DHCP服务器的搭建（RHEL8 ）
本次实验用到两台虚拟机演示dhcp服务器的搭建并测试
| 虚拟机 | 作用 |
|---|---|
| rhel8 | dhcp服务器 |
| rhel7 | 测试机 |
一.DHCP服务器
1.什么是dhcp服务器
DHCP（Dynamic Host Configuration Protocol ,动态主机配置协议）通常被用在大型的局域网络中，主要作用是集中的管理，分配IP地址，使网络环境中的主机动态的获得IP地址，Gateway地址，DNS服务器地址等信息，并能够提升地址的使用率。
2.端口
DHCP服务端口是UDP67和UDP68,这两个端口是正常的DHCP服务端口,可以理解为一个发送,一个接收。
1、客户端向68端口(bootps)广播请求配置,
2、服务器向67端口(bootpc)广播回应请求
二.dhcp服务器的搭建
在rhel8中：
1.配置静态网络
vim /etc/sysconfig/network-scripts/ifcfg-ens160
DEVICE=ens160
ONBOOT=yes
BOOTPROTO=none
IPADDR=172.25.254.30
NETMASK=255.255.255.0
[root@RHEL8 ~]# systemctl restart NetworkManager
[root@RHEL8 ~]# ifconfig
ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.25.254.30 netmask 255.255.255.0 broadcast 172.25.254.255
inet6 fe80::20c:29ff:fe94:a86 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:94:0a:86 txqueuelen 1000 (Ethernet)
RX packets 3724 bytes 272842 (266.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 139 bytes 14574 (14.2 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 1000 (Local Loopback)
RX packets 48 bytes 4944 (4.8 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 48 bytes 4944 (4.8 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2.把镜像接入光驱，作用是找到dhcpd安装包
3.df查看光驱挂载位置
[root@RHEL8 ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 910516 0 910516 0% /dev
tmpfs 924700 0 924700 0% /dev/shm
tmpfs 924700 9848 914852 2% /run
tmpfs 924700 0 924700 0% /sys/fs/cgroup
/dev/nvme0n1p3 8181760 4098312 4083448 51% /
/dev/nvme0n1p1 199328 141344 57984 71% /boot
tmpfs 184940 16 184924 1% /run/user/42
tmpfs 184940 3488 181452 2% /run/user/0
/dev/sr0 6935944 6935944 0 100% /run/media/root/RHEL-8-0-0-BaseOS-x86_64 ##光驱挂载点
4.查找dhcp安装包
[root@RHEL8 ~]# cd /run/media/root/RHEL-8-0-0-BaseOS-x86_64/BaseOS/Packages/
[root@RHEL8 Packages]# ls dhcp-*
dhcp-client-4.3.6-30.el8.x86_64.rpm dhcp-libs-4.3.6-30.el8.x86_64.rpm
dhcp-common-4.3.6-30.el8.noarch.rpm dhcp-relay-4.3.6-30.el8.x86_64.rpm
dhcp-libs-4.3.6-30.el8.i686.rpm dhcp-server-4.3.6-30.el8.x86_64.rpm
5.安装dhcp
[root@RHEL8 Packages]# rpm -ivh dhcp-server-4.3.6-30.el8.x86_64.rpm
warning: dhcp-server-4.3.6-30.el8.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Verifying... ################################# [100%]
Preparing... ################################# [100%]
Updating / installing...
1:dhcp-server-12:4.3.6-30.el8 ################################# [100%]
6.配置dhcp文件
[root@RHEL8 Packages]# cd /etc/dhcp/
[root@RHEL8 dhcp]# ls
dhclient.conf dhclient.d dhcpd6.conf dhcpd.conf
[root@RHEL8 dhcp]# cp /usr/share/doc/dhcp-server/dhcpd.conf.example dhcpd.conf
[root@RHEL8 dhcp]# vim dhcpd.conf
1 # dhcpd.conf
2 #
3 # Sample configuration file for ISC dhcpd
4 #
5
6 # option definitions common to all supported networks...
7 option domain-name "example.org";
8 option domain-name-servers 114.114.114.114;
9
10 default-lease-time 600;
11 max-lease-time 7200;
12
13 # Use this to enble / disable dynamic dns updates globally.
14 #ddns-update-style none;
15
16 # If this DHCP server is the official DHCP server for the local
17 # network, the authoritative directive should be uncommented.
18 #authoritative;
19
20 # Use this to send dhcp log messages to a different log file (you also
21 # have to hack syslog.conf to complete the redirection).
22 log-facility local7;
23
24 # No service will be given on this subnet, but declaring it helps the
25 # DHCP server to understand the network topology.
26
27
28 # This is a very basic subnet declaration.
29
30 subnet 172.25.254.0 netmask 255.255.255.0 { ##设定网段
31 range 172.25.254.88 172.25.254.100; ##分配ip地址
32 option routers 172.25.254.30; ##网关
33 }
7.重启服务
[root@RHEL8 dhcp]# systemctl restart dhcpd
三.测试dhcp服务器
在rhel7：
1.配置网络
[root@rhel7 ~]# vim /etc/sysconfig/network-scripts/ifcfg-westos
DEVICE=ens33
ONBOOT=yes
BOOTPROTO=dhcp
NAME=westos
2.rhel7中配置dhcp网络看是否可以获得ip，并查看网卡的物理硬件地址
在rhel8中查看ip分配情况
“注意在rhel7中dhcp的安装如下：”
cd "/run/media/root/RHEL-7.6 Server.x86_64/Packages"
rpm -ivh dhcp-4.2.5-68.el7_5.1.x86_64.rpm