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使用Dnsmasq部署DHCP服务

2018-07-14 15:30:15作者:LINUX人稿源:运维之美

DNSmasq是一个小巧且方便地用于配置DNS和DHCP的工具,适用于小型网络。本文将使用Dnsmasq部署DHCP服务。DNSmasq提供了DNS功能和可选择的DHCP功能可以取代dhcpd(DHCPD服务配置)和Bind等服务。DNSmasq配置起来更简单,更适用于虚拟化和大数据环境的部署。

DNSmasq所提供的DHCP服务也是和dhcpd十分相近的。如同共动态地址分配,可以通过MAC地址预先指定静态的IP地址给特定的主机等等。

 

使用DNSmasq提供DHCP服务也是相当简单的事情。配置文件/etc/dnsmasq.conf中的注释已经给出了非常详细的解释,其中一些关键的配置如下。

运行:$ cat /etc/dnsmasq.conf

 

# 服务监听的网络接口地址

# If you want dnsmasq to listen for DHCP and DNS requests only on

# specified interfaces (and the loopback) give the name of the

# interface (eg eth0) here.

# Repeat the line for more than one interface.

#interface=

# Or you can specify which interface _not_ to listen on

#except-interface=

# Or which to listen on by address (remember to include 127.0.0.1 if

# you use this.)

listen-address=192.168.1.132,127.0.0.1

# dhcp动态分配的地址范围,自动分配50-150ip段,有效期48小时

# Uncomment this to enable the integrated DHCP server, you need

# to supply the range of addresses available for lease and optionally a lease time

dhcp-range=192.168.1.50,192.168.1.150,48h

# dhcp服务的静态绑定

# dhcp-host的配置方式有很多种,这里使用的是:[client端MAC地址] + [分配的IP]+ [主机名]

# Always set the name and ipaddr of the host with hardware address

# dhcp-host=00:0C:29:5E:F2:6F,192.168.1.201

# dhcp-host=00:0C:29:5E:F2:6F,192.168.1.201,infinite 无限租期

dhcp-host=00:0C:29:5E:F2:6F,192.168.1.201,os02

dhcp-host=00:0C:29:15:63:CF,192.168.1.202,os03

# dhcp服务的其它几种绑定方式

# Always allocate the host with ethernet address 11:22:33:44:55:66

# The IP address 192.168.0.60

# 绑定网卡地址对应ip地址,用的是host的方式,类似在hosts文件写一个host name 对应一个ip,所以这个不是arp绑定,要区分。

# dhcp-host=11:22:33:44:55:66,192.168.1.60

# Always set the name of the host with hardware address

# 11:22:33:44:55:66 to be "fred"

# 绑定mac地址对应一个host name ,我个人觉得绑定mac对应ip就足够了,绑定对应名字比较少见

# dhcp-host=11:22:33:44:55:66,fred

# Always give the host with ethernet address 11:22:33:44:55:66

# the name fred and IP address 192.168.0.60 and lease time 45 minutes

# 这个是组合版,绑定某个mac对应fred名字,然后加上一个ip分配,并设置租约,这个只能说是灵活配置的参考,没啥实际意义

# dhcp-host=11:22:33:44:55:66,fred,192.168.0.60,45m

# Give a host with ethernet address 11:22:33:44:55:66 or

# 12:34:56:78:90:12 the IP address 192.168.0.60. Dnsmasq will assume

# that these two ethernet interfaces will never be in use at the same

# time, and give the IP address to the second, even if it is already

# in use by the first. Useful for laptops with wired and wireless

# addresses.

# 绑定一个ip对应多mac地址,用途场景存在于实验室和无线网络,我想只是为了让2块网卡用同一个ip这样单纯而纯洁的需求而已[不常用]

# dhcp-host=11:22:33:44:55:66,12:34:56:78:90:12,192.168.0.60

# Give the machine which says its name is "bert" IP address

# 192.168.0.70 and an infinite lease

# 绑定名字对应ip,并且给了一个新参数,无限租约

# dhcp-host=bert,192.168.0.70,infinite

# Always give the host with client identifier 01:02:02:04

# the IP address 192.168.0.60

# 给予一个特殊标识符对应ip,用途不明

# dhcp-host=id:01:02:02:04,192.168.0.60

# Always give the host with client identifier "marjorie"

# the IP address 192.168.0.60

# 跟上一条类似,只是标识符还支持普通字符字串

# dhcp-host=id:marjorie,192.168.0.60

# 通过/etc/hosts来分配对应的hostname

# Enable the address given for "judge" in /etc/hosts

# to be given to a machine presenting the name "judge" when

# it asks for a DHCP lease.

# dhcp-host=judge

# 忽略下面MAC地址的DHCP请求,不分配ip

# Never offer DHCP service to a machine whose ethernet

# address is 11:22:33:44:55:66

#dhcp-host=11:22:33:44:55:66,ignore

# If this line is uncommented, dnsmasq will read /etc/ethers and act

# on the ethernet-address/IP pairs found there just as if they had

# been given as --dhcp-host options. Useful if you keep

# MAC-address/host mappings there for other purposes.

# 使用额外的文件代替主配置文件来处理dhcp-host的匹配,这个主要为了方便管理,将所有需要用到的dhcp-host配置都放进/etc/ethers

# 设置默认租期

# Set the limit on DHCP leases, the default is 150

#dhcp-lease-max=150

# 租期保存在下面文件

# The DHCP server needs somewhere on disk to keep its lease database.

# This defaults to a sane location, but if you want to change it, use

# the line below.

#dhcp-leasefile=/var/lib/dnsmasq/dnsmasq.leases

# Set this (and domain: see below) if you want to have a domain

# automatically added to simple names in a hosts-file.

# 自动给hosts的域名增加一个简单的名字,搭配下面的domain用的[不常用]

expand-hosts

# dhcp所在的域

# Set the domain for dnsmasq. this is optional, but if it is set, it

# does the following things.

# 1) Allows DHCP hosts to have fully qualified domain names, as long

#     as the domain part matches this setting.

# 2) Sets the "domain" DHCP option thereby potentially setting the

#    domain of all systems configured by DHCP

# 3) Provides the domain part for "expand-hosts"

domain=hi-linux.com

# 设置默认路由出口

# dhcp-option遵循RFC 2132(Options and BOOTP Vendor Extensions),可以通过dnsmasq --help dhcp来查看具体的配置

# 很多高级的配置,如iSCSI连接配置等同样可以由RFC 2132定义的dhcp-option中给出。

# option 3为default route

# Override the default route supplied by dnsmasq, which assumes the

# router is the same machine as the one running dnsmasq.

dhcp-option=3,192.168.1.1

# 设置NTP Server.这是使用option name而非选项名来进行设置

# Set the NTP time server addresses to 192.168.0.4 and 10.10.0.5

#dhcp-option=option:ntp-server,192.168.0.4,10.10.0.5

 

注意:当为某一MAC地址同时静态分配主机名和IP时,如果写到两条dhcp-host选项里(如下所示),则只会生效后面的一条。正确的选项写法(如上配置)。

dhcp-host=00:0C:29:5E:F2:6F,192.168.1.201

dhcp-host=00:0C:29:5E:F2:6F,os02

 

下面在客户端进行测试

1.重新启动dnsmasq服务(server的IP为192.168.1.132)

由于之前测试中客户端网卡已经申请了DHCP租期。所以这里需要修改租期文件,让客户端重新获得IP和hostname。

DNSmasq服务的租期信息存储在/var/lib/dnsmasq/dnsmasq.leases这个文件。如果这个租约需要被更快地移除,您可以停止DNSmasq服务,从dnsmasq.leases文件中移除这个租约,然后再启动这个服务。

$ /etc/init.d/dnsmasq stop

$ vim /var/lib/dnsmasq/dnsmasq.leases

# 删除对应的租约信息

1400240493 00:0c:29:5e:f2:6f 192.168.1.143 os02 *

1400240498 00:0c:29:15:63:cf 192.168.1.52 os01 *

$ /etc/init.d/dnsmasq restart

 

2.确保网络接口配置使用dhcp方式

$ cat /etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE="eth1"

BOOTPROTO=dhcp

IPV6INIT=no

NM_CONTROLLED=no

ONBOOT="yes"

TYPE="Ethernet"

 

3.重启网络服务

$ service network restart

Shutting down interface eth0:                              [  OK  ]

Shutting down loopback interface:                          [  OK  ]

Bringing up loopback interface:                            [  OK  ]

Bringing up interface eth0:  

Determining IP information for eth1... done.               [  OK  ]

 

4.检查IP地址

$ ifconfig

使用Dnsmasq部署DHCP服务

 

5.检查默认路由

$ route -n

使用Dnsmasq部署DHCP服务

 

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