Linux网络管理

Posted on Waline:

Linux网络管理

一直觉得Linux网络管理相关的命令繁杂，今天就试着整理一下吧。

网络是块大内容，这里仅把Linux网络相关的命令做整理，网络相关的知识暂不作整理。

一、查网络基本配置

1.1 查ip

有多种方式查系统的 IP 地址

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ip address
ifconfig
ifconfig 网卡名
hostname -I

可简写成 ip a，ip addr 等

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# ip address
[root@centos7 ~]# ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:bc:5e:c7 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.10/24 brd 192.168.10.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::6e66:1e1e:5c59:86dc/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@centos7 ~]# 

# ifconfig
[root@centos7 ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.10.10  netmask 255.255.255.0  broadcast 192.168.10.255
        inet6 fe80::6e66:1e1e:5c59:86dc  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:bc:5e:c7  txqueuelen 1000  (Ethernet)
        RX packets 193591  bytes 53716386 (51.2 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 309342  bytes 221017197 (210.7 MiB)
        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 1000  (Local Loopback)
        RX packets 20  bytes 4414 (4.3 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 20  bytes 4414 (4.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@centos7 ~]# 

# hostname -I
[root@centos7 ~]# hostname -I
192.168.10.10 
[root@centos7 ~]# 

# ifconfig 网卡名
[root@centos7 ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.10.10  netmask 255.255.255.0  broadcast 192.168.10.255
        inet6 fe80::f1b0:3c25:52f9:4811  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:bc:5e:c7  txqueuelen 1000  (Ethernet)
        RX packets 201105  bytes 60075622 (57.2 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 313473  bytes 221592583 (211.3 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@centos7 ~]#

1.2 查路由及网关

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ip route
ip route show
route -n
netstat -rn

可简写成 ip r 等。

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# ip route
[root@centos7 ~]# ip route
default via 192.168.10.2 dev ens33 proto static metric 100 
192.168.10.0/24 dev ens33 proto kernel scope link src 192.168.10.10 metric 100 
[root@centos7 ~]# 

# route -n
[root@centos7 ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.10.2    0.0.0.0         UG    100    0        0 ens33
192.168.10.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
[root@centos7 ~]# 

# netstat -rn
[root@centos7 ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.10.2    0.0.0.0         UG        0 0          0 ens33
192.168.10.0    0.0.0.0         255.255.255.0   U         0 0          0 ens33
[root@centos7 ~]#

1.3 查DNS服务器

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cat /etc/resolv.conf
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[root@centos7 ~]# cat /etc/resolv.conf
# Generated by NetworkManager
search server.templaate
nameserver 1.1.1.1
[root@centos7 ~]#

Ubuntu 下也可以使用

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resolvectl status
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root@ubuntu24server:~# resolvectl status
Global
         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub

Link 2 (ens33)
    Current Scopes: DNS
         Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
       DNS Servers: 1.1.1.1 8.8.8.8
root@ubuntu24server:~#

二、NetworkManager（redhat）

NetworkManager 是 Redhat 系Linux 的网络管理守护进程，负责监控和配置系统网络。

配置文件在 /etc/sysconfig/network-scripts 下，同时衍生出 nmcli、nmtui 两种工具来对网络进行配置。

其中，nmcli 是命令行工具，nmtui 是文本图形化工具。本质都是对配置文件的修改。

2.1 nmcli

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[root@centos7 ~]# nmcli 
agent       connection  device      general     help        monitor     networking  radio       
[root@centos7 ~]# nmcli

可以看到主要配置就两块内容，

  • device 网卡设备相关的配置
  • connection 逻辑地址相关的配置

2.1.1 device

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nmcli device status
nmcli device show
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[root@centos7 ~]# nmcli device status
DEVICE  TYPE      STATE      CONNECTION 
ens33   ethernet  connected  ens33      
lo      loopback  unmanaged  --         
[root@centos7 ~]# nmcli device 
connect     delete      disconnect  help        lldp        modify      monitor     reapply     set         show        status      wifi
[root@centos7 ~]# nmcli device show 
GENERAL.DEVICE:                         ens33
GENERAL.TYPE:                           ethernet
GENERAL.HWADDR:                         00:0C:29:BC:5E:C7
GENERAL.MTU:                            1500
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     ens33
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/12
WIRED-PROPERTIES.CARRIER:               on
IP4.ADDRESS[1]:                         192.168.10.10/24
IP4.GATEWAY:                            192.168.10.2
IP4.ROUTE[1]:                           dst = 192.168.10.0/24, nh = 0.0.0.0, mt = 100
IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 192.168.10.2, mt = 100
IP4.DNS[1]:                             1.1.1.1
IP6.ADDRESS[1]:                         fe80::6e66:1e1e:5c59:86dc/64
IP6.GATEWAY:                            --
IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255

GENERAL.DEVICE:                         lo
GENERAL.TYPE:                           loopback
GENERAL.HWADDR:                         00:00:00:00:00:00
GENERAL.MTU:                            65536
GENERAL.STATE:                          10 (unmanaged)
GENERAL.CONNECTION:                     --
GENERAL.CON-PATH:                       --
IP4.ADDRESS[1]:                         127.0.0.1/8
IP4.GATEWAY:                            --
IP6.ADDRESS[1]:                         ::1/128
IP6.GATEWAY:                            --
[root@centos7 ~]#

2.1.2 connection

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[root@centos7 ~]# nmcli connection 
add      clone    delete   down     edit     export   help     import   load     modify   monitor  reload   show     up       
[root@centos7 ~]# nmcli connection

connection 可简写为 con ，主要的子选项

  • 增，add
  • 删，delete
  • 改，modify
  • 查，show
  • 开，up
  • 关，down
  1. 创建一个连接，命名为 zhuzhuxia ，常见的一些静态配置。
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nmcli connection add con-name 连接名 type 连接类型 ipv4.method 方法 ipv4.addresses ip地址1,ip地址2 ipv4.gateway 网关 ipv4.dns dns1,dns2 ifname 网卡 
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[root@centos7 ~]# nmcli connection add con-name zhuzhuxia type ethernet ipv4.method manual ipv4.addresses 192.168.10.10/24,192.168.10.109/24 ipv4.gateway 192.168.10.2 ipv4.dns 1.1.1.1,8.8.8.8 ifname ens33 autoconnect yes 
Connection 'zhuzhuxia' (74ffd674-2ca3-478d-a5dd-d8d7803d0e50) successfully added.
[root@centos7 ~]#
  1. 启用连接
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nmcli connection up 连接名称 
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[root@centos7 ~]# nmcli connection up 
ens33      filename   help       id         path       uuid       zhuzhuxia  

# 启用猪猪侠
[root@centos7 ~]# nmcli connection up zhuzhuxia 
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/18)
[root@centos7 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:bc:5e:c7 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.10/24 brd 192.168.10.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.10.109/24 brd 192.168.10.255 scope global secondary noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::f1b0:3c25:52f9:4811/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@centos7 ~]#
  1. 修改一个连接的配置，已经激活的连接需要重新 down –> up。 reload 不会生效。
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nmcli connection modify 连接名 配置项 参数
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[root@centos7 ~]# nmcli connection modify zhuzhuxia ipv4.addresses 192.168.10.10/24,192.168.10.11nmcli connection up 连接名

2.2 nmtui

没什么可说的，easy。可视化页面配置即可。

nmtui界面

2.3 配置文件

直接修改 /etc/sysconfig/network-scripts 下的配置文件即可。

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[root@centos7 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens33 
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
UUID="e10728d1-4a6e-4233-9aca-c44c04268b5d"
DEVICE="ens33"
ONBOOT="yes"
IPADDR="192.168.10.10"
PREFIX="24"
GATEWAY="192.168.10.2"
DNS1="1.1.1.1"
IPV6_PRIVACY="no"
[root@centos7 ~]#
  • IPADDR ip地址
  • PREFIX 子网掩码
  • GATEWAY 网关
  • DNS1 DNS服务器
  • BOOTPROTO dhcp、static、none
  • ONBOOT 开机自启

修改配置后需要重启网络

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[root@centos7 ~]# systemctl restart network
[root@centos7 ~]#

三、netplan（ubuntu）

从 17.10 版本开始，引入 netplan 作为网络配置工具，底层使用 systemd-networkd 或 Network-Manager。netplan 使用yaml 配置文件来管理网络。配置文件在 /etc/netplan 下。

ubuntu 分为 Serevr 服务器版本、Desktop 桌面版本。

  • Server 版本使用 systemd-networkd 管理网络；

  • Desktop 版本使用 Network-Manager 管理网络。

总之 netplan 可以生成配置文件，交给底层服务，实现大一统。

3.1 配置文件

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root@ubuntu24server:~# cat /etc/netplan/50-cloud-init.yaml 
network:
  version: 2
  ethernets:
    ens33:
      addresses:
      - "192.168.10.20/24"
      nameservers:
        addresses:
        - 1.1.1.1
        - 8.8.8.8
        search: []
      routes:
      - to: "default"
        via: "192.168.10.2"
root@ubuntu24server:~#

静态ip较完整的配置

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network:
  version: 2
  renderer: networkd
  ethernets:
    ens33:
      dhcp4: no
      addresses: [192.168.92.200/24]
      routes:
        - to: default
          via: 192.168.92.2
      nameservers:
        addresses:
          - 8.8.8.8
          - 114.114.114.114
	  optional: true

3.2 启用

  1. 调试，如果有问题120秒后会回退。
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netplan try
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root@ubuntu24server:~# netplan try
Do you want to keep these settings?


Press ENTER before the timeout to accept the new configuration


Changes will revert in 115 seconds

  1. 直接应用
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netplan apply

四、其它网络相关的命令

4.1 ping

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ping 域名或IP
  • -c 发几次包，Linux默认一直发。windwos 不可用
  • -4 强制使用 ipv4
  • -6 强制使用 ipv6
  • -t 在windows 上一直发送

4.2ip 命令

ifconfig 已经标记为过时，已经被 ip 命令取代。

  1. 查看网络信息
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ip addr
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[root@centos7 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:bc:5e:c7 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.10/24 brd 192.168.10.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.10.111/24 brd 192.168.10.255 scope global secondary noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.10.112/24 brd 192.168.10.255 scope global secondary ens33:1
       valid_lft forever preferred_lft forever
    inet6 fe80::f1b0:3c25:52f9:4811/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@centos7 ~]#
  1. 启停网卡
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ip link set 网卡 up
ip link set 网卡 down
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[root@centos7 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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
[root@centos7 ~]# 

# 停用网卡
[root@centos7 ~]# ip link set lo down 
[root@centos7 ~]# ip addr show lo
1: lo: <LOOPBACK> mtu 65536 qdisc noqueue state DOWN group default qlen 1000
    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
[root@centos7 ~]# 

# 启用网卡
[root@centos7 ~]# ip link set lo up
[root@centos7 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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
[root@centos7 ~]#
  1. 设置临时 ip 地址，重启就会失效
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ip addr add ip地址 dev 网卡
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[root@centos7 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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
[root@centos7 ~]# 

# 添加临时IP地址
[root@centos7 ~]# ip addr add 10.0.0.10/24 dev lo
[root@centos7 ~]# 
[root@centos7 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    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
    inet 10.0.0.10/24 scope global lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
[root@centos7 ~]#

4.3 连接状态-netstat - ss

用于查看网络连接的命令。

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netstat 选项
  • -l 显示监听的端口
  • -a 显示所有状态的端口
  • t 显示TCP 的连接
  • u 显示UDP 的连接
  • p 显示进程的名称
  • n 不对端口号进行解释，显示数字端口号
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netstat -antp | head
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[root@centos7 ~]# netstat -antp | head
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      688/rpcbind         
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      942/sshd            
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1064/master         
tcp        0     36 192.168.10.10:22        192.168.10.1:3140       ESTABLISHED 1194/sshd: root@pts 
tcp6       0      0 :::111                  :::*                    LISTEN      688/rpcbind         
tcp6       0      0 :::22                   :::*                    LISTEN      942/sshd            
tcp6       0      0 ::1:25                  :::*                    LISTEN      1064/master         
[root@centos7 ~]#

ss 占用内存更小，用法一样，显示不如 netstat 友好。

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ss -antp | head
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[root@centos7 ~]# ss -antp | head
State      Recv-Q Send-Q	Local Address:Port	Peer Address:Port              
LISTEN     0      128		*:111				*:*					users:(("rpcbind",pid=688,fd=8))
LISTEN     0      128		*:22				*:*					users:(("sshd",pid=942,fd=3))
LISTEN     0      100		127.0.0.1:25		*:*					users:(("master",pid=1064,fd=13))
ESTAB      0      0			192.168.10.10:22	192.168.10.1:3140	users:(("sshd",pid=1194,fd=3))
LISTEN     0      128		[::]:111			[::]:*				users:(("rpcbind",pid=688,fd=11))
LISTEN     0      128		[::]:22				[::]:*				users:(("sshd",pid=942,fd=4))
LISTEN     0      100		[::1]:25			[::]:*				users:(("master",pid=1064,fd=14))
[root@centos7 ~]#

4.4 域名解析-nslookup

4.4.1 使用

nslookup 是一个DNS 解析的命令，用于把域名解析为 IP地址。

安装

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yum install -y bind-utils

使用

  1. 直接查询
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nslookup 域名 DNS服务器
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[root@centos7 ~]# nslookup bravexist.cn 1.1.1.1
Server:         1.1.1.1
Address:        1.1.1.1#53

Non-authoritative answer:
Name:   bravexist.cn
Address: 104.21.67.121
Name:   bravexist.cn
Address: 172.67.221.229
Name:   bravexist.cn
Address: 2606:4700:3031::ac43:dde5
Name:   bravexist.cn
Address: 2606:4700:3035::6815:4379

[root@centos7 ~]#
  1. 交互式界面查询
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nslookup
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[root@centos7 ~]# nslookup
> bravexist.cn
Server:         1.1.1.1
Address:        1.1.1.1#53

Non-authoritative answer:
Name:   bravexist.cn
Address: 104.21.67.121
Name:   bravexist.cn
Address: 172.67.221.229
Name:   bravexist.cn
Address: 2606:4700:3031::ac43:dde5
Name:   bravexist.cn
Address: 2606:4700:3035::6815:4379
>
  1. 查询权威DNS服务器，默认都不是权威DNS服务器应答
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nslookup -type=解析类型 域名
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# 查询权威服务器
[root@centos7 ~]# nslookup -type=ns bravexist.cn
Server:         1.1.1.1
Address:        1.1.1.1#53

Non-authoritative answer:
bravexist.cn    nameserver = diva.ns.cloudflare.com.
bravexist.cn    nameserver = james.ns.cloudflare.com.

Authoritative answers can be found from:

[root@centos7 ~]# 

# 从权威DNS查询
[root@centos7 ~]# nslookup bravexist.cn diva.ns.cloudflare.com.
Server:         diva.ns.cloudflare.com.
Address:        173.245.58.97#53

Name:   bravexist.cn
Address: 104.21.67.121
Name:   bravexist.cn
Address: 172.67.221.229
Name:   bravexist.cn
Address: 2606:4700:3035::6815:4379
Name:   bravexist.cn
Address: 2606:4700:3031::ac43:dde5

[root@centos7 ~]#

4.4.2同类命令-dig-host

  • dig
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[root@centos7 ~]# dig bravexist.cn

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.16 <<>> bravexist.cn
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53809
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;bravexist.cn.                  IN      A

;; ANSWER SECTION:
bravexist.cn.           300     IN      A       104.21.67.121
bravexist.cn.           300     IN      A       172.67.221.229

;; Query time: 346 msec
;; SERVER: 1.1.1.1#53(1.1.1.1)
;; WHEN: Tue Oct 07 13:11:17 CST 2025
;; MSG SIZE  rcvd: 73

[root@centos7 ~]#
  • host
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[root@centos7 ~]# host bravexist.cn
bravexist.cn has address 104.21.67.121
bravexist.cn has address 172.67.221.229
bravexist.cn has IPv6 address 2606:4700:3031::ac43:dde5
bravexist.cn has IPv6 address 2606:4700:3035::6815:4379
bravexist.cn mail is handled by 1 mx1.larksuite.com.
bravexist.cn mail is handled by 5 mx2.larksuite.com.
bravexist.cn mail is handled by 10 mx3.larksuite.com.
[root@centos7 ~]#

4.5路由追踪命令-traceroute

安装

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yum install -y traceroute

使用

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traceroute 域名或IP
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[root@centos7 ~]# traceroute bravexist.cn
traceroute to bravexist.cn (104.21.67.121), 30 hops max, 60 byte packets
 1  gateway (192.168.10.2)  0.081 ms  0.035 ms  0.086 ms
 2  * * *
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30  * * *
[root@centos7 ~]#

4.6 端口测试-telnet-nmap

4.6.1 安装

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yum install nmap telnet -y

4.6.2 使用

telnet

telnet 因为是明文协议，早已经不安全，不推荐使用，但是起端口测试功能依旧很好用。

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telnet ip或域名 端口号

能进去说明端口开放，不能进去可能被防火墙等中间设备拦截了，无法证明是关闭的。

  • 开放
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[root@centos7 ~]# telnet bravexist.cn 80
Trying 104.21.67.121...
Connected to bravexist.cn.
Escape character is '^]'.
  • 关闭或被屏蔽
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[root@centos7 ~]# telnet 192.168.10.10
Trying 192.168.10.10...
telnet: connect to address 192.168.10.10: Connection refused
[root@centos7 ~]#

nmap

nmap 是一款开源免费的软件，用于网络端口测试。这里只记录一下最基本的用法，详细用法有机会单独开一篇。

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nmap 域名或IP

默认会探测常见的 1000个端口号。

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[root@centos7 ~]# nmap bravexist.cn

Starting Nmap 6.40 ( http://nmap.org ) at 2025-10-07 13:44 CST
Nmap scan report for bravexist.cn (104.21.67.121)
Host is up (0.092s latency).
Other addresses for bravexist.cn (not scanned): 172.67.221.229
Not shown: 994 filtered ports
PORT     STATE SERVICE
25/tcp   open  smtp
80/tcp   open  http
110/tcp  open  pop3
443/tcp  open  https
8080/tcp open  http-proxy
8443/tcp open  https-alt

Nmap done: 1 IP address (1 host up) scanned in 107.73 seconds
[root@centos7 ~]#

4.7 文件下载-wget-curl

4.7.1 wget

下载文件

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wget 选项 链接
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wget -O 自定义文件路径 链接
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# 下载并重命名为 install.sh
[root@centos7 ~]# wget -O install.sh https://get.docker.com/
--2025-10-07 13:32:55--  https://get.docker.com/
Resolving get.docker.com (get.docker.com)... 13.249.126.19, 13.249.126.85, 13.249.126.92, ...
Connecting to get.docker.com (get.docker.com)|13.249.126.19|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 21013 (21K) [text/plain]
Saving to: ‘install.sh’

100%[===================================================================================================================================================>] 21,013      --.-K/s   in 0.01s   

2025-10-07 13:32:56 (1.77 MB/s) - ‘install.sh’ saved [21013/21013]

[root@centos7 ~]# ls install.sh 
install.sh
[root@centos7 ~]#

4.7.2 curl

curl 也非常常用，请求网页内容，获取HTTP响应报文。windows 中也可使用。

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curl 链接
curl -v 链接
curl -I 链接
curl -vI 链接
curl -o 自定义文件路径 链接
  • -v 显示请求、响应详细信息
  • -I 之查看响应头，不看响应内容
  • -o 保存为文件
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# 请求简单的网页
[root@centos7 ~]# curl baidu.com
<html>
<meta http-equiv="refresh" content="0;url=http://www.baidu.com/">
</html>
[root@centos7 ~]# 

# 查看请求的详细信息
[root@centos7 ~]# curl -v baidu.com
* About to connect() to baidu.com port 80 (#0)
*   Trying 220.181.7.203...
* Connected to baidu.com (220.181.7.203) port 80 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: baidu.com
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Length: 81
< Content-Type: text/html
< Server: bfe
< Date: Tue, 07 Oct 2025 05:35:56 GMT
< 
<html>
<meta http-equiv="refresh" content="0;url=http://www.baidu.com/">
</html>
* Connection #0 to host baidu.com left intact
[root@centos7 ~]# 
[root@centos7 ~]# 

# 只看响应头
[root@centos7 ~]# curl -I baidu.com
HTTP/1.1 200 OK
Content-Length: 81
Content-Type: text/html
Server: bfe
Date: Tue, 07 Oct 2025 05:36:07 GMT

[root@centos7 ~]# 

# 查看详细请求信息和响应头
[root@centos7 ~]# curl -vI baidu.com
* About to connect() to baidu.com port 80 (#0)
*   Trying 39.156.70.37...
* Connected to baidu.com (39.156.70.37) port 80 (#0)
> HEAD / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: baidu.com
> Accept: */*
> 
< HTTP/1.1 200 OK
HTTP/1.1 200 OK
< Content-Length: 81
Content-Length: 81
< Content-Type: text/html
Content-Type: text/html
< Server: bfe
Server: bfe
< Date: Tue, 07 Oct 2025 05:36:54 GMT
Date: Tue, 07 Oct 2025 05:36:54 GMT

< 
* Connection #0 to host baidu.com left intact
[root@centos7 ~]# 

# 下载文件
[root@centos7 ~]# curl -o baidu.html baidu.com
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    81  100    81    0     0    287      0 --:--:-- --:--:-- --:--:--   288
[root@centos7 ~]# ls baidu.html -l
-rw-r--r-- 1 root root 81 Oct  7 13:37 baidu.html
[root@centos7 ~]#

五、封面图

封面图