linux網絡基礎管理

時間 2019-11-20

標籤 linux 網絡基礎管理欄目 Linux 简体版

原文原文鏈接

目錄node

linux網絡基礎管理

@mysql

1. 網卡命名

1.1 傳統網卡命名機制

傳統命名：
以太網eth[0,1,2,...]
wlan[0,1,2,...]linux

1.2 redhat7網卡命名機制

systemd對網絡設備的命名方式：ios

若是Firmware或BIOS爲主板上集成的設備提供的索引信息可用，且可預測，則根據此索引進行命名，例如eno1
若是Firmware或BIOS爲PCI-E擴展槽所提供的索引信息可用，且可預測，則根據此索引進行命名，例如ens1
若是硬件接口的物理位置信息可用，則根據此信息進行命名，例如enp2s0
若是用戶顯式啓動，也可根據MAC地址進行命名，例如enx2387a1dc56
上述均不可用時，則使用傳統命名機制
上述命名機制中，有的須要biosdevname程序的參與。因此必須安裝biosdevname程序且啓用它。nginx

1.3 網絡接口名稱組成格式

基於固件、設備結構、設備類型git

由兩個字母開頭標示固件
以太網網卡以 en 開頭
無線網卡以 wl 開頭
設備結構
o：主板上集成的設備的設備索引號
s：擴展槽的索引號
x：基於MAC地址的命名
p s ：基於物理位置拓撲的命名。如enp2s1，表示PCI總線上第2個總線的第1個插槽的設備索引號
1.4 網卡設備的命名過程
udev，輔助工具程序/lib/udev/rename_device會根據/usr/lib/udev/rules.d/60-net.rules中的信息設定網卡名稱
biosdevname會根據/usr/lib/udev/rules.d/71-biosdevname.rules中的信息設定網卡名稱
經過udev檢測網絡接口設備，根據/usr/lib/udev/rules.d/75-net-description中的變量信息設定網卡名稱 redis

迴歸傳統名

[root@localhost ~]# mv /etc/sysconfig/network-scripts/ifcfg-ens33 /etc/sysconfig/network-scripts/ifcfg-eth0
[root@localhost ~]# ls /etc/sysconfig/network-scripts/ |grep ifcfg-e
ifcfg-eth0
[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0
[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=dhcp
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
UUID=52ed696c-ea51-4509-89b8-cfa4a7f22aee
DEVICE=eth0                                                                         //修改
NAME=eth0                                                                           //修改
ONBOOT=yes


//編輯/etc/default/grub配置文件，在以GRUB_CMDLINE_LINUX開頭的行內rhgb的前面加上net.ifnames=0 biosdevname=0
[root@localhost ~]# vim /etc/default/grub
[root@localhost ~]# cat /etc/default/grub 
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap net.ifnames=0 biosdevname=0 rhgb quiet"
                                                                            |------------添加-----------|
GRUB_DISABLE_RECOVERY="true"

//爲grub2生成其配置文件
[root@localhost ~]# grub2-mkconfig -o /etc/grub2.cfg 
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-693.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-693.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-56592b1fdc854164b8d6f8107bb3caa0
Found initrd image: /boot/initramfs-0-rescue-56592b1fdc854164b8d6f8107bb3caa0.img
done

//重啓生效
[root@localhost ~]# reboot

[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1694sec preferred_lft 1694sec
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever

2. 網絡管理經常使用命令

2.1 ifconfig

//查看當前處於活動狀態的全部網絡接口
[root@localhost ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.213.132  netmask 255.255.255.0  broadcast 192.168.213.255
        inet6 fe80::f6f:62de:73a6:fa93  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:84:06:e4  txqueuelen 1000  (Ethernet)
        RX packets 1582  bytes 141335 (138.0 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 960  bytes 111137 (108.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 68  bytes 5792 (5.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 68  bytes 5792 (5.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

//僅查看eth0網卡狀態      
[root@localhost ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.213.132  netmask 255.255.255.0  broadcast 192.168.213.255
        inet6 fe80::f6f:62de:73a6:fa93  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:84:06:e4  txqueuelen 1000  (Ethernet)
        RX packets 1612  bytes 143825 (140.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 978  bytes 113851 (111.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

//查看全部網卡狀態信息, 包括禁用和啓用
[root@localhost ~]# ifconfig -a
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.213.132  netmask 255.255.255.0  broadcast 192.168.213.255
        inet6 fe80::f6f:62de:73a6:fa93  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:84:06:e4  txqueuelen 1000  (Ethernet)
        RX packets 1657  bytes 147697 (144.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1006  bytes 117125 (114.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 68  bytes 5792 (5.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 68  bytes 5792 (5.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

//關閉 （lo） 接口
[root@localhost ~]# ifconfig lo down
打開網卡（lo）接口
[root@localhost ~]# ifconfig lo up

//網卡配置信息含義以下:

UP: 網卡處於活動狀態
BROADCAST: 支持廣播
RUNNING: 網線已接入
MULTICAST: 支持組播
MTU: 最大傳輸單元(字節),即此接口一次所能傳輸的最大封包

inet: 顯示IPv4地址行
inet6: 顯示IPv6地址行
link/enther: 指設備硬件(MAC)地址
txqueuelen: 傳輸緩存區長度大小
RX packets: 接收的數據包
TX packets: 發送的數據包
errors: 總的收包的錯誤數量
dropped: 因爲各類緣由, 致使拷貝在內存過程當中被丟棄
collisions: 網絡信號衝突狀況, 值不爲0則可能存在網絡故障

2.2 ip

//語法：ip [ OPTIONS ] OBJECT { COMMAND | help }
OBJECT：
    link：網絡接口屬性
    addr：協議地址
    route：路由

//查看IP信息
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1242sec preferred_lft 1242sec
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever

//查看網絡接口全部地址 
[root@localhost ~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:f

//顯示報文統計信息
[root@localhost ~]# ip -s link show
1: lo: <LOOPBACK,UP,LOWER_UP> 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
    RX: bytes  packets  errors  dropped overrun mcast   
    0          0        0       0       0       0       
    TX: bytes  packets  errors  dropped carrier collsns 
    0          0        0       0       0       0       
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    13396      127      0       0       0       0       
    TX: bytes  packets  errors  dropped carrier collsns 
    14967      129      0       0       0       0

//啓用或禁用網絡接口ip link set DEV {up|down}
[root@localhost ~]# ip link set lo down
[root@localhost ~]# ip link set lo up

//ip addr add ADDRESS dev DEV：添加IP地址
[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1429sec preferred_lft 1429sec
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever
[root@localhost ~]# ip addr add 192.168.213.130/24 dev eth0
[root@localhost ~]# ip addr show eth0
[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1287sec preferred_lft 1287sec
    inet 192.168.213.130/24 scope global secondary eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever

//ip addr del ADDRESS dev DEV：刪除IP地址
[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1287sec preferred_lft 1287sec
    inet 192.168.213.130/24 scope global secondary eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever
[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1121sec preferred_lft 1121sec
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever

//ip addr show DEV：查看網絡接口的地址
[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:84:06:e4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.213.132/24 brd 192.168.213.255 scope global dynamic eth0
       valid_lft 1041sec preferred_lft 1041sec
    inet6 fe80::f6f:62de:73a6:fa93/64 scope link 
       valid_lft forever preferred_lft forever

//ip route：routing table management 路由管理                                                    //`在這裏插入代碼片`
//添加路由：ip route add TARGET via GW dev IFACE src SOURCE_IP
    TARGET：
        主機路由：IP
        網絡路由：NETWORK/MASK 
        
//刪除路由：ip route del TARGET
    TARGET：
        主機路由：IP
        網絡路由：NETWORK/MASK
                        
//查看路由：ip route show

//刷新路由表：ip route flush
    [dev IFACE]
    [via PREFIX]

2.3 route

Linux主機之間是使用IP進行通訊, 假設A主機和B主機同在一個網段內且網卡都處於激活狀態, 則A具有和B直接通訊的能力, 但若是A主機和B主機處於兩個不一樣的網段, 則A必須經過路由器才能和B通訊, 路由器屬於IT設備的基礎設施, 每個網段都應該至少有一個網關sql

//查看當前路由表
[root@localhost ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         gateway         0.0.0.0         UG    100    0        0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U     100    0        0 eth0

//以數字方式顯示各主機或端口等相關信息
[root@localhost ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.213.2   0.0.0.0         UG    100    0        0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U     100    0        0 eth0

//增長路由
//語法：route add [-net|-host] target [netmask Nm] [gw Gw]  [[dev] If]

//增長網段路由
[root@localhost ~]# route add -net 192.168.1.0/24 gw 192.168.1.254 dev eth0
[root@localhost ~]# route add -net 0.0.0.0/0 gw 192.168.1.254 dev eth0

//增長主機路由
[root@localhost ~]# route add -host 172.16.12.128 gw 172.16.12.2

//例：
[root@guilai ~]# route add -net 192.168.161.0/24 gw 192.168.213.2 dev eth0
[root@guilai ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.213.2   0.0.0.0         UG    100    0        0 eth0
192.168.161.0   192.168.213.2   255.255.255.0   UG    0      0        0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U     100    0        0 eth0
[root@guilai ~]# route del -net 192.168.161.0/24
[root@guilai ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.213.2   0.0.0.0         UG    100    0        0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U     100    0        0 eth0

//刪除路由
[root@localhost ~]# route del -net 192.168.1.0/24
[root@localhost ~]# route del -net 0.0.0.0 gw 192.168.1.254

2.4 hostname與hostnamectl

生產環境中必須配置主機名,同時主機名也須要遵循必定的規範, 好比:
公有云: 地區-項目-業務-服務-節點-地址
wh-shop-register-nginx-node1-192.168.56.13
wh-med-pay-mysql-master01-192.168.56.11
wh-med-pay-mysql-slave01-192.168.56.12vim

//hostname查看主機名
[root@localhost ~]# hostname
localhost.localdomain

//hostname臨時修改主機名
[root@localhost ~]# hostname tianxiadiyi
[root@localhost ~]# cat /etc/hostname
localhost.localdomain
//注意：修改主機名後須要從新登陸用戶纔會顯示效果

//rhel7系統建議使用hostnamectl修改和查看主機名
//設定永久名稱
[root@localhost ~]# hostnamectl set-hostname guilai
[root@localhost ~]# cat /etc/hostname
guilai

//查看主機信息
[root@localhost ~]# hostnamectl
   Static hostname: guilai
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 56592b1fdc854164b8d6f8107bb3caa0
           Boot ID: 9d806f2ea7c54acbb7f100c0bcce2a18
    Virtualization: vmware
  Operating System: Red Hat Enterprise Linux Server 7.4 (Maipo)
       CPE OS Name: cpe:/o:redhat:enterprise_linux:7.4:GA:server
            Kernel: Linux 3.10.0-693.el7.x86_64
      Architecture: x86-64

注意：
在Linux中以命令方式修改網絡配置只在當前狀態有效，重啓後將失效。故若想使修改的配置重啓後依然有效，則必須編輯配置文件進行配置的修改。緩存

3.網絡相關配置文件

//網絡配置文件：/etc/sysconfig/network
    NETWORKING={yes|no}：設定整個系統是否啓用網絡功能，若設爲no，則不論網卡如何設置都不能使用網絡功能。
    HOSTNAME：設置主機名

3.2 網絡接口配置文件

網絡接口即網卡，其配置文件的路徑是/etc/sysconfig/network-scripts/ifcfg-INTERFACE_NAME

[root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0
TYPE=Ethernet                                                                           //接口類型。常見的接口類型有：Ethernet，Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static                                                                        //引導協議，可選值有｛static｜none｜dhcp｜bootp｝。若是要使用靜態地址，使用static或none均可以
DEFROUTE=yes                                                            //將接口設定爲默認路由[yes|no]
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
UUID=52ed696c-ea51-4509-89b8-cfa4a7f22aee                                               //設備的唯一標識
DEVICE=eth0                                                                             //關聯的設備名稱，要與文件名的後半部"INTERFACE_NAME"保持一致
NAME=eth0                                                                               //鏈接名稱  
ONBOOT=yes                                                                              //在系統引導時是否自動激活此網絡接口，可選值有{ yes ｜ no }                                                            
IPADDR=192.168.213.132                                                                  //固定IP地址
NETMASK=255.255.255.0                                                                   //子網掩碼//子網掩碼                    PREFIX=24也是子網掩碼
GATEWAY=192.168.213.2                                                                   //默認網關
DNS1=192.168.213.2                                                                      //第一個DNS服務器指向，          DNS2 //第二個DNS服務器指向



//網卡配置說明
//參數                    說明
BOOTPROTO=none          //引導協議，可選值有｛static｜none｜dhcp｜bootp｝。若是要使用靜態地址，使用static或none均可以
NM_CONTROLLED           //NM是NetworkManager的簡寫，NM是由RHEL研發的在RHEL6中取代network腳原本實現網絡管理、配置的服務腳本
    //可選值有{ yes ｜ no }
    //此項是設定此網卡是否接受NM控制。CentOS6建議設爲「no」
TYPE                    //接口類型。常見的接口類型有：Ethernet，Bridge
UUID                    //設備的唯一標識
HWADDR                  //硬件地址，要與硬件中的地址保持一致，可省
IPADDR=172.16.12.130    //固定IP地址
PREFIX=24               //子網掩碼
NETMASK=255.255.255.0   //子網掩碼
GATEWAY=172.16.12.2     //默認網關
DNS1=172.16.12.2        //第一個DNS服務器指向
DNS2                    //第二個DNS服務器指向
DNS3                    //第三個DNS服務器指向
DEVICE=eth1             //關聯的設備名稱，要與文件名的後半部"INTERFACE_NAME"保持一致  
NAME="eth1"             //鏈接名稱
ONBOOT=yes              //在系統引導時是否自動激活此網絡接口，可選值有{ yes ｜ no }
DEFROUTE=yes            //將接口設定爲默認路由[yes|no]
USERCTL={yes|no}        //是否容許普通用戶控制此接口的啓用與禁用
PEERDNS={yes|no}        //是否在BOOTPROTO爲dhcp時接受由dhcp服務器指定的DNS地址，此項設爲yes時得到的DNS地址將直接覆蓋至/etc/resolv.conf文件中

3.3路由配置文件

路由配置文件的路徑是/etc/sysconfig/network-scripts/route-INTERFACE_NAME

//添加格式一：DEST via NEXTHOP
[root@localhost ~]# vi /etc/sysconfig/network-scripts/route-ens33                       //用vi生成編輯
172.16.12.0/24 via 172.16.12.2
                
//添加格式二：
[root@localhost ~]# vi /etc/sysconfig/network-scripts/route-ens33
ADDRESS0=172.16.12.0
NETMASK0=255.255.255.0
GATEWAY0=172.16.12.2

3.4DNS配置文件

DNS配置文件的路徑是/etc/resolv.conf

[root@localhost ~]# vi /etc/resolv.conf
nameserver DNS_IP_1
nameserver DNS_IP_2
nameserver DNS_IP_3

不必配置這個，若是在vi /etc/sysconfig/network-scripts/ifcfg-eth0

4. NetworkManager管理網絡

RHEL/CentOS7系統默認使用NetworkManager來提供網絡服務，這是一種動態管理網絡配置的守護進程，可以讓網絡設備保持鏈接狀態。
NetworkManager提供的命令行和圖形配置工具對網絡進行設定, 設定保存的配置文件在/etc/sysconfig/network-scripts目錄下, 工具備 nmcli, nmtui, nm-connect-editor

device物理設備, 例如 ens33,enp2s0,virbr0,team0
connection鏈接設置, 具體網絡配置方案

1.不一樣的網絡鏈接配置能夠應用到相同的物理設備，但物理設備同一時間只能應用其中某個網絡鏈接
2.針對物理網絡接口, 設定不一樣的網絡鏈接, 在不一樣的使用環境中激活相應的網絡鏈接，就能夠實現網絡配置信息的自動切換了

使用nmcli命令查看設備以及鏈接狀況

//查看設備狀態
[root@guilai ~]# nmcli device
設備  類型      狀態    鏈接 
eth0  ethernet  鏈接的  eth0 
lo    loopback  未託管  --   

//查看指定設備的詳細狀態
[root@guilai ~]# nmcli device show eth0
GENERAL.設備:                           eth0
GENERAL.類型:                           ethernet
GENERAL.硬盤:                           00:0C:29:84:06:E4
GENERAL.MTU:                            1500
GENERAL.狀態:                           100 (鏈接的)
GENERAL.鏈接:                           eth0
GENERAL.鏈接路徑:                       /org/freedesktop/NetworkManager/ActiveConnection/2
WIRED-PROPERTIES.載波:                  開
IP4.地址[1]:                            192.168.213.132/24
IP4.網關:                               192.168.213.2
IP4.DNS[1]:                             192.168.213.2
IP6.地址[1]:                            fe80::f6f:62de:73a6:fa93/64
IP6.網關:                               --

//查看鏈接狀態            //查看全部活動的鏈接
[root@guilai ~]# nmcli connection
名稱  UUID                                  類型            設備 
eth0  52ed696c-ea51-4509-89b8-cfa4a7f22aee  802-3-ethernet  eth0 

//查看指定設備鏈接的詳細狀況
[root@guilai ~]# nmcli connection show eth0
connection.id:                          eth0
connection.uuid:                        52ed696c-ea51-4509-89b8-cfa4a7f22aee
connection.stable-id:                   --
connection.interface-name:              eth0
connection.type:                        802-3-ethernet
connection.autoconnect:                 yes
connection.autoconnect-priority:        0
connection.autoconnect-retries:         -1 (默認)
connection.timestamp:                   1570532473
connection.read-only:                   no
connection.permissions:                 --
connection.zone:                        --
.....................

5. 使用原生network管理網絡

CentOS/RHEL的網絡配置文件默認目錄爲/etc/sysconfig/network-scripts
默認第一塊物理網卡配置文件爲ifcfg-eth0, 若是有第二塊物理網卡, 配置文件則爲ifcfg-eth1以此類推。注意: 若是新增物理網卡沒有配置文件，可選擇複製系統默認的進行修改。

//設置NetworkManger開機不啓動, 同時中止NetworkManger服務
[root@localhost ~]# systemctl disable NetworkManager
[root@localhost ~]# systemctl stop NetworkManager

//添加一塊物理網卡, 而後新增網絡鏈接配置文件
//複製配置eth0配置文件爲eth1
/添加一塊物理網卡, 而後新增網絡鏈接配置文件
//複製配置eth0配置文件爲eth1
[root@localhost ~]# cp /etc/sysconfig/network-scripts/{ifcfg-eth0,ifcfg-eth1}
//編輯網卡配置文件
[root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth1
TYPE=Ethernet
BOOTPROTO=static
NAME=eth1
UUID=03be31f5-a3c1-4f8d-88b3-aea6e85c869f
DEVICE=eth1
NM_CONTROLLED=no
ONBOOT=yes
IPADDR=172.16.12.130
NETMASK=255.255.255.0
GATEWAY=172.16.12.2
DNS1=172.16.12.2

//重啓network網絡服務加載網絡並設置開機啓動
[root@localhost ~]# systemctl restart network
[root@localhost ~]# systemctl enable network

6.網絡檢測工具與故障排查

6.1 ping

ping命令的目的在於測試另外一臺主機是否可達, 若是ping不到某臺主機,就說明對方主機已經出現了問題, 可是不排除因爲鏈路中的防火牆、ping被丟棄等緣由形成ping不通的狀況

//ping命令經常使用選項：
    -c 指定ping的次數
    -i 指定ping包的發送間隔
    -w 若是ping沒有迴應, 則在指定超時時間後退出
 
 // ping 5 次
[root@guilai ~]# ping -c 5 www.baidu.com
PING www.a.shifen.com (182.61.200.6) 56(84) bytes of data.
64 bytes from 182.61.200.6 (182.61.200.6): icmp_seq=1 ttl=128 time=21.8 ms
64 bytes from 182.61.200.6 (182.61.200.6): icmp_seq=2 ttl=128 time=27.6 ms
64 bytes from 182.61.200.6 (182.61.200.6): icmp_seq=3 ttl=128 time=47.5 ms
64 bytes from 182.61.200.6 (182.61.200.6): icmp_seq=4 ttl=128 time=22.4 ms
64 bytes from 182.61.200.6 (182.61.200.6): icmp_seq=5 ttl=128 time=21.9 ms

--- www.a.shifen.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4008ms
rtt min/avg/max/mdev = 21.837/28.289/47.585/9.893 ms

//每0.1秒ping一次
[root@guilai ~]# ping -i 0.1 www.baidu.com

6.2 host與nslookup

host/nslookup命令用於查詢DNS記錄

host/nslookup命令用於查詢DNS記錄
[root@guilai ~]# host www.baidu.com
www.baidu.com is an alias for www.a.shifen.com.
www.a.shifen.com has address 182.61.200.7
www.a.shifen.com has address 182.61.200.6```



[root@guilai ~]# nslookup www.baidu.com
Server:     192.168.213.2
Address:    192.168.213.2#53

Non-authoritative answer:
www.baidu.com   canonical name = www.a.shifen.com.
Name:   www.a.shifen.com
Address: 182.61.200.6
Name:   www.a.shifen.com
Address: 182.61.200.7

yum provides *bin/nslookup 來查看該命令須要安裝什麼包

6.3 traceroute

traceroute命令用於路由跟蹤, 檢測網絡故障出如今ISP運營商或是對端服務沒法響應

[root@guilai ~]# traceroute www.baidu.com
traceroute to www.baidu.com (182.61.200.7), 30 hops max, 60 byte packets
 1  gateway (192.168.213.2)  0.097 ms  0.066 ms  0.088 ms
 2  * * *
 3  * * *
 4  * * *
 5  * * *
 6  * * *
 7  * * *
 8  * * *
 9  * * *

6.4 netstat

netstat用於查看網絡狀態

//顯示路由表
[root@seancheng ~]# netstat -r
[root@guilai ~]# netstat -r
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
default         gateway         0.0.0.0         UG        0 0          0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U         0 0          0 eth0


//以數字方式顯示路由表
[root@seancheng ~]# netstat -rn 
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.213.2   0.0.0.0         UG        0 0          0 eth0
192.168.213.0   0.0.0.0         255.255.255.0   U         0 0          0 eth0

//顯示創建的tcp鏈接
[root@seancheng ~]# netstat -t
[root@guilai ~]# netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0     52 guilai:ssh              192.168.213.1:51255     ESTABLISHED

//顯示udp鏈接
[root@seancheng ~]# netstat -u
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State 



//顯示監聽狀態的鏈接
[root@seancheng ~]# netstat -l
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN     
tcp        0      0 localhost:smtp          0.0.0.0:*               LISTEN     
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN     
tcp6       0      0 localhost:smtp          [::]:*                  LISTEN     
udp        0      0 localhost:323           0.0.0.0:*                          
udp6       0      0 localhost:323           [::]:*                             
raw6       0      0 [::]:ipv6-icmp          [::]:*                  7          
Active UNIX domain sockets (only servers)
Proto RefCnt Flags       Type       State         I-Node   Path
unix  2      [ ACC ]     STREAM     LISTENING     19870    private/trace
unix  2      [ ACC ]     STREAM     LISTENING     19873    private/verify
unix  2      [ ACC ]     STREAM     LISTENING     19879    private/proxymap
unix  2      [ ACC ]     SEQPACKET  LISTENING     14350    /run/udev/control
unix  2      [ ACC ]     STREAM     LISTENING     19882    private/proxywrite
......

//顯示監聽指定的套接字的進程的進程號及進程名
[root@seancheng ~]# netstat -p
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0     52 guilai:ssh              192.168.213.1:51255     ESTABLISHED 1409/sshd: root@pts 
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node   PID/Program name     Path
unix  2      [ ]         DGRAM                    14373    1/systemd            /run/systemd/shutdownd
unix  2      [ ]         DGRAM                    15922    767/chronyd          /var/run/chrony/chronyd.sock
unix  2      [ ]         DGRAM                    9170     1/systemd            /run/systemd/notify
unix  2      [ ]         DGRAM                    9172     1/systemd            /run/systemd/cgroups-agent
unix  5      [ ]         DGRAM                    9183     1/systemd            /run/systemd/journal/socket
unix  16     [ ]         DGRAM                    9185     1/systemd            /dev/log
unix  3      [ ]         DGRAM                    14889    594/systemd-udevd    
unix  3      [ ]         STREAM     CONNECTED     16123    781/crond            
unix  3      [ ]         STREAM     CONNECTED     19848    1342/master          
.........

/顯示全部狀態的鏈接
[root@seancheng ~]# netstat -a
[root@guilai ~]# netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN     
tcp        0      0 localhost:smtp          0.0.0.0:*               LISTEN     
tcp        0     52 guilai:ssh              192.168.213.1:51255     ESTABLISHED
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN     
tcp6       0      0 localhost:smtp          [::]:*                  LISTEN     
udp        0      0 guilai:48786            makaki.miuku.net:ntp    ESTABLISHED
udp        0      0 localhost:323           0.0.0.0:*                          
udp6       0      0 localhost:323           [::]:*                             
raw6       0      0 [::]:ipv6-icmp          [::]:*                  7          
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node   Path
unix  2      [ ACC ]     STREAM     LISTENING     19870    private/trace
unix  2      [ ACC ]     STREAM     LISTENING     19873    private/verify
unix  2      [ ACC ]     STREAM     LISTENING     19879    private/proxymap
unix  2      [ ACC ]     SEQPACKET  LISTENING     14350    /run/udev/control
unix  2      [ ACC ]     STREAM     LISTENING     19882    private/proxywrite
unix  2      [ ACC ]     STREAM     LISTENING     19885    private/smtp
unix  2      [ ACC ]     STREAM     LISTENING     19888    private/relay
unix  2      [ ACC ]     STREAM     LISTENING     19894    private/error
unix  2      [ ]         DGRAM                    14373    /run/systemd/shutdownd
..................






//經常使用選項
    -antlp

[root@seancheng ~]# netstat -antlp
[root@guilai ~]# netstat -antlp
Active Internet connections (servers and established)
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      1115/sshd           
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1342/master         
tcp        0     52 192.168.213.132:22      192.168.213.1:51255     ESTABLISHED 1409/sshd: root@pts 
tcp6       0      0 :::22                   :::*                    LISTEN      1115/sshd           
tcp6       0      0 ::1:25                  :::*                    LISTEN      1342/master

6.5 ss

ss是一種網絡狀態查看工具，取代netstat

//語法：ss [options] [ FILTER ]
//經常使用的options：
    -t：tcp協議相關
    -u：udp協議相關
    -w：裸套接字相關
    -x：unix套接字相關
    -l：listen狀態的鏈接
    -a：全部
    -n：數字格式
    -p：相關的程序及pid
    -e：擴展的信息
    -m：內存用量
    -o：顯示計時器信息


//常見的FILTER：
    FILTER := [ state TCP-STATE ] [ EXPRESSION ]
    如：ss -tan state ESTABLISHED
                        
//常見的state：
    //tcp finite state machine：有限狀態機
        LISTEN：監聽
        ESTABLISHED：已創建的鏈接
        
    //EXPRESSION：
        dport =
        sport =
        示例：'( dport = :ssh or sport = :ssh)'，此處的ssh也即服務名可使用其對應的端口號代替，等號兩邊必須有空格
        



//經常使用組合：
[root@seancheng ~]# ss -tan
[root@guilai ~]# 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                 192.168.213.132:22                              192.168.213.1:51255              
LISTEN     0      128                            :::22                                         :::*                  
LISTEN     0      100                           ::1:25                                         :::*       

[root@seancheng ~]# ss -tanl
State      Recv-Q Send-Q              Local Address:Port                             Peer Address:Port              
LISTEN     0      128                             *:22                                          *:*                  
LISTEN     0      100                     127.0.0.1:25                                          *:*                  
LISTEN     0      128                            :::22                                         :::*                  
LISTEN     0      100                           ::1:25                                         :::*          


[root@seancheng ~]# ss -antlp
State      Recv-Q Send-Q              Local Address:Port                             Peer Address:Port              
LISTEN     0      128                             *:22                                          *:*                   users:(("sshd",pid=1115,fd=3))
LISTEN     0      100                     127.0.0.1:25                                          *:*                   users:(("master",pid=1342,fd=13))
LISTEN     0      128                            :::22                                         :::*                   users:(("sshd",pid=1115,fd=4))
LISTEN     0      100                           ::1:25                                         :::*                   users:(("master",pid=1342,fd=14))



[root@seancheng ~]# ss -anu

State      Recv-Q Send-Q              Local Address:Port                             Peer Address:Port              
UNCONN     0      0                       127.0.0.1:323                                         *:*                  
UNCONN     0      0                             ::1:323                                        :::*

常見端口

服務	端口號
http	80/tcp
https	443/tcp
ssh	22/tcp
ftp	20,21/tcp
mysql	3306/tcp
rsync	873/rsync
redis	6379/tcp
Telnet	23/tcp
TFTP	69/udp

6.6 網絡故障排查

網絡故障分爲硬件/軟件故障
網卡損壞
鏈路故障
網卡驅動不兼容
網絡排查思路
ping本地迴環口, 肯定本機TCP/IP協議棧是否正常
ping本機IP地址, 肯定本地設備以及驅動是否正常
ping同網段主機, 肯定二層網絡是否正常工做
ping網關地址, 肯定本地與網絡是否正常
ping公網地址, 肯定本地路由是否正常
ping公網域名, 肯定DNS客戶端是否正常
服務故障排查思路
使用telnet檢測端口是否開放
檢查服務端防火牆以及SElinux
檢查相應的權限是否配置正常
檢查日誌是否有異常
檢查完畢後持續測試

建議:
全部的排查思路都從OSI七層模型由下往上逐一進行排查(學會看日誌)

做業

1.如何查看系統中每一個ip的鏈接數

[root@guilai ~]# netstat -na |awk '{print $5}'|awk -F: '{print $1}'|grep [[:digit:]]
0.0.0.0
0.0.0.0
192.168.213.1
0.0.0.0

2.請列出下列服務使用的端口,http,ftp,ssh,telnet,mysql,dns

服務	端口號
http	80/tcp
ssh	22/tcp
ftp	20,21/tcp
telent	23/tcp
mysql	3306/tcp
dns	53udp

3.如何在虛擬機上新增長一塊網卡，並配置IP爲172.16.0.10，指定網關爲172.16.0.1

[root@guilai ~]# cd /etc/sysconfig/network-scripts/

[root@guilai network-scripts]# systemctl disable NetworkManager
Removed symlink /etc/systemd/system/multi-user.target.wants/NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service.
[root@guilai network-scripts]# systemctl stop NetworkManager

[root@guilai network-scripts]# cp ifcfg-eth0 ifcfg-eth1
[root@guilai network-scripts]# vim ifcfg-eth1
[root@guilai network-scripts]# cat ifcfg-eth1
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
UUID=52ed696c-ea51-4509-89b8-cfa4a7f22aee
DEVICE=eth1
NAME=eth1
ONBOOT=yes
IPADDR=172.16.0.10
NETMASK=255.255.255.0
GATEWAY=172.16.0.1
DNS1=192.168.213.2

[root@guilai network-scripts]# systemctl enable NetworkManager
[root@guilai network-scripts]# systemctl start NetworkManager
[root@guilai network-scripts]# systemctl restart network

[root@guilai network-scripts]# ifconfig eth1
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.16.0.10  netmask 255.255.255.0  broadcast 172.16.0.255
        inet6 fe80::f35b:4df0:b42a:4fe9  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:84:06:ee  txqueuelen 1000  (Ethernet)
        RX packets 47  bytes 4035 (3.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 18  bytes 1284 (1.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

4.詳細描述dns解析過程，以訪問www.baidu.com爲例

訪問www.baidu.com 通過dns域名解析返回www.baidu.com的ip地址

5.如何查看系統中運行了多少個進程

[root@guilai ~]# ps -ef >a  
[root@guilai ~]# cat -n a
用最大行數減一

6.如何查看系統中啓動了哪些端口

[root@guilai ~]# netstat -an

7.如何查看是否開啓80端口，及查看sshd進程是否存在

[root@guilai ~]# netstat -anp |grep ssh


安裝lsof
[root@guilai ~]# lsof -i :80

[root@guilai ~]# lsof -i :ssh

8.列出全部處於監聽狀態的tcp端口

[root@guilai ~]# netstat -ltpnu
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      1238/sshd           
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1472/master         
tcp6       0      0 :::22                   :::*                    LISTEN      1238/sshd           
tcp6       0      0 ::1:25                  :::*                    LISTEN      1472/master         
udp        0      0 127.0.0.1:323           0.0.0.0:*                           765/chronyd         
udp6       0      0 ::1:323                 :::*                                765/chronyd

9.查看全部的端口信息, 包括 PID 和進程名稱