Linux基础知识:网络属性配置-演道网

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当我们拥有一个崭新的计算机的时候,第一步恐怕都是迫不及待的下载各种软件,看视频,听音乐等,这里的关键的一点是要有网络。现在的个人计算机大部分都是Windows操作系统的,接入网络网络很简单,插上网线也许就能上网了,最麻烦不过找到网络和共享中心手动配置一个ip地址、网关地址和dns服务器就能上网了,当然这都是得益于图形化界面。但是现在很多的服务器都是Linux操作系统且没有图形化的界面,这时候我们就需要了解怎样正确的给Linux主机配置网络属性了,本次博客就来说说以正确的方式打开Linux操作系统的网络属性配置(本次博客基于的发行版和版本:CentOS7、CentOS6.5)。

接入网络的两种方式

一、手动的指定

1.使用命令

一般是临时的修改,重启后失效,如:ifconfig、route、ip addr等。

2.修改配置文件

修改文件配置,永久有效,但是可能不能立即生效,需要重启服务。

二、动态获取

如果本地网路中存在DHCP服务,可以动态的获取到ip地址、网关地址、DNS服务器地址等。

常用的管理和配置命令

一、ifconfig

1.不加任何选项,查看处于活动状态下的接口,-a选项显示所有接口,包括inactive状态的接口:

[root@localhost ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:AD  
          inet addr:192.168.172.136  Bcast:192.168.172.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aaad/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2168 errors:0 dropped:0 overruns:0 frame:0
          TX packets:404 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:149715 (146.2 KiB)  TX bytes:29251 (28.5 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
[root@localhost ~]# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:AD  
          inet addr:192.168.172.136  Bcast:192.168.172.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aaad/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2223 errors:0 dropped:0 overruns:0 frame:0
          TX packets:425 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:153927 (150.3 KiB)  TX bytes:32473 (31.7 KiB)

eth1      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:B7  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

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接口的命名方式:

1.传统的命令方式:
  以太网:eth1,eth2...ethn  #centos6较常见的命名方式
  PPP网络:ppp1,ppp2...pppn
2.可预测的命令方案
如果固件或者BIOS为主板上集成的设备提供的索引信息可以用,根据此索引进行命令,例如:eno1,eno2....enon;
如果固件或者BIOS为PCI-E扩展槽上所提供的索引信息可以用,根据此索引进行命令,例如:ens1,ens2...ensn;
如果硬件接口的物理位置信息可用,则根据此信息命令,如enp2s0
如果用户显示定义,也可以根据MAC地址命令,例如enx1232131231
3.命名格式的组成
en:以太网
wl:无线网
ww:广域网
4.名称类型
o:集成设备的设备索引号
s:扩展槽的索引号
x:基于MAC地址的命名
ps:基于总线槽的拓扑结构进行命名

接口命名方式

2. 配置接口ip地址掩码的两种方式:

ifconfig INTERFACE IP/MASK [up|down]      #up和down为可选项
ifconfig INTERFACE IP netmask NETMASK [up|down]

举例:

[root@localhost ~]# ifconfig eth1 192.168.1.1/24 up
[root@localhost ~]# 
[root@localhost ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:AD  
          inet addr:192.168.172.136  Bcast:192.168.172.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aaad/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2392 errors:0 dropped:0 overruns:0 frame:0
          TX packets:510 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:168403 (164.4 KiB)  TX bytes:43303 (42.2 KiB)

eth1      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:B7  
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aab7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:398 (398.0 b)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

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3.开启接口的杂合模式,这里就不先做太多的说明,后面博客中会说明:

[root@localhost ~]# ifconfig eth1 promisc
[root@localhost ~]# 
[root@localhost ~]# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:B7  
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aab7/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1    #这里多了一个PROMISC
          RX packets:29 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2985 (2.9 KiB)  TX bytes:468 (468.0 b)

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4.新增和删除IPv6地址

ifconfig INTERFACE add addr/prefixlen
ifconfig INTERFACE del addr/prefixlen

举例:

[root@localhost ~]# ifconfig eth1 add 2001:0:0:12::1/64  #新增一个IPV6地址
[root@localhost ~]# 
[root@localhost ~]# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:B7  
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: 2001:0:0:12::1/64 Scope:Global
          inet6 addr: fe80::20c:29ff:fe9f:aab7/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:57 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:6604 (6.4 KiB)  TX bytes:836 (836.0 b)
[root@localhost ~]# ifconfig eth1 del 2001:0:0:12::1/64  #删除ipv6地址
[root@localhost ~]# 
[root@localhost ~]# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:0C:29:9F:AA:B7  
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe9f:aab7/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:62 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:7468 (7.2 KiB)  TX bytes:1016 (1016.0 b)

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如果在没有配置ipv6地址的情况下,我们会发现每个接口都有一个开头为fe80的ipv6地址,这个地址被称为链路本地的地址,其前64为都是固定的格式,后64是位是基于EUI-64生成的,通俗的来说就是基于MAC地址生成的,链路本地地址只能用户本地的通信,如果想要实现上网的功能,就必须要给接口配置一个全局的地址,也就是全球可聚合单播地址,配置的方式就如上,显示为Global。

可以给接口起别名配置多个IP地址:

[root@localhost ~]# ifconfig ens34:1 192.168.179.130 netmask 255.255.255.0
[root@localhost ~]# 
[root@localhost ~]# ifconfig
ens32: flags=4163  mtu 1500
        inet 192.168.172.134  netmask 255.255.255.0  broadcast 192.168.172.255
        inet6 fe80::4:ed31:efad:25d0  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:47  txqueuelen 1000  (Ethernet)
        RX packets 25157  bytes 12826364 (12.2 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 11651  bytes 2175604 (2.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens34: flags=4163  mtu 1500
        inet 192.168.179.128  netmask 255.255.255.0  broadcast 192.168.179.255
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 666  bytes 91944 (89.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 220  bytes 29356 (28.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens34:1: flags=4163  mtu 1500
        inet 192.168.179.130  netmask 255.255.255.0  broadcast 192.168.179.255
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)

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然后为别名添加配置文件即可,记得DEVICE为别名名称且BOOTPROTO:不支持动态获取地址。

注意:执行ifconfig的时候,命令执行后立即生效的,但是重启后失效!

 

二、route

1.查看路由条目

route -n #用数字表示,不加-n选项,可能会以主机名和其他的符号来显示地址

举例:

[root@localhost ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.172.0   *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     1002   0        0 eth0
default         192.168.172.2   0.0.0.0         UG    0      0        0 eth0
[root@localhost ~]# 
[root@localhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 eth0

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2.添加路由条目

route add [-net|-host]  target [netmask Nm]  [gw GW] [[dev] If]

举例:

[root@localhost ~]# route add -net 100.100.100.0/24  gw 192.168.1.1  #接口可省略
[root@localhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
100.100.100.0   192.168.1.1     255.255.255.0   UG    0      0        0 eth1
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 eth0
[root@localhost ~]# route add default gw 192.168.1.1 dev eth1  #使用default参数创建默认路由
[root@localhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
100.100.100.0   192.168.1.1     255.255.255.0   UG    0      0        0 eth1
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth1
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 eth0

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3.删除路由

route del [-net|-host] target [gw GW] [netmask Nm] [[dev] If]

举例:

[root@localhost ~]# route del -net 100.100.100.0/24 
[root@localhost ~]# route del -net 0.0.0.0/0 gw 192.168.1.1  #如果目的IP地址存在多个,可以指定网关地址,避免误删
[root@localhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 eth0

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三、netstat命令

专门用来显示命令

1.显示路由表

netstat -rn
-r:显示内核路由表
-n:数字格式

举例:

[root@localhost ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
192.168.172.0   0.0.0.0         255.255.255.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG        0 0          0 eth0

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2.显示网络连接

netstat  [--tcp|-t]  [--udp|-u]  [--udplite|-U]  [--sctp|-S]  [--raw|-w]  [--listening|-l]  [--all|-a]  [--numeric|-n]   [--extend|-e[--extend|-e]]  [--program|-p]
-t:TCP的相关连接
-u:UDP相关连接
-w:raw socket相关连接
-l:处于监听状态的连接
-a:所有状态
-n:以数字格式显示ip和端口
-e:扩展格式
-p:显示相关进程及PID

常用组合:
-tan -uan -tnl -unl -tunlp

举例:

[root@localhost ~]# netstat -tan
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State      
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      
tcp        0     64 192.168.172.136:22          192.168.172.1:60645         ESTABLISHED 
tcp        0      0 :::22                       :::*                        LISTEN      
tcp        0      0 ::1:25                      :::*                        LISTEN      
[root@localhost ~]# netstat -uan
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State      
udp        0      0 0.0.0.0:68                  0.0.0.0:*                               
[root@localhost ~]# netstat -tnl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State      
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      
tcp        0      0 :::22                       :::*                        LISTEN      
tcp        0      0 ::1:25                      :::*                        LISTEN      
[root@localhost ~]# netstat -unl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State      
udp        0      0 0.0.0.0:68                  0.0.0.0:*                               
[root@localhost ~]# netstat -tunlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      1008/sshd           
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      1084/master         
tcp        0      0 :::22                       :::*                        LISTEN      1008/sshd           
tcp        0      0 ::1:25                      :::*                        LISTEN      1084/master         
udp        0      0 0.0.0.0:68                  0.0.0.0:*                               904/dhclient   

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3.显示接口的统计数据

netstat    {--interfaces|-I|-i}    [iface]   [--all|-a]   [--extend|-e]   [--verbose|-v]   [--program|-p]  [--numeric|-n]
所有接口的信息:netstat -i
指定的接口:netstat -I

举例:

[root@localhost ~]# netstat -i
Kernel Interface table
Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0       1500   0     2288      0      0      0     1099      0      0      0 BMRU
eth1       1500   0        8      0      0      0        6      0      0      0 BMRU
lo        16436   0        0      0      0      0        0      0      0      0 LRU
[root@localhost ~]# netstat -Ieth1
Kernel Interface table
Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth1       1500   0        8      0      0      0        6      0      0      0 BMRU

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四、ifup和ifdown

开启或者关闭接口,通过配置文件来识别接口并完成配置,如果接口没有配置文件,则不能生效。

ifup INTERFACE
ifdown  INTERFACE

 

五、ip

ip的功能很强大,这里只做一些常用的用法的介绍,具体可以见man手册。

NAME:show / manipulate routing, devices, policy routing and tunnels
ip [ OPTIONS ] OBJECT { COMMAND | help }
    OBJECT := { link | addr | route | netns  } #注意,在写命令的时候,OBJECT可以简写,各个OBJECT的子命令也可以简写

1. ip link:网络设备管理

ip link set:修改设备的属性
dev NAME:默认参数,指明要管理的设备,关键字dev可以省略;
         {up|down}:开启或关闭设备
         {multicast on|multicast off}:开启或关闭多播功能
         {name NAME}:重命名接口,必须先将设备关闭
         netns PID|netnsname:netns为名称空间,将接口移动到指定的网络名称空间
ip link show:查看设备的状态
ip link help:显示帮助信息

举例:

[root@localhost ~]# ip link set ens34 down  #关闭ens34
[root@localhost ~]# ip link set ens34 name eth34  #重命名
[root@localhost ~]# 
[root@localhost ~]# ifconfig -a
ens32: flags=4163  mtu 1500
        inet 192.168.172.134  netmask 255.255.255.0  broadcast 192.168.172.255
        inet6 fe80::4:ed31:efad:25d0  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:47  txqueuelen 1000  (Ethernet)
        RX packets 14177  bytes 10140644 (9.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5848  bytes 1208376 (1.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth34: flags=4098  mtu 1500
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 399  bytes 55093 (53.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 102  bytes 15624 (15.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@localhost ~]# ip link set eth34 name ens34
[root@localhost ~]# ip link set ens34 up
[root@localhost ~]# ifconfig
ens32: flags=4163  mtu 1500
        inet 192.168.172.134  netmask 255.255.255.0  broadcast 192.168.172.255
        inet6 fe80::4:ed31:efad:25d0  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:47  txqueuelen 1000  (Ethernet)
        RX packets 14382  bytes 10157346 (9.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5954  bytes 1220936 (1.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens34: flags=4163  mtu 1500
        inet 192.168.179.128  netmask 255.255.255.0  broadcast 192.168.179.255
        inet6 fe80::3062:d2dc:471:6045  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 403  bytes 55727 (54.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 112  bytes 16702 (16.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

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2.ip netns:管理网络名称空间(manage network namespaces)

ip netns list:列出所有的网络名称空间
ip netns add NAME:创建指定的网络名称空间
ip netns del NAME:删除指定的网络名称空间
ip netns exec NAME COMMAND:在指定的netns中运行命令

举例:

[root@localhost ~]# ip netns add mynetns  #创建了一个名称空间
[root@localhost ~]# 
[root@localhost ~]# ip netns list  #查看名称空间
mynetns
[root@localhost ~]# ip link set ens34 netns mynetns  #将ens34绑定到名称空间mynetns
[root@localhost ~]# ifconfig -a    #这时候我们会发现设备没有了
ens32: flags=4163  mtu 1500
        inet 192.168.172.134  netmask 255.255.255.0  broadcast 192.168.172.255
        inet6 fe80::4:ed31:efad:25d0  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:47  txqueuelen 1000  (Ethernet)
        RX packets 14892  bytes 10199499 (9.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6234  bytes 1258060 (1.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1  (Local Loopback)
        RX packets 72  bytes 6260 (6.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 72  bytes 6260 (6.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@localhost ~]# ip link show   
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens32:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:0c:29:db:7f:47 brd ff:ff:ff:ff:ff:ff
[root@localhost ~]# ip netns exec mynetns ip link show  #只有在名称空间内执行命令才能看到,使用ifconfig无效
1: lo:  mtu 65536 qdisc noop state DOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: ens34:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether 00:0c:29:db:7f:51 brd ff:ff:ff:ff:ff:ff
[root@localhost ~]# ip netns exec mynetns ip link set ens34 up  #启用接口
[root@localhost ~]# ip netns exec mynetns ip link show
1: lo:  mtu 65536 qdisc noop state DOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: ens34:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:0c:29:db:7f:51 brd ff:ff:ff:ff:ff:ff

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3.ip address:协议地址管理(protocol address management)

ip address IFADDR dev INTERFACE:新增地址,一个接口可以有多个地址
ip address delete IFADDR dev INTERFACE:删除接口的地址
ip address show [INTERFACE]:显示接口地址
ip address flush dev INTERFACE:删除接口地址

举例:

[root@localhost ~]# ip address flush ens34
[root@localhost ~]# ifconfig
ens32: flags=4163  mtu 1500
        inet 192.168.172.134  netmask 255.255.255.0  broadcast 192.168.172.255
        inet6 fe80::4:ed31:efad:25d0  prefixlen 64  scopeid 0x20
        ether 00:0c:29:db:7f:47  txqueuelen 1000  (Ethernet)
        RX packets 15955  bytes 10285157 (9.8 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6762  bytes 1356066 (1.2 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens34: flags=4163  mtu 1500
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 413  bytes 57483 (56.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 138  bytes 18976 (18.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@localhost ~]# ip address add 192.168.179.22/24 dev ens34
[root@localhost ~]# 
[root@localhost ~]# ifconfig ens34
ens34: flags=4163  mtu 1500
        inet 192.168.179.22  netmask 255.255.255.0  broadcast 0.0.0.0
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 416  bytes 57775 (56.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 141  bytes 19212 (18.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@localhost ~]# ip address  delete 192.168.179.22/24 dev ens34
[root@localhost ~]# ifconfig ens34
ens34: flags=4163  mtu 1500
        ether 00:0c:29:db:7f:51  txqueuelen 1000  (Ethernet)
        RX packets 424  bytes 58479 (57.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 149  bytes 19804 (19.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@localhost ~]# ip address show
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens32:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:db:7f:47 brd ff:ff:ff:ff:ff:ff
    inet 192.168.172.134/24 brd 192.168.172.255 scope global dynamic ens32
       valid_lft 1180sec preferred_lft 1180sec
    inet6 fe80::4:ed31:efad:25d0/64 scope link 
       valid_lft forever preferred_lft forever
3: ens34:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:db:7f:51 brd ff:ff:ff:ff:ff:ff

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4.ip route:路由表管理(routing table management)

ip route add  TYPE PREFIX  via GW  [dev  IFACE]  [src SOURCE_IP]:新增一条路由
ip route delete TYPE PREFIX:删除路由
ip route show [TYPE PRIFIX]:查看路由
ip route flush:清空路由
ip route get TYPE PREFIX:获得一个单独的路由信息
详见帮助信息:man  ip route

举例:

[root@localhost ~]# ip route show
default via 192.168.172.2 dev ens32  proto static  metric 100 
192.168.172.0/24 dev ens32  proto kernel  scope link  src 192.168.172.134  metric 100 
192.168.179.0/24 dev ens34  proto kernel  scope link  src 192.168.179.128 
192.168.179.0/24 dev ens34  proto kernel  scope link  src 192.168.179.128  metric 100 
[root@localhost ~]# 
[root@localhost ~]# ip route add 100.100.100.0/24 via 192.168.179.128 dev ens34
[root@localhost ~]# 
[root@localhost ~]# ip route show
default via 192.168.172.2 dev ens32  proto static  metric 100 
100.100.100.0/24 via 192.168.179.128 dev ens34 
192.168.172.0/24 dev ens32  proto kernel  scope link  src 192.168.172.134  metric 100 
192.168.179.0/24 dev ens34  proto kernel  scope link  src 192.168.179.128 
192.168.179.0/24 dev ens34  proto kernel  scope link  src 192.168.179.128  metric 100 
[root@localhost ~]# ip route show 100.100.100.0/24
100.100.100.0/24 via 192.168.179.128 dev ens34 
[root@localhost ~]# ip route get 100.100.100.0/24
100.100.100.0 dev ens34  src 192.168.179.128 
    cache 

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六、ss命令

ss和netstat的功能类似,但是比netstat的功能强大。

net [options] [FILTER]
options:
-t:TCP的相关连接
-u:UDP的相关连接
-w:raw socket的相关连接
-l:监听状态的连接
-a:所有状态的连接
-n:数字格式显示
-p:相关的程序及其PID
-e:扩展格式信息
-m:内存用量
-o:计时器信息
FILTER:
[ state TCP-STATE ]  [ EXPRESSION ]
TCP-STATE:
LISTEN:监听
ESTABLISEHD:已经建立连接
FIN_WAIT_1:
FIN_WAIT_2:
SYN_SENT:
SYN_RECV:
CLOSED:
EXPRESSION:
dport:目的端口
sport:源端口
...

举例:

[root@localhost ~]# ss -tan
State      Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
LISTEN     0      128                                   *:22                                                *:*                  
LISTEN     0      100                           127.0.0.1:25                                                *:*                  
ESTAB      0      0                       192.168.172.134:22                                    192.168.172.1:57461              
LISTEN     0      128                                  :::22                                               :::*                  
LISTEN     0      100                                 ::1:25                                               :::*                  
[root@localhost ~]# ss -tanp
State      Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
LISTEN     0      128                                   *:22                                                *:*                   users:(("sshd",pid=943,fd=3))
LISTEN     0      100                           127.0.0.1:25                                                *:*                   users:(("master",pid=1038,fd=13))
ESTAB      0      180                     192.168.172.134:22                                    192.168.172.1:57461               users:(("sshd",pid=1074,fd=3))
LISTEN     0      128                                  :::22                                               :::*                   users:(("sshd",pid=943,fd=4))
LISTEN     0      100                                 ::1:25                                               :::*                   users:(("master",pid=1038,fd=14))
[root@localhost ~]# ss -uan
State      Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
ESTAB      0      0                       192.168.172.134:60204                                61.216.153.106:123                
UNCONN     0      0                             127.0.0.1:323                                               *:*                  
UNCONN     0      0                                     *:1524                                              *:*                  
UNCONN     0      0                                     *:68                                                *:*                  
UNCONN     0      0                                     *:68                                                *:*                  
UNCONN     0      0                                     *:30403                                             *:*                  
UNCONN     0      0                                    :::27349                                            :::*                  
UNCONN     0      0                                   ::1:323                                              :::*                  
UNCONN     0      0                                    :::5011                                             :::*  
[root@localhost ~]# ss -tan '( dport = :22 or sport = :22  )'
State      Recv-Q Send-Q                    Local Address:Port                                   Peer Address:Port              
LISTEN     0      128                                   *:22                                                *:*                  
ESTAB      0      52                      192.168.172.134:22                                    192.168.172.1:57461              
LISTEN     0      128                                  :::22                                               :::*            
[root@localhost ~]# 
[root@localhost ~]# ss -tan state ESTABLISHED
Recv-Q Send-Q                         Local Address:Port                                        Peer Address:Port              
0      52                           192.168.172.134:22                                         192.168.172.1:57461 

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七、配置主机名

hostname

hostname:查看主机名
hostname HOSTNAME:修改主机名,重启后无效

在centos7中:

hostnamectl status:显示当前主机名等信息
hostnamectl  set-hostname HOSTNAME:设置主机名,永久有效

 

网络属性配置文件

一、主机名的配置文件

/etc/sysconfig/network (在centos7有这个文件,但是为空,因为在centos7中新增了hostnamectl  set-hostname,可以设置永久有效的主机名了):

centos6:
[root@localhost ~]# vim /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=localhost.localdomain

注意:修改配置文件不会立即生效,但是以后会一直有效。

 

二、DNS的配置文件

/etc/hosts:负责ip地址与域名快速解析的文件,hosts文件包含了IP地址和主机名之间的映射,在域名解析的过程中,会先查看hosts文件中是否有域名和ip地址之间的映射关系,如果没有则向DNS服务器发起域名解析的请求:

[root@frankhost ~]# vim /etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

/etc/resolv.conf:配置的是DNS服务器的地址,当主机要访问某个域名的时候,就会向resolv.conf的中的DNS服务器发起解析的请求:

[root@localhost ~]# vim /etc/resolv.conf 

# Generated by NetworkManager
search localdomain
nameserver 192.168.172.2
nameserver 192.168.179.1

 

三、接口和路由的配置文件

/etc/sysconfig/network-scripts/ifcfg-IFACE:通过大量的参数来定义接口的属性,可以通过vim等文本编辑器直接修改:

[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens32 

TYPE=Ethernet    #接口类型
BOOTPROTO=dhcp   #激活此接口使用什么协议来配置接口的属性,有dhcp、bootp、static、none等
DEFROUTE=yes     #是否以此接口创建默认路由
PEERDNS=yes      #如果BOOTPROTO的值为DHCP,是否允许dhcp server分配的dns服务器指向覆盖本地手动指定的DNS服务器指向
PEERROUTES=yes   
IPV4_FAILURE_FATAL=no
IPV6INIT=yes    #是否初始化IPV6
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens32   #此配置文件对于的设备名称
UUID=a3471195-913d-4e38-b521-47ffa1859ffe  #此设备的唯一标识
DEVICE=ens32  #此设备文件对于的设备名称
ONBOOT=yes

除了以上的一些参数之外还有其他一些比较重要的参数:

DNS1:DNS指向,最多可以有三个
DOMAIN:DNS搜索域
IPADDR:ip地址
NETMASK:子网掩码;在centos7中支持使用PREFIX以长度方式指明子网掩码
GATEWAY:默认网关
USERCTL:是否允许普通用户控制
HWADDR:设备的MAC地址
NM_CONTROLLED:是否使用NetworkManager服务来控制接口

 

/etc/sysconfig/network-scripts/route-IFACE:针对每个接口都有其对应的路由配置文件,有两种配置方式,但是不可以混用:
(1)每行配置一条路由:

target/prefix via GW

(2)每三行配置一条路由:

ADDRESS#=target
NETWORK#=mask
GATEWAY#=NEXTHOP
#为数字0.1.2.3....

举例:

[root@frankhost ~]# vim /etc/sysconfig/network-scripts/route-eth0

100.100.100.0/24 via 192.168.172.136
[root@frankhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
100.100.100.0   192.168.172.136 255.255.255.0   UG    0      0        0 eth0
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 


[root@frankhost ~]# vim /etc/sysconfig/network-scripts/route-eth0

ADDRESS0=192.168.1.0
NETMASK0=255.255.255.0
GATEWAY0=192.168.172.136
[root@frankhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     192.168.172.136 255.255.255.0   UG    0      0        0 eth0
192.168.172.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
0.0.0.0         192.168.172.2   0.0.0.0         UG    0      0        0 eth0      

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图像化的方式配置网络属性

在centos6中:

执行system-config-network或者setup命令:

安装:yum -y install system-config-network-tui

安装:yum -y install setuptool

setup界面:

在centos7中:
执行nmtui命令

 

该怎么用就不多说了,毕竟是傻瓜式的配置,永久有效。

在centos7中有一个很强大也很复杂的网络配置管理命令:nmcli,这里暂时就不做介绍了,以后有机会单独写一篇博客,nmcli参考链接:http://www.linuxidc.com/Linux/2015-09/123179.htm,或者请看man手册。

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