鸟哥学习笔记---DHCP

 

1.到服务器的日志文件中查找该用户是否曾经租用过某个IP，若有且该IP目前无人使用，则提供此IP给客户端。  2.若配置文件针对该IP地址提供特定的固定IP时，提供该固定IP给客户端。  3.若不符合上面的两个条件，则随机选取当前没有被使用的IP参数给客户端，并记录下来。

 

获取MAC地址：

[root@Centosszm ~]# ifconfig | grep HW

eth0      Link encap:Ethernet  HWaddr 00:0C:29:24:C2:A5

[root@Centosszm ~]# arp -n

Address                  HWtype  HWaddress           Flags Mask            Iface

192.168.179.1            ether   00:50:56:c0:00:08   C                     eth0

192.168.179.2            ether   00:50:56:eb:ab:2c   C                     eth0

0.5个租约时会发出续约，0.85个租约也一样会发出续约。服务器端67端口监听，客户端：68端口请求。

 

 

 

 

[root@Centosszm ~]# rpm -ql dhcp | grep conf

/etc/dhcp/dhcpd.conf

/etc/dhcp/dhcpd6.conf

/etc/sysconfig/dhcpd

/etc/sysconfig/dhcpd6

/etc/sysconfig/dhcrelay

/usr/share/doc/dhcp-4.1.1/dhcpd-conf-to-ldap

/usr/share/doc/dhcp-4.1.1/dhcpd.conf.sample

/usr/share/doc/dhcp-4.1.1/dhcpd6.conf.sample

/usr/share/man/man5/dhcpd.conf.5.gz

 

 

[root@Centosszm ~]# vi /etc/dhcp/dhcpd.conf

CentOS 5.x以前，配置文件都被存储于/etc/dhcpd.conf，新版的才放置于此处。

[root@Centosszm ~]# vi /var/lib/dhcpd/dhcpd.leases

 

[root@Centosszm ~]# /usr/sbin/dhcpd

 

[root@Centosszm ~]# cat /etc/dhcp/dhcpd.conf

# dhcpd.conf

#

# Sample configuration file for ISC dhcpd

#

 

# option definitions common to all supported networks...

option domain-name "example.org"; #域名，加域名后缀用

option domain-name-servers ns1.example.org, ns2.example.org; #DNSIP

 

default-lease-time 600; #默认租约时间

max-lease-time 7200;   #最大租约时间

#客户端通过dhcpd服务器来更新DNS相关的信息

ignore client-updates

 

# Use this to enble / disable dynamic dns updates globally.

#ddns-update-style none; #更新主机名与IP的对应关系

 

# 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 {

}

 

# 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;

  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;

  option domain-name "internal.example.org";

  option routers 10.5.5.1;

  option broadcast-address 10.5.5.31;

  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 informati                                                                                        on

# 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 addresse                                                                                        s

# should not also be listed as being available for dynamic assignment.

# Hosts for which fixed IP addresses have been specified can boot usin                                                                                        g

# BOOTP or DHCP.   Hosts for which no fixed address is specified can o                                                                                        nly

# 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 fla                                                                                        g

# set.

host fantasia {

  hardware ethernet 08:00:07:26:c0:a5;

  fixed-address fantasia.fugue.com;

}

 

# 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;

  }

}

[root@Centosszm ~]# vim /etc/dhcp/dhcpd.conf

option domain-name "test.com";

option domain-name-servers 192.168.179.2;

 

subnet 192.168.179.0 netmsk 255.255.255.0 {

        range 192.168.179.4 192.168.179.200;

        option routers 192.168.179.2;

}

 

[root@Centosszm ~]# cat /etc/sysconfig/dhcpd

# Command line options here

DHCPDARGS="eth0"

上一条命令在CentOS 5.x以后的版本上已经不需要了，因为新版本的DHCP会主动分析服务器与实际的dhcpd.conf设置，如果两者无法吻合，就会有错误提示，人性化多了。

 

 

[root@Centosszm ~]# service dhcpd start

Starting dhcpd:                                            [  OK  ]

如果启动不了，可以查看下面的内容：

[root@Centosszm ~]# tailf /var/log/messages

 

Mar 29 14:29:58 Centosszm dhcpd: Internet Systems Consortium DHCP Server 4.1.1-P1

Mar 29 14:29:58 Centosszm dhcpd: Copyright 2004-2010 Internet Systems Consortium.

Mar 29 14:29:58 Centosszm dhcpd: Copyright 2004-2010 Internet Systems Consortium.

Mar 29 14:29:58 Centosszm dhcpd: All rights reserved.

Mar 29 14:29:58 Centosszm dhcpd: For info, please visit https://www.isc.org/software/dhcp/

Mar 29 14:29:58 Centosszm dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file

Mar 29 14:29:58 Centosszm dhcpd: Internet Systems Consortium DHCP Server 4.1.1-P1

Mar 29 14:29:58 Centosszm dhcpd: Copyright 2004-2010 Internet Systems Consortium.

Mar 29 14:29:58 Centosszm dhcpd: All rights reserved.

Mar 29 14:29:58 Centosszm dhcpd: For info, please visit https://www.isc.org/software/dhcp/

Mar 29 14:29:58 Centosszm dhcpd: Wrote 0 class decls to leases file.

Mar 29 14:29:58 Centosszm dhcpd: Wrote 0 deleted host decls to leases file.

Mar 29 14:29:58 Centosszm dhcpd: Wrote 0 new dynamic host decls to leases file.

Mar 29 14:29:58 Centosszm dhcpd: Wrote 0 leases to leases file.

Mar 29 14:29:58 Centosszm dhcpd: Listening on LPF/eth0/00:0c:29:24:c2:a5/192.168.179.0/24

Mar 29 14:29:58 Centosszm dhcpd: Sending on   LPF/eth0/00:0c:29:24:c2:a5/192.168.179.0/24

Mar 29 14:29:58 Centosszm dhcpd: Sending on   Socket/fallback/fallback-net

/etc/hosts会影响内部计算机在连接阶段的等待时间。

 

客户端机szm:

 [root@szm ~]# cat /etc/resolv.conf

; generated by /sbin/dhclient-script

search test.com

nameserver 192.168.179.2

 

[root@szm ~]# route -n

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

192.168.179.0   0.0.0.0         255.255.255.0   U     0      0        0 eth1

192.168.111.0   0.0.0.0         255.255.255.0   U     0      0        0 eth1

169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth1

0.0.0.0         192.168.179.2   0.0.0.0         UG    0      0        0 eth1

 

[root@szm ~]# netstat -tulnp | grep dhc

udp        0      0 0.0.0.0:68                  0.0.0.0:*        3213/dhclient

 

[root@szm ~]# cat /var/lib/dhclient/dhclient-eth1.leases

lease {

  interface "eth1";

  fixed-address 192.168.179.143;

  option subnet-mask 255.255.255.0;

  option routers 192.168.179.2;

  option dhcp-lease-time 600;

  option dhcp-message-type 5;

  option domain-name-servers 192.168.179.2;

  option dhcp-server-identifier 192.168.179.7;

  option domain-name "test.com";

  renew 5 2013/03/29 07:16:18;

  rebind 5 2013/03/29 07:21:07;

  expire 5 2013/03/29 07:22:22;

}

    上面这个地方会记录客户端曾经获得的IP地址，客户端会向DHCP申请这个IP地址，如果想要不同的IP地址，那就把想要的Ip地址取代上面的IP地址就可以了

     如果一个局域网内有两台DHCP，若第一次取得DHCP1服务器的IP后，以后重新启动网络，都只会取得DHCP1的网络参数，这是为什么呢？[root@szm ~]# cat /var/lib/dhclient/dhclient-eth1.leases，删除后就是先到先得的方式了。

 

服务器端记录IP分配情况：

[root@Centosszm ~]# 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-4.1.1-P1

 

lease 192.168.179.143 {

  starts 5 2013/03/29 07:01:09;

  ends 5 2013/03/29 07:11:09;

  tstp 5 2013/03/29 07:11:09;

  cltt 5 2013/03/29 07:01:09;

  binding state active;

  next binding state free;

  hardware ethernet 00:0c:29:e2:84:0d;

}

server-duid "\000\001\000\001\030\347\361f\000\014)$\302\245";

 

lease 192.168.179.143 {

  starts 5 2013/03/29 07:05:21;

  ends 5 2013/03/29 07:15:21;

  cltt 5 2013/03/29 07:05:21;

  binding state active;

  next binding state free;

  hardware ethernet 00:0c:29:e2:84:0d;

}

lease 192.168.179.143 {

  starts 5 2013/03/29 07:09:08;

  ends 5 2013/03/29 07:19:08;

  cltt 5 2013/03/29 07:09:08;

  binding state active;

  next binding state free;

  hardware ethernet 00:0c:29:e2:84:0d;

}

lease 192.168.179.143 {

  starts 5 2013/03/29 07:12:22;

  ends 5 2013/03/29 07:22:22;

  cltt 5 2013/03/29 07:12:22;

  binding state active;

  next binding state free;

  hardware ethernet 00:0c:29:e2:84:0d;

}

lease 192.168.179.88 {

  starts 5 2013/03/29 07:16:17;

  ends 5 2013/03/29 07:26:17;

  cltt 5 2013/03/29 07:16:17;

  binding state active;

  next binding state free;

  hardware ethernet 00:0c:29:e2:84:0d;

}

 

让大量PC都具有固定IP的脚本：arp -n

Widnows获得:netsh interface ip set address xxx

 

    已经知道了客户端的MAC地址了，如果客户端的主机支持一些电源标准，并且改客户端主机所使用的网卡与主板支持网络唤醒功能，我们就可以通过网络来让客户端计算机开机了。

[root@Centosszm ~]# ether-wake -i 11:22:33:44:55:66