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CentOS7搭建DHCP服务器详解程序员

• 智能运维

(1).实验环境

　　DHCP服务器：youxi1　　192.168.1.6（外网）

　　测试主机：youxi2　　192.168.1.7（外网）

　　DHCP是C/S模式，服务器端监听端口67/UDP（bootps），客户端默监听认端口68/UDP（bootpc）

(2).实验

1）在DHCP服务器上安装dhcp服务

[[email protected] ~]# yum -y install dhcp

2）在DHCP服务器添加一块网卡

CentOS7搭建DHCP服务器详解程序员

　　使用命令ip a sh可以看到新加的网卡，但并没有相关配置文件

[[email protected] ~]# ip a sh 
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:29:72:1e:89 brd ff:ff:ff:ff:ff:ff 
    inet 192.168.1.6/24 brd 192.168.1.255 scope global ens33 
       valid_lft forever preferred_lft forever 
    inet6 fe80::20c:29ff:fe72:1e89/64 scope link  
       valid_lft forever preferred_lft forever 
3: ens38: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 
    link/ether 00:0c:29:72:1e:93 brd ff:ff:ff:ff:ff:ff 
[[email protected] ~]# ls /etc/sysconfig/network-scripts/ 
ifcfg-ens33  ifdown-ipv6    ifdown-Team      ifup-eth    ifup-post      ifup-tunnel 
ifcfg-lo     ifdown-isdn    ifdown-TeamPort  ifup-ippp   ifup-ppp       ifup-wireless 
ifdown       ifdown-post    ifdown-tunnel    ifup-ipv6   ifup-routes    init.ipv6-global 
ifdown-bnep  ifdown-ppp     ifup             ifup-isdn   ifup-sit       network-functions 
ifdown-eth   ifdown-routes  ifup-aliases     ifup-plip   ifup-Team      network-functions-ipv6 
ifdown-ippp  ifdown-sit     ifup-bnep        ifup-plusb  ifup-TeamPort

　　这是直接拷贝ifcfg-ens33并重命名为ifcfg-ens38，并删除不要的配置信息，修改部分配置

[[email protected] ~]# cd /etc/sysconfig/network-scripts/ 
[[email protected] network-scripts]# cp ifcfg-ens33 ifcfg-ens38 
[[email protected] network-scripts]# cat ifcfg-ens38 
TYPE="Ethernet" 
PROXY_METHOD="none" 
BROWSER_ONLY="no" 
BOOTPROTO="static" 
DEFROUTE="yes" 
IPV4_FAILURE_FATAL="yes" 
IPADDR="192.168.2.6" 
NETMASK="255.255.255.0" 
GATEWAY="192.168.2.1" 
DNS1="192.168.2.1" 
NAME="ens38" 
DEVICE="ens38" 
ONBOOT="yes" 
[[email protected] network-scripts]# ifup ens38　　//启用ens38网卡 
[[email protected] network-scripts]# ip a sh dev ens38 
3: ens38: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 
link/ether 00:0c:29:72:1e:93 brd ff:ff:ff:ff:ff:ff 
inet 192.168.2.6/24 brd 192.168.2.255 scope global ens38 
valid_lft forever preferred_lft forever 
inet6 fe80::20c:29ff:fe72:1e93/64 scope link  
valid_lft forever preferred_lft forever　

3）常用配置文件参数说明

　　subnet [网络号] netmask [子网掩码] {…}

　　作用：定义作用域，指定子网掩码

　　range [起始IP地址] [结束IP地址]

　　作用：指定动态获取IP地址范围，可以声明多个range但范围不能重合。

　　option routers [IP地址]

　　作用：为客户端指定默认网关，可以全局可以局部

　　option domain-name [域名]

　　作用：为客户端指定默认的域，可以全局可以局部

　　option domain-name-servers [IP地址]

　　作用：为客户端指定默认DNS服务器地址，可以全局可以局部

　　default-lease-time [数字]

　　作用：默认最小租约期限（单位秒），可以全局可以局部

　　max-lease-time [数字]

　　作用：最长租约期限（单位秒），可以全局可以局部

　　host [主机注释名]{

　　　　hardware [硬件类型] [硬件地址]

　　　　fixed-address [IP地址]

　　}

　　作用：用于绑定IP地址，一般硬件类型是以太网（ethernet），硬件地址是MAC地址

　　log-facility [日志属性]

　　作用：定义自身的日志属性（在/etc/rsyslog.conf日志服务配置文件中定义相应的属性会将日志存放到何处）

4）编辑DHCP配置文件

　　dhcp配置文件地址是/etc/dhcp/dhcpd.conf

[[email protected] ~]# cat /etc/dhcp/dhcpd.conf  
# 
# DHCP Server Configuration file. 
#   see /usr/share/doc/dhcp*/dhcpd.conf.example 
#   see dhcpd.conf(5) man page 
# 
subnet 192.168.2.0 netmask 255.255.255.0 { 
        range 192.168.2.100 192.168.2.254; 
        option domain-name-servers 192.168.2.1; 
        option domain-name "test.cn"; 
        option routers 192.168.2.1; 
        option broadcast-address 192.168.2.255; 
        default-lease-time 600; 
        max-lease-time 7200; 
}

　　启动dhcpd，并开机自启

[[email protected] network-scripts]# systemctl start dhcpd 
[[email protected] network-scripts]# systemctl enable dhcpd 
[[email protected] network-scripts]# systemctl status dhcpd 
● dhcpd.service - DHCPv4 Server Daemon 
   Loaded: loaded (/usr/lib/systemd/system/dhcpd.service; enabled; vendor preset: enabled) 
   Active: active (running) since 四 2019-05-16 23:06:15 CST; 11s ago 
     Docs: man:dhcpd(8) 
           man:dhcpd.conf(5) 
 Main PID: 8364 (dhcpd) 
   Status: "Dispatching packets..." 
   CGroup: /system.slice/dhcpd.service 
           └─8364 /usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid 
 
5月 16 23:06:15 youxi1 dhcpd[8364]: Sending on   LPF/ens38/00:0c:29:72:1e:93/192.168.2.0/24 
5月 16 23:06:15 youxi1 dhcpd[8364]: ved. 
5月 16 23:06:15 youxi1 dhcpd[8364]: No subnet declaration for ens33 (192.168.1.6). 
5月 16 23:06:15 youxi1 dhcpd[8364]: ** Ignoring requests on ens33.  If this is not what 
5月 16 23:06:15 youxi1 dhcpd[8364]:    you want, please write a subnet declaration 
5月 16 23:06:15 youxi1 dhcpd[8364]:    in your dhcpd.conf file for the network segment 
5月 16 23:06:15 youxi1 dhcpd[8364]:    to which interface ens33 is attached. ** 
5月 16 23:06:15 youxi1 dhcpd[8364]: nt 
5月 16 23:06:15 youxi1 dhcpd[8364]: Sending on   Socket/fallback/fallback-net 
5月 16 23:06:15 youxi1 systemd[1]: Started DHCPv4 Server Daemon.

5）添加测试主机网卡，一样LAN1

　　编辑ens38网卡配置文件，并启动

[[email protected] ~]# cd /etc/sysconfig/network-scripts/ 
[[email protected] network-scripts]# cp ifcfg-ens33 ifcfg-ens38 
[[email protected] network-scripts]# cat ifcfg-ens38 
TYPE="Ethernet" 
PROXY_METHOD="none" 
BROWSER_ONLY="no" 
BOOTPROTO="dhcp" 
DEFROUTE="yes" 
IPV4_FAILURE_FATAL="yes" 
NAME="ens38" 
DEVICE="ens38" 
ONBOOT="yes" 
[[email protected] network-scripts]# ifup ens38 
正在确定 ens38 的 IP 信息... 完成。 
[[email protected] network-scripts]# ip a sh dev ens38 
3: ens38: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 
link/ether 00:0c:29:f2:7e:5c brd ff:ff:ff:ff:ff:ff 
inet 192.168.2.100/24 brd 192.168.2.255 scope global dynamic ens38 
valid_lft 589sec preferred_lft 589sec 
inet6 fe80::20c:29ff:fef2:7e5c/64 scope link  
valid_lft forever preferred_lft forever

6)如果想要IP绑定MAC

　　修改DHCP服务器上的配置文件，重启dhcp服务

[[email protected] ~]# cat /etc/dhcp/dhcpd.conf  
# 
# DHCP Server Configuration file. 
#   see /usr/share/doc/dhcp*/dhcpd.conf.example 
#   see dhcpd.conf(5) man page 
# 
subnet 192.168.2.0 netmask 255.255.255.0 { 
        range 192.168.2.100 192.168.2.254; 
        option domain-name-servers 192.168.2.1; 
        option domain-name "test.cn"; 
        option routers 192.168.2.1; 
        option broadcast-address 192.168.2.255; 
        default-lease-time 600; 
        max-lease-time 7200; 
        host youxi2{ 
                hardware ethernet 00:0c:29:f2:7e:5c; 
                fixed-address 192.168.2.200; 
        } 
}
[[email protected] ~]# systemctl restart dhcpd

　　重启测试主机上的network服务

[[email protected] ~]# ip a sh dev ens38 
3: ens38: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 
    link/ether 00:0c:29:f2:7e:5c brd ff:ff:ff:ff:ff:ff 
    inet 192.168.2.100/24 brd 192.168.2.255 scope global dynamic ens38 
       valid_lft 355sec preferred_lft 355sec 
    inet6 fe80::20c:29ff:fef2:7e5c/64 scope link  
       valid_lft forever preferred_lft forever 
[[email protected] ~]# systemctl restart network 
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details. 
[[email protected] ~]# ip a sh dev ens38         
3: ens38: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 
    link/ether 00:0c:29:f2:7e:5c brd ff:ff:ff:ff:ff:ff 
    inet 192.168.2.200/24 brd 192.168.2.255 scope global dynamic ens38 
       valid_lft 546sec preferred_lft 546sec 
    inet6 fe80::20c:29ff:fef2:7e5c/64 scope link  
       valid_lft forever preferred_lft forever

7）常看相关文件

　　DHCP服务器上的租约数据库文件

[[email protected] ~]# cat /var/lib/dhcpd/dhcpd.leases 
# The format of this file is documented in the dhcpd.leases(5) manual page. 
# This lease file was written by isc-dhcp-4.2.5 
 
lease 192.168.2.100 { 
  starts 6 2019/05/18 06:56:08; 
  ends 6 2019/05/18 07:06:08; 
  tstp 6 2019/05/18 07:06:08; 
  cltt 6 2019/05/18 06:56:08; 
  binding state active; 
  next binding state free; 
  rewind binding state free; 
  hardware ethernet 00:0c:29:f2:7e:5c; 
  client-hostname "youxi2"; 
} 
server-duid "/000/001/000/001$p8/347/000/014)r/036/223";

　　在测试主机上查看DNS

[[email protected] ~]# cat /etc/resolv.conf 
; generated by /usr/sbin/dhclient-script 
search test.cn 
nameserver 192.168.1.1

　　查看网关

[[email protected] ~]# 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 ens33 
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 ens33 
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 ens33 
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 ens38

　　

原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/2780.html

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