Linux 网络基础

叁歲伎倆 2023-06-02 07:46 15阅读 0赞

![CentOS-Logo][]

本篇写一些关于`Linux`网络相关的基础命令、配置等。

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# hostname #

1.查看主机名

[root@localhost ~]# hostname
    localhost.localdomain

2.临时修改主机名

[root@localhost ~]# hostname server
    [root@localhost ~]# bash
    [root@server ~]# hostname
    server
    [root@server ~]# cat /etc/hostname
    localhost.localdomain
    [root@server ~]# hostnamectl status
       Static hostname: localhost.localdomain
    Transient hostname: server
             Icon name: computer-vm
               Chassis: vm
            Machine ID: ec132d04a74d4b7e828b3905a6b83437
               Boot ID: 8d0046a6366944b08b3eb7e69b431f6b
        Virtualization: vmware
      Operating System: CentOS Linux 7 (Core)
           CPE OS Name: cpe:/o:centos:centos:7
                Kernel: Linux 3.10.0-693.el7.x86_64
          Architecture: x86-64

3.永久修改主机名

[root@server ~]# hostnamectl set-hostname client
    [root@server ~]# bash
    [root@client ~]# hostname
    client
    [root@client ~]# cat /etc/hostname
    client
    [root@client ~]# hostnamectl status
       Static hostname: client
             Icon name: computer-vm
               Chassis: vm
            Machine ID: ec132d04a74d4b7e828b3905a6b83437
               Boot ID: 8d0046a6366944b08b3eb7e69b431f6b
        Virtualization: vmware
      Operating System: CentOS Linux 7 (Core)
           CPE OS Name: cpe:/o:centos:centos:7
                Kernel: Linux 3.10.0-693.el7.x86_64
          Architecture: x86-64

--------------------

# ifconfig #

1.查看已启用的网络接口信息

[root@localhost ~]# ifconfig
    ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.28.128  netmask 255.255.255.0  broadcast 192.168.28.255
            inet6 fe80::605e:3c48:bafd:e550  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
            RX packets 471  bytes 520023 (507.8 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 241  bytes 19798 (19.3 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 5916 (5.7 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 68  bytes 5916 (5.7 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
            inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
            ether 52:54:00:c3:55:5a  txqueuelen 1000  (Ethernet)
            RX packets 0  bytes 0 (0.0 B)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 0  bytes 0 (0.0 B)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

`ens33`：第一块以太网卡的名称。`ens33`中的`en`是`EtherNet`的缩写，表示网卡类型为以太网，`s`表示热插拔插槽上的设备`hot-plug Slot`，数字`33`表示插槽编号。

`lo`：回环网络接口，`lo`是`loopback`的缩写，它不代表真正的网络接口，而是一个虚拟的网络接口，其`IP`地址默认是`127.0.0.1`。回环地址通常仅用于对本机的网络测试。

`virbr0`：虚拟网桥的连接接口，默认为`0`号。其作用是连接主机上的虚机网卡提供外网的功能。

2.查看指定的网络接口信息

[root@localhost ~]# ifconfig ens33
    ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.28.129  netmask 255.255.255.0  broadcast 192.168.28.255
            inet6 fe80::eb90:4805:2c20:18ac  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:5b:e0:09  txqueuelen 1000  (Ethernet)
            RX packets 899  bytes 207777 (202.9 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 205  bytes 26253 (25.6 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

`inet`：表示网络接口的`IP`地址。

`netmask`：表示网络接口的子网掩码。

`broadcast`：表示网络接口所在网络的广播地址。

`ether`：表示网络接口的`MAC`地址。

3.设置网络接口的IP地址、子网掩码

*  ifconfig 接口名 IP地址 \[netmask 子网掩码\]
 *  ifconfig 接口名 IP地址\[/掩码长度\]

[root@localhost ~]# ifconfig ens33 192.168.100.10 netmask 255.255.255.0
    [root@localhost ~]# ifconfig ens33
    ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.100.10  netmask 255.255.255.0  broadcast 192.168.100.255
            inet6 fe80::605e:3c48:bafd:e550  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
            RX packets 626  bytes 562243 (549.0 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 262  bytes 23344 (22.7 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

> 临时配置，重启失效。不指定子网掩码时，将使用`IP`地址所在分类的默认子网掩码。

4.临时禁用或者重新激活网卡

*  ifconfig 接口名 down

[root@localhost ~]# ifconfig ens33 down
    [root@localhost ~]# ifconfig ens33
    ens33: flags=4098<BROADCAST,MULTICAST>  mtu 1500
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
            RX packets 1067  bytes 667057 (651.4 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 263  bytes 23404 (22.8 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

*  ifconfig 接口名 up

[root@localhost ~]# ifconfig ens33 up
    [root@localhost ~]# ifconfig ens33
    ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.28.128  netmask 255.255.255.0  broadcast 192.168.28.255
            inet6 fe80::605e:3c48:bafd:e550  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
            RX packets 1078  bytes 668954 (653.2 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 285  bytes 26835 (26.2 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

5.设置虚拟网络接口

*  ifconfig 接口名:序号 IP地址

[root@localhost ~]# ifconfig ens33:0 192.168.100.10
    [root@localhost ~]# ifconfig ens33:0
    ens33:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.100.10  netmask 255.255.255.0  broadcast 192.168.100.255
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
    [root@localhost ~]# ifconfig ens33:0 down

--------------------

# route #

1.查看当前主机中的路由表信息

`-n`：将路由记录中的地址显示位数字形式

[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 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

[root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.28.2    0.0.0.0         UG    100    0        0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

2.添加、删除到指定网段的路由记录

*  route add -net 网段地址 gw IP地址

[root@localhost ~]# route add -net 192.168.100.0/24 gw 192.168.28.1
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.28.2    0.0.0.0         UG    100    0        0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.100.0   192.168.28.1    255.255.255.0   UG    0      0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

*  route del -net 网段地址

[root@localhost ~]# route del -net 192.168.100.0/24
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.28.2    0.0.0.0         UG    100    0        0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

3。添加、删除默认网关记录

*  route add default gw IP地址

[root@localhost ~]# route add default gw 192.168.28.1
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.28.1    0.0.0.0         UG    0      0        0 ens33
    0.0.0.0         192.168.28.2    0.0.0.0         UG    100    0        0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

*  route del default gw IP地址

[root@localhost ~]# route del default gw 192.168.28.1
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.28.2    0.0.0.0         UG    100    0        0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U     100    0        0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

--------------------

# netstat #

*  查看当前的网络连接状态、路由表、接口统计等信息。

`-n`：以数字的形式显示相关的主机地址、端口等信息。  
`-t`：查看`TCP`传输控制协议相关的信息。  
`-u`：显示`UDP`用户数据报协议相关的信息。  
`-a`：显示当前主机中所有活动的网络连接信息，包括监听、非监听状态的服务端口。  
`-l`：显示处于监听`Listening`状态的网络连接及端口信息。  
`-p`：显示与网络连接相关联的进程号、进程名称信息，该选项需要`root`权限。  
`-r`：显示路由表信息。

[root@localhost ~]# netstat -ntap
    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      1/systemd           
    tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN      1335/dnsmasq        
    tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1009/sshd           
    tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      1012/cupsd          
    tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1306/master         
    tcp6       0      0 :::111                  :::*                    LISTEN      1/systemd           
    tcp6       0      0 :::22                   :::*                    LISTEN      1009/sshd           
    tcp6       0      0 ::1:631                 :::*                    LISTEN      1012/cupsd          
    tcp6       0      0 ::1:25                  :::*                    LISTEN      1306/master

[root@localhost ~]# netstat -nuap
    Active Internet connections (servers and established)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
    udp        0      0 0.0.0.0:5353            0.0.0.0:*                           578/avahi-daemon: r 
    udp        0      0 0.0.0.0:12162           0.0.0.0:*                           799/dhclient        
    udp        0      0 192.168.122.1:53        0.0.0.0:*                           1335/dnsmasq        
    udp        0      0 0.0.0.0:67              0.0.0.0:*                           1335/dnsmasq        
    udp        0      0 0.0.0.0:68              0.0.0.0:*                           799/dhclient        
    udp        0      0 127.0.0.1:323           0.0.0.0:*                           624/chronyd         
    udp        0      0 0.0.0.0:51570           0.0.0.0:*                           578/avahi-daemon: r 
    udp6       0      0 :::25751                :::*                                799/dhclient        
    udp6       0      0 ::1:323                 :::*                                624/chronyd

[root@localhost ~]# netstat -r
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
    default         promote.cache-d 0.0.0.0         UG        0 0          0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U         0 0          0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0
    [root@localhost ~]# netstat -rn
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
    0.0.0.0         192.168.28.2    0.0.0.0         UG        0 0          0 ens33
    192.168.28.0    0.0.0.0         255.255.255.0   U         0 0          0 ens33
    192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0

--------------------

# ping #

*  测试网络连通性

[root@localhost ~]# ping -c 4 127.0.0.1
    PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
    64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.036 ms
    64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.084 ms
    64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.085 ms
    64 bytes from 127.0.0.1: icmp_seq=4 ttl=64 time=0.096 ms
    
    --- 127.0.0.1 ping statistics ---
    4 packets transmitted, 4 received, 0% packet loss, time 3009ms
    rtt min/avg/max/mdev = 0.036/0.075/0.096/0.023 ms

--------------------

# traceroute #

*  跟踪数据包的路由途径

[root@localhost ~]# traceroute 127.0.0.1
    traceroute to 127.0.0.1 (127.0.0.1), 30 hops max, 60 byte packets
     1  localhost (127.0.0.1)  0.040 ms  0.010 ms  0.008 ms

`traceroute`命令能够比`ping`命令更加准确地定位网络连接的故障点，因此执行速度会比`ping`命令稍慢。在网络测试与排错过程中，通常会先使用`ping`命令测试与目的主机的网络连接，如果发现网络连接有故障，再使用`traceroute`命令跟踪查看是在哪个中间结点存在故障。

--------------------

# nslookup #

*  测试 DNS 域名解析

[root@localhost ~]# nslookup www.baidu.com
    Server:     192.168.28.2
    Address:    192.168.28.2#53
    
    Non-authoritative answer:
    www.baidu.com   canonical name = www.a.shifen.com.
    Name:   www.a.shifen.com
    Address: 183.232.231.174
    Name:   www.a.shifen.com
    Address: 183.232.231.172

--------------------

# ifcfg-\* #

*  修改网络接口配置文件

[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33
    TYPE=Ethernet
    BOOTPROTO=static
    DEVICE=ens33
    ONBOOT=yes
    IPADDR=192.168.100.10
    NETMASK=255.255.255.0
    GATEWAY=192.168.100.1

`TYPE`：设置网卡类型，`Ethernet`表示以太网。  
`BOOTPROTO`：设置网络接口的配置方式，值为`static`时表示使用静态指定的`IP`地址，为`dhcp`时表示通过`DHCP`的方式动态获取地址。  
`DEVICE`：设置网络接口的名称。  
`ONBOOT`：设置网络接口是否在`Linux`操作系统启动时激活。  
`IPADDR`：设置网络接口的`IP`地址。  
`NETMASK`：设置网络接口的子网掩码。  
`GATEWAY`：设置网络接口的默认网关地址。

*  启用、禁用单个网络接口配置

[root@localhost ~]# ifdown ens33
    Device 'ens33' successfully disconnected.
    [root@localhost ~]# ifup ens33
    Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/5)
    [root@localhost ~]# ifconfig ens33
    ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.100.10  netmask 255.255.255.0  broadcast 192.168.100.255
            inet6 fe80::20c:29ff:febc:ab96  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:bc:ab:96  txqueuelen 1000  (Ethernet)
            RX packets 5640  bytes 1889047 (1.8 MiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 410  bytes 37045 (36.1 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

*  重启网络服务（会先关闭所有的网络接口，再根据配置文件重新启用所有的网络接口）

[root@localhost ~]# service network restart
    Restarting network (via systemctl):                        [  OK  ]

[root@localhost ~]# systemctl restart network

--------------------

# /etc/hosts #

*  本地主机映射文件

[root@localhost ~]# cat /etc/hosts
    127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
    ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

> 当访问一个未知的域名时，先查找该文件中是否有相应的映射记录，如果找不到再去向`DNS`服务器查询。

--------------------

# /etc/resolv.conf #

*  指定为本机提供DNS解析的服务器地址，最多可以指定`3`个，第`3`个后面的会被忽略。

[root@localhost ~]# cat /etc/resolv.conf
    # Generated by NetworkManager
    search localdomain
    nameserver 192.168.28.2

`search localdomain`：设置默认的搜索域（域名扩展名）。

例如，当访问主机`localhost`时，就相当于访问`localhost.localdomain`。

--------------------

# scp #

*  远程复制

本地 → 对方

[root@localhost ~]# scp /etc/hosts root@192.168.28.129:/etc/hosts
    The authenticity of host '192.168.28.129 (192.168.28.129)' can't be established.
    ECDSA key fingerprint is SHA256:QmZtJT0piBUSkF9P3GfYf3uEogzBWs08sI7j0eBE/cI.
    ECDSA key fingerprint is MD5:ef:e6:06:22:8a:0f:24:00:f8:af:a5:59:5b:a2:b8:b1.
    Are you sure you want to continue connecting (yes/no)? yes
    Warning: Permanently added '192.168.28.129' (ECDSA) to the list of known hosts.
    root@192.168.28.129's password: 
    hosts                                         100%  158   172.5KB/s   00:00

对方 → 本地

[root@localhost ~]# scp root@192.168.28.129:/etc/hosts /etc/hosts
    root@192.168.28.129's password: 
    hosts                                         100%  158    90.5KB/s   00:00

转载于:https://www.cnblogs.com/llife/p/11495317.html

[CentOS-Logo]: /images/20230601/51cf8c9b82b8400795bde6d82378615b.png