig
eno16777736: flags=<UP,BROADCAST,RUNNING,NOARP,MULTICAST>  mtu
        ether :0c::4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (138.3 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (1.2 MiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (414.3 KiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (414.3 KiB)
        TX errors   dropped  overruns   carrier   collisions 

6)[root@localhost sunjimeng]# ifconfig eno16777736 hw ether 00:0c:29:4d:a3:dd　　　　设置网卡的mac地址

[root@localhost sunjimeng]# ifconfig
eno16777736: flags=<UP,BROADCAST,RUNNING,NOARP,MULTICAST>  mtu
        inet 0.0.0.64  netmask 0.0.0.0  broadcast 255.255.255.255
        ether 00:0c:29:4d:a3:cc  txqueuelen   (Ethernet)
        RX packets   bytes  (151.8 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (1.2 MiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (2.6 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (2.6 MiB)
        TX errors   dropped  overruns   carrier   collisions 

[root@localhost sunjimeng]# ifconfig eno16777736 hw ether :0c::4d:a3:dd
[root@localhost sunjimeng]# ifconfig
eno16777736: flags=<UP,BROADCAST,RUNNING,NOARP,MULTICAST>  mtu
        inet 0.0.0.64  netmask 0.0.0.0  broadcast 255.255.255.255
        ether 00:0c:29:4d:a3:dd  txqueuelen   (Ethernet)
        RX packets   bytes  (151.8 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (1.2 MiB)
        TX errors   dropped  overruns   carrier   collisions 

lo: flags=<UP,LOOPBACK,RUNNING>  mtu
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::  prefixlen   scopeid 0x10<host>
        loop  txqueuelen   (Local Loopback)
        RX packets   bytes  (2.7 MiB)
        RX errors   dropped   overruns   frame
        TX packets   bytes  (2.7 MiB)
        TX errors   dropped  overruns   carrier   collisions