centos 配置IP、路由网关和DNS

拼搏现实的明天。 2022-04-18 02:06 497阅读 0赞

# 1 配置IP #

centos 配置ip有两种方法，一种是通过ifconfig命令进行临时配置，一种是通过ifcfg配置文件进行永久配置。

## 1.1 ifconfig 配置ip(重启失效) ##

ifconfig eth1 192.168.12.18 netmask 255.255.255.0

该种方式可以使改变即时生效，重启后会恢复为原来的IP。

[root@localhost ~]# ifconfig eth1
    eth1: flags=4098<BROADCAST,MULTICAST>  mtu 1500
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 425  bytes 31142 (30.4 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 143  bytes 14828 (14.4 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    [root@localhost ~]# 
    [root@localhost ~]# ifconfig eth1 192.168.12.18 netmask 255.255.255.0
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifconfig eth1
    eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.12.18  netmask 255.255.255.0  broadcast 192.168.12.255
            inet6 fe80::20c:29ff:fe9b:52dd  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 428  bytes 31322 (30.5 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 148  bytes 15266 (14.9 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    [root@localhost ~]#

## 1.2 ifcfg配置文件配置ip(永久有效) ##

### 1.2.1 静态地址 ###

(1) 查看配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
    TYPE=Ethernet
    DEFROUTE=yes
    PROXY_METHOD=none
    BROWSER_ONLY=no
    BOOTPROTO=static
    IPV4_FAILURE_FATAL=no
    IPV6INIT=yes
    IPV6_AUTOCONF=yes
    IPV6_DEFROUTE=yes
    IPV6_FAILURE_FATAL=no
    IPV6_ADDR_GEN_MODE=stable-privacy
    NAME=eth1
    UUID=0de93453-8fa0-4080-9a53-5fadae0a8af4
    DEVICE=eth1
    HWADDR=00:0c:29:9b:52:dd
    IPADDR=192.168.12.135
    NETMASK=255.255.255.0
    GATEWAY=192.168.12.1
    DNS1=192.168.12.1
    BROADCAST=192.168.1.255
    ONBOOT=yes

(2) 启动

[root@localhost ~]# ifconfig eth1
    eth1: flags=4098<BROADCAST,MULTICAST>  mtu 1500
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 718  bytes 50063 (48.8 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 176  bytes 18390 (17.9 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    [root@localhost ~]# 
    [root@localhost ~]# ifup eth1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifconfig eth1
    eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.12.135  netmask 255.255.255.0  broadcast 192.168.1.255
            inet6 fe80::20c:29ff:fe9b:52dd  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 722  bytes 50303 (49.1 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 187  bytes 19188 (18.7 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

### 1.2.2 动态地址 ###

(1) 查看配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 
    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
    NAME=eth1
    UUID=0de93453-8fa0-4080-9a53-5fadae0a8af4
    DEVICE=eth1
    HWADDR=00:0c:29:9b:52:dd
    ONBOOT=yes

(2) 启动

[root@localhost ~]# ifconfig eth1
    eth1: flags=4098<BROADCAST,MULTICAST>  mtu 1500
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 570  bytes 40025 (39.0 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 148  bytes 15266 (14.9 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    [root@localhost ~]# 
    [root@localhost ~]# ifup eth1
    
    Determining IP information for eth1... done.
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifconfig eth1
    eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.233.137  netmask 255.255.255.0  broadcast 192.168.233.255
            inet6 fe80::20c:29ff:fe9b:52dd  prefixlen 64  scopeid 0x20<link>
            ether 00:0c:29:9b:52:dd  txqueuelen 1000  (Ethernet)
            RX packets 577  bytes 41039 (40.0 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 159  bytes 16656 (16.2 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# 2 配置路由网关 #

centos 配置ip有两种方法，一种是通过route命令进行临时配置，一种是通过配置文件进行永久配置。

## 2.1 route 配置默认网关(重启失效) ##

添加默认路由

route add default gw 192.168.1.1 dev eth0

[root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.12.1    0.0.0.0         UG    0      0        0 eth1
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     1003   0        0 eth1
    192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# route add default gw 192.168.1.1 dev eth0
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
    0.0.0.0         192.168.12.1    0.0.0.0         UG    0      0        0 eth1
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     1003   0        0 eth1
    192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
    [root@localhost ~]#

## 2.2 配置文件配置网关 ##

(1) 永久保存路由

(a) 在/etc/rc.local 里添加： route add default gw 192.168.1.1 dev eth0

(b) 在/etc/sysconfig/network 里添加到末尾： GATEWAY=192.168.1.1

(d) 在/etc/sysconfig/static-router添加：any net 192.168.1.0/24 gw 192.168.1.1

### 2.2.1 ifcfg配置文件 ###

适合各种连接方式，推荐使用这种方式添加默认路由。在对于网口配置文件添加 GATEWAY=192.168.1.1

(1) 查看配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
    TYPE=Ethernet
    DEFROUTE=yes    // 默认路由
    PROXY_METHOD=none
    BROWSER_ONLY=no
    BOOTPROTO=static
    IPV4_FAILURE_FATAL=no
    IPV6INIT=yes
    IPV6_AUTOCONF=yes
    IPV6_DEFROUTE=yes
    IPV6_FAILURE_FATAL=no
    IPV6_ADDR_GEN_MODE=stable-privacy
    NAME=eth0
    UUID=0de93453-8fa0-4080-9a53-5fadae0a8af3
    DEVICE=eth0
    HWADDR=00:0c:29:9b:52:d3
    IPADDR=192.168.1.135
    NETMASK=255.255.255.0
    GATEWAY=192.168.1.1    // 网关
    DNS1=192.168.1.1
    BROADCAST=192.168.1.255
    ONBOOT=yes

(2) 启动

[root@localhost ~]# route del default gw 192.168.1.1 dev eth0
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.12.1    0.0.0.0         UG    0      0        0 eth1
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     1003   0        0 eth1
    192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
    [root@localhost ~]# ifdown eth0
    [root@localhost ~]# ifup eth0
    [root@localhost ~]# route -n
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     1003   0        0 eth1
    192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1

# 3 配置DNS #

## 3.1 概述 ##

(1) 当电脑要访问一个域名时，要将域名翻译成IP地址。

(a) 这个过程通常会先访问/etc/hosts，看本地是否有对应的hostname IP记录。

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

(b) 如果没有就去查询DNS服务器，通过/etc/resolv.conf 得到dns服务器地址。

[root@localhost ~]# cat /etc/resolv.conf 
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.1.1

(2) 当在eth接口启用DHCP后，本地resolv.conf文件将被修改，resolv.conf文件中的DNS地址将被改为从DHCP获取到的地址。这种从DHCP获得的DNS即是Peer DNS。

(3) 启用DHCP后即便修改/etc/resolv.conf，不久又恢复成原样。

此时，你得要在 /etc/sysconfig/network-scripts/ifcfg-eth0 等相关档案内，增加一行：PEERDNS=no，然后重新启动网络即可。

## 3.2 resolv.conf 配置DNS ##

(1) 直接在配置文件增加dns即可，但是如果网口配置了下述情况

(a) ifcfg 静态地址配置了 DNS1，DNS2，则重启网卡会重新把DNS写入文件。

(b) ifcfg 动态获取地址，且没有配置PEERDNS=no，则重启网卡会重新把动态获取的DNS写入文件。

(2) 查看配置

cat /etc/resolv.conf

[root@localhost ~]# cat /etc/resolv.conf
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.12.1

## 3.3 ifcfg 配置DNS ##

### 3.3.1 静态地址 ###

(1) 查看配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1
    TYPE=Ethernet
    DEFROUTE=yes
    PROXY_METHOD=none
    BROWSER_ONLY=no
    BOOTPROTO=static      // 静态方式
    IPV4_FAILURE_FATAL=no
    IPV6INIT=yes
    IPV6_AUTOCONF=yes
    IPV6_DEFROUTE=yes
    IPV6_FAILURE_FATAL=no
    IPV6_ADDR_GEN_MODE=stable-privacy
    NAME=eth1
    UUID=0de93453-8fa0-4080-9a53-5fadae0a8af4
    DEVICE=eth1
    HWADDR=00:0c:29:9b:52:dd
    IPADDR=192.168.12.135
    NETMASK=255.255.255.0
    GATEWAY=192.168.12.1
    DNS1=192.168.12.1         // DNS 服务器地址
    BROADCAST=192.168.1.255
    ONBOOT=yes

(2) 启动

[root@localhost ~]# cat /etc/resolv.conf
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.1.1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifup eth1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# cat /etc/resolv.conf
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.12.1
    [root@localhost ~]#

### 3.3.2 动态地址 ###

默认为 PEERDNS=yes

(1) 查看配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 
    TYPE=Ethernet
    PROXY_METHOD=none
    BROWSER_ONLY=no
    BOOTPROTO=dhcp   // 动态获取地址
    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=eth1
    UUID=0de93453-8fa0-4080-9a53-5fadae0a8af4
    DEVICE=eth1
    HWADDR=00:0c:29:9b:52:dd
    ONBOOT=yes

(2) 启动

root@localhost ~]# cat /etc/resolv.conf 
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.1.1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifdown eth1
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# ifup eth1
    
    Determining IP information for eth1... done.
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# 
    [root@localhost ~]# cat /etc/resolv.conf 
    ; generated by /usr/sbin/dhclient-script
    search localdomain
    nameserver 192.168.233.2
    [root@localhost ~]#