DHCP 服务与管理

掌握要点

（1）了解 DHCP 服务的安装与配置。

（2）使用 DHCP 服务完成主机 IP 的自动获取。

部署流程

1.规划节点

IP	主机名	节点
11.0.1.128 192.168.2.2(LAN1)	xnode1	DHCP 服务器
11.0.1.129 （DHCP-LAN1）	client	DHCP 客户端

2.添加网卡（两个节点）

⚫打开虚拟机设置添加网卡，单击“添加”按钮，如图

⚫在弹出的对话框中，选择网络适配器，然后单击“完成”按钮

⚫选择网络适配器 2，设置模式为 LAN 区段，选择 LAN 区段 1，如图 3-15-3 所示。如果没有 LAN 区段 1，单击下方“LAN 区段（S）”按钮，然后在弹出的对话框中单击“添加” 按钮，最后单击“确定”按钮

⚫使用 ip a 命令可以查看到新添加的网卡，但并没有相关配置文件

3.修改网卡配置

⚫在DHCP服务端进入网卡配置文件目录，复制第一块网卡配置。

⚫修改网卡配置文件。

⚫启动网卡并查看。

[root@xnode1 ~]# cd /etc/sysconfig/network-scripts/ 
[root@xnode1 network-scripts]# cp -rvf ifcfg-eno16777736 ifcfg-eno33554984 
[root@xnode1 network-scripts]# vi ifcfg-eno33554984  
TYPE=Ethernet 
BOOTPROTO=static 
DEFROUTE=yes 
PEERDNS=yes 
PEERROUTES=yes 
IPV4_FAILURE_FATAL=no 
NAME=eno33554984 
DEVICE=eno33554984 
ONBOOT=yes 
IPADDR=192.168.2.2 
PREFIX=24 
GATEWAY=192.168.2.1 

[root@xnode1 ~]# ifup eno33554984
[root@xnode1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    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: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:8d:4e:69 brd ff:ff:ff:ff:ff:ff
    inet 11.0.1.128/24 brd 11.0.1.255 scope global dynamic eno16777736
       valid_lft 1579sec preferred_lft 1579sec
    inet6 fd15:4ba5:5a2b:1008:20c:29ff:fe8d:4e69/64 scope global noprefixroute dynamic 
       valid_lft 86395sec preferred_lft 14395sec
    inet6 fe80::20c:29ff:fe8d:4e69/64 scope link 
       valid_lft forever preferred_lft forever
3: eno33554984: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:8d:4e:73 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.2/24 brd 192.168.2.255 scope global eno33554984
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe8d:4e73/64 scope link 
       valid_lft forever preferred_lft forever

4.安装配置DHCP

⚫安装 DHCP 服务。

[root@xnode1 ~]# yum install -y  dhcp

5.DHCP的配置文件模板

⚫可以在以下的模板中找到DHCP的配置文件，只需要找到对应需要的去更改就可以了。

[root@xnode1 ~]#  cat /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example
#
# DHCP Server Configuration file.
#   see /usr/share/doc/dhcp*/dhcpd.conf.example
#   see dhcpd.conf(5) man page
#
# dhcpd.conf
#
# Sample configuration file for ISC dhcpd
#

# option definitions common to all supported networks...
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;         #默认租约时间单位秒
max-lease-time 7200;            #最大租约时间单位秒

# Use this to enble / disable dynamic dns updates globally.
#ddns-update-style none;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;

# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.

subnet 10.152.187.0 netmask 255.255.255.0 {       #定义子网
}

# This is a very basic subnet declaration.

subnet 10.254.239.0 netmask 255.255.255.224 {
  range 10.254.239.10 10.254.239.20;              #IP地址池
  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
}

# This declaration allows BOOTP clients to get dynamic addresses,
# which we don't really recommend.

subnet 10.254.239.32 netmask 255.255.255.224 {
  range dynamic-bootp 10.254.239.40 10.254.239.60;
  option broadcast-address 10.254.239.31;
  option routers rtr-239-32-1.example.org;
}

# A slightly different configuration for an internal subnet.
subnet 10.5.5.0 netmask 255.255.255.224 {
  range 10.5.5.26 10.5.5.30;
  option domain-name-servers ns1.internal.example.org;      #DNS服务器
  option domain-name "internal.example.org";                #可选 设置默认搜索域
  option routers 10.5.5.1;                                  #网关
  option broadcast-address 10.5.5.31;                       #可选 备选广播地址
  default-lease-time 600;
  max-lease-time 7200;
}

# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.

host passacaglia {                                
  hardware ethernet 0:0:c0:5d:bd:95;              
  filename "vmunix.passacaglia";
  server-name "toccata.fugue.com";
}

# Fixed IP addresses can also be specified for hosts.   These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP.   Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.
host fantasia {                                 #主机
  hardware ethernet 08:00:07:26:c0:a5;          #指定文件服务器MAC地址
  fixed-address fantasia.fugue.com;             #指定IP地址
}

# You can declare a class of clients and then do address allocation
# based on that.   The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.

class "foo" {
  match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
}

shared-network 224-29 {
  subnet 10.17.224.0 netmask 255.255.255.0 {
    option routers rtr-224.example.org;
  }
  subnet 10.0.29.0 netmask 255.255.255.0 {
    option routers rtr-29.example.org;
  }
  pool {
    allow members of "foo";
    range 10.17.224.10 10.17.224.250;
  }
  pool {
    deny members of "foo";
    range 10.0.29.10 10.0.29.230;
  }
}

⚫修改 DHCP 配置文件。

[root@xnode1 ~]# vim /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;
}

6.重启服务测试

⚫启动 DHCP 服务并设置开机自启，查看服务状态。

⚫Client 节点同样进行复制和修改网卡配置文件的操作。

[root@xnode1 ~]# systemctl start dhcpd 
[root@xnode1 ~]# systemctl enable dhcpd 
[root@xnode1 ~]# systemctl status dhcpd 

[root@client ~]# cd /etc/sysconfig/network-scripts/ 
[root@client network-scripts]# cp -rvf ifcfg-eno16777736 ifcfg-eno33554984 
[root@client network-scripts]# cat ifcfg-eno33554984  
TYPE=Ethernet 
BOOTPROTO=dhcp 
DEFROUTE=yes 
PEERDNS=yes 
PEERROUTES=yes 
IPV4_FAILURE_FATAL=no 
NAME=eno33554984 
DEVICE=eno33554984 
ONBOOT=yes 
[root@client ~]# systemctl restart network 
[root@client ~]# ip a
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: ens32: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:7c:32:c5 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.100/24 brd 192.168.2.255 scope global noprefixroute dynamic ens32
       valid_lft 599sec preferred_lft 599sec
    inet6 fe80::fade:7228:6397:cdb1/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever