linux網絡原理及基本設置

識別網絡設備

  • 開機時Linux讀取/etc/modprobe.conf文件設定、並根據這些設定決定載入哪些網卡的驅動程序模塊
  • 爲了方便系統的管理和維護,網絡設定文件和腳本中都會使用網卡的邏輯名來引用網卡
  • 系統中的第1個網卡的邏輯名是eth0
  • 在/etc/modprobe.conf文件中將這些網卡的邏輯名對應到系統所監測到的特定網卡
  • 好處是可減輕管理員管理和維護系統的工作量

網卡種類與邏輯別名

  • 網卡種類與邏輯別名的對應關係:
    • Ethernet卡:eth爲字首後跟數字編號作邏輯名
    • Token Ring卡:tr爲字首後跟數字編號作邏輯名
    • FDDI卡:fddi爲字首後跟數字編號作邏輯名
    • PPP:ppp爲字首後跟數字編號作邏輯名
  • 每個網卡上都有唯一的編號、該編號由網卡製造商編號和網卡出廠時的序列號兩部分組成的:
    在這裏插入圖片描述

ifconfig或dmesg命令

  • 可使用ifconfig或dmesg命令查看系統上網卡編號
  • ifconfig中if是interface的縮寫、config是configure前6個字母
  • dmesg中d是device第1個字母、mesg是message縮寫
  • 使用ifconfig命令獲取所有正在啓用的網卡信息:
  • 在以上命令顯示結果中HWadd是Hardware Address(硬件地址)的縮寫、緊跟其後的6組由冒號分隔的十六進制數字爲該網卡的硬件地址
[root@dog network-scripts]# vi ficfg-eth0
[root@dog network-scripts]# vi ifcfg-eth0
[root@dog network-scripts]# service network restart
正在關閉接口 eth0: 設備狀態:3 (斷開連接)
                                                           [確定]
關閉環回接口:                                             [確定]
彈出環回接口:                                             [確定]
彈出界面 eth0: 活躍連接狀態:激活中
活躍連接路徑:/org/freedesktop/NetworkManager/ActiveConnection/3
狀態:已激活
連接被激活
                                                           [確定]
[root@dog network-scripts]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:02:55:0F  
          inet addr:192.168.40.132  Bcast:192.168.40.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe02:550f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2669 errors:0 dropped:0 overruns:0 frame:0
          TX packets:128 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:177342 (173.1 KiB)  TX bytes:14196 (13.8 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:65536  Metric:1
          RX packets:16 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1104 (1.0 KiB)  TX bytes:1104 (1.0 KiB)

[root@dog network-scripts]# service network restart
正在關閉接口 eth0: 設備狀態:3 (斷開連接)
                                                           [確定]
關閉環回接口:                                             [確定]
彈出環回接口:                                             [確定]
彈出界面 eth0: 活躍連接狀態:已激活
活躍連接路徑:/org/freedesktop/NetworkManager/ActiveConnection/4
                                                           [確定]
[root@dog network-scripts]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:02:55:0F  
          inet addr:192.168.40.132  Bcast:192.168.40.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe02:550f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2893 errors:0 dropped:0 overruns:0 frame:0
          TX packets:188 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:192377 (187.8 KiB)  TX bytes:19191 (18.7 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:65536  Metric:1
          RX packets:136 errors:0 dropped:0 overruns:0 frame:0
          TX packets:136 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:10512 (10.2 KiB)  TX bytes:10512 (10.2 KiB)


[root@dog network-scripts]# ping www.baidu.com
PING www.a.shifen.com (61.135.169.121) 56(84) bytes of data.
64 bytes from 61.135.169.121: icmp_seq=1 ttl=128 time=99.3 ms
64 bytes from 61.135.169.121: icmp_seq=2 ttl=128 time=88.3 ms
^Z
[7]+  Stopped                 ping www.baidu.com


You have new mail in /var/spool/mail/root
[root@dog network-scripts]# ifdown eth0
設備狀態:3 (斷開連接)
[root@dog network-scripts]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:02:55:0F  
          inet6 addr: fe80::20c:29ff:fe02:550f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11278 errors:0 dropped:0 overruns:0 frame:0
          TX packets:712 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:780819 (762.5 KiB)  TX bytes:70035 (68.3 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:65536  Metric:1
          RX packets:148 errors:0 dropped:0 overruns:0 frame:0
          TX packets:148 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:11446 (11.1 KiB)  TX bytes:11446 (11.1 KiB)


[root@dog network-scripts]# ifup eth0
活躍連接狀態:激活中
活躍連接路徑:/org/freedesktop/NetworkManager/ActiveConnection/15
狀態:已激活
連接被激活
[root@dog network-scripts]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:02:55:0F  
          inet addr:192.168.40.132  Bcast:192.168.40.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe02:550f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11281 errors:0 dropped:0 overruns:0 frame:0
          TX packets:717 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:781297 (762.9 KiB)  TX bytes:70665 (69.0 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:65536  Metric:1
          RX packets:148 errors:0 dropped:0 overruns:0 frame:0
          TX packets:148 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:11446 (11.1 KiB)  TX bytes:11446 (11.1 KiB)


[root@dog network-scripts]# cd /etc/sysconfig/network-scripts
[root@dog network-scripts]# ls
ifcfg-eth0   ifdown-isdn    ifup-aliases  ifup-plusb     init.ipv6-global
ifcfg-lo     ifdown-post    ifup-bnep     ifup-post      net.hotplug
ifdown       ifdown-ppp     ifup-eth      ifup-ppp       network-functions
ifdown-bnep  ifdown-routes  ifup-ippp     ifup-routes    network-functions-ipv6
ifdown-eth   ifdown-sit     ifup-ipv6     ifup-sit
ifdown-ippp  ifdown-tunnel  ifup-isdn     ifup-tunnel
ifdown-ipv6  ifup           ifup-plip     ifup-wireless
[root@dog network-scripts]# ls -l ifcfg*
-rw-r--r--. 1 root root 302 6月   1 22:38 ifcfg-eth0
-rw-r--r--. 1 root root 254 4月  27 2018 ifcfg-lo
[root@dog network-scripts]# cat ifcfg-eth0
DVICE=eth0
TYPE=Ethernet
UUID=8f0e6033-75c6-4efa-a7f9-24a358fcf65e
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=dhcp
IPADDR=192.168.40.110
NETMASK=255.255.255.0
GATEWAY=192.168.40.2
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
HWADDR=00:0C:29:02:55:0F
PREFIX=24
DEFROUTE=yes
NAME="System eth0"
LAST_CONNECT=1591064817

[root@dog network-scripts]# cp ifcfg-eth0 ifcfg-eth0.bak
[root@dog network-scripts]# ls
ifcfg-eth0      ifdown-post    ifup-ippp    ifup-tunnel
ifcfg-eth0.bak  ifdown-ppp     ifup-ipv6    ifup-wireless
ifcfg-lo        ifdown-routes  ifup-isdn    init.ipv6-global
ifdown          ifdown-sit     ifup-plip    net.hotplug
ifdown-bnep     ifdown-tunnel  ifup-plusb   network-functions
ifdown-eth      ifup           ifup-post    network-functions-ipv6
ifdown-ippp     ifup-aliases   ifup-ppp
ifdown-ipv6     ifup-bnep      ifup-routes
ifdown-isdn     ifup-eth       ifup-sit
[root@dog network-scripts]# rm ifcfg-eth0
rm:是否刪除普通文件 "ifcfg-eth0"?y
[root@dog network-scripts]# ls ifcfg*
ifcfg-eth0.bak  ifcfg-lo
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