DHCP：查看已经分配出去的IP地址

Posted on: 2017年3月1日 2017年3月1日
Categories: Red Hat, RHEL
Tags: /var/lib/dhcpd/dhcpd.leases, DHCPD, IP, 已分配的

我们知道，DHCP可以动态的分配IP地址。
但是，我们怎么知道DHCP到底分配出了哪些地址？难道去网段里面去扫描？

这当然是可行的方法之一，但是，有更好的方法。

DHCPD服务，会将已经分配出去的IP的相关信息记录在一个文件里面：/var/lib/dhcpd/dhcpd.leases

具体如下：

[root@center-me ~]# 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 10.158.1.104 {
  starts 3 2017/02/15 06:43:38;
  ends 3 2017/02/15 12:43:38;
  tstp 3 2017/02/15 12:43:38;
  cltt 3 2017/02/15 06:43:38;
  binding state free;
  hardware ethernet 00:50:56:84:67:c1;
}
lease 10.158.1.103 {
  starts 3 2017/02/15 06:52:30;
  ends 3 2017/02/15 12:52:30;
  tstp 3 2017/02/15 12:52:30;
  cltt 3 2017/02/15 06:52:30;
  binding state free;
  hardware ethernet 00:50:56:84:1d:b1;
}
lease 10.158.1.105 {
  starts 3 2017/02/15 06:56:05;
  ends 3 2017/02/15 12:56:05;
  tstp 3 2017/02/15 12:56:05;
  cltt 3 2017/02/15 06:56:05;
  binding state free;
  hardware ethernet 00:50:56:84:00:8a;
}
lease 10.158.1.106 {
  starts 4 2017/02/16 03:00:06;
  ends 4 2017/02/16 09:00:06;
  tstp 4 2017/02/16 09:00:06;
  cltt 4 2017/02/16 03:00:06;
  binding state free;
  hardware ethernet 00:50:56:84:22:fa;
  set vendorclass = "PXEClient:Arch:00000:UNDI:002001";
}
lease 10.158.1.107 {
  starts 5 2017/02/17 09:26:32;
  ends 5 2017/02/17 15:26:32;
  tstp 5 2017/02/17 15:26:32;
  cltt 5 2017/02/17 09:26:32;
  binding state free;
  hardware ethernet 00:50:56:a6:0c:5b;
}
lease 10.158.1.108 {
  starts 1 2017/02/20 03:16:36;
  ends 1 2017/02/20 09:16:36;
  tstp 1 2017/02/20 09:16:36;
  cltt 1 2017/02/20 03:16:36;
  binding state free;
  hardware ethernet 00:50:56:84:62:bd;
  uid "\001\000PV\204b\275";
  set vendorclass = "MSFT 5.0";
}
lease 10.158.1.109 {
  starts 1 2017/02/20 05:50:30;
  ends 1 2017/02/20 11:50:30;
  tstp 1 2017/02/20 11:50:30;
  cltt 1 2017/02/20 05:50:30;
  binding state free;
  hardware ethernet 00:50:56:84:71:71;
  set vendorclass = "PXEClient:Arch:00000:UNDI:002001";
}
lease 10.158.1.117 {
  starts 5 2017/02/24 05:21:50;
  ends 5 2017/02/24 11:21:50;
  tstp 5 2017/02/24 11:21:50;
  cltt 5 2017/02/24 05:21:50;
  binding state free;
  hardware ethernet 00:50:56:84:00:c8;
}
lease 10.158.1.121 {
  starts 5 2017/02/24 05:41:18;
  ends 5 2017/02/24 11:41:18;
  tstp 5 2017/02/24 11:41:18;
  cltt 5 2017/02/24 05:41:18;
  binding state free;
  hardware ethernet 00:50:56:84:01:8e;
}
lease 10.158.1.116 {
  starts 5 2017/02/24 05:57:48;
  ends 5 2017/02/24 11:57:48;
  tstp 5 2017/02/24 11:57:48;
  cltt 5 2017/02/24 05:57:48;
  binding state free;
  hardware ethernet 00:50:56:84:2b:e2;
}
lease 10.158.1.119 {
  starts 5 2017/02/24 06:02:21;
  ends 5 2017/02/24 12:02:21;
  tstp 5 2017/02/24 12:02:21;
  cltt 5 2017/02/24 06:02:21;
  binding state free;
  hardware ethernet 00:50:56:84:5a:79;
}
lease 10.158.1.122 {
  starts 5 2017/02/24 06:10:04;
  ends 5 2017/02/24 12:10:04;
  tstp 5 2017/02/24 12:10:04;
  cltt 5 2017/02/24 06:10:04;
  binding state free;
  hardware ethernet 00:50:56:84:60:d9;
}
lease 10.158.1.101 {
  starts 2 2017/02/28 20:16:33;
  ends 3 2017/03/01 02:16:33;
  cltt 2 2017/02/28 20:16:33;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:50:56:84:6a:7d;
  uid "\001\000PV\204j}";
  set vendorclass = "udhcp 1.23.1";
  client-hostname "boot2docker";
}
lease 10.158.1.102 {
  starts 2 2017/02/28 23:15:25;
  ends 3 2017/03/01 05:15:25;
  cltt 2 2017/02/28 23:15:25;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:50:56:02:01:00;
  uid "\001\000PV\002\001\000";
  set vendorclass = "MSFT 5.0";
  client-hostname "WIN-PVEA1SONOMA";
}
server-duid "\000\001\000\001 6\240\236\000PV\204\013`";

lease 10.158.1.101 {
  starts 2 2017/02/28 23:16:33;
  ends 3 2017/03/01 05:16:33;
  cltt 2 2017/02/28 23:16:33;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:50:56:84:6a:7d;
  uid "\001\000PV\204j}";
  set vendorclass = "udhcp 1.23.1";
  client-hostname "boot2docker";
}
[root@center-me ~]# 
[root@center-me ~]#

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

[root@center-me ~]# 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 10.158.1.104 {

starts 3 2017/02/15 06:43:38;

ends 3 2017/02/15 12:43:38;

tstp 3 2017/02/15 12:43:38;

cltt 3 2017/02/15 06:43:38;

binding state free;

hardware ethernet 00:50:56:84:67:c1;

}

lease 10.158.1.103 {

starts 3 2017/02/15 06:52:30;

ends 3 2017/02/15 12:52:30;

tstp 3 2017/02/15 12:52:30;

cltt 3 2017/02/15 06:52:30;

binding state free;

hardware ethernet 00:50:56:84:1d:b1;

}

lease 10.158.1.105 {

starts 3 2017/02/15 06:56:05;

ends 3 2017/02/15 12:56:05;

tstp 3 2017/02/15 12:56:05;

cltt 3 2017/02/15 06:56:05;

binding state free;

hardware ethernet 00:50:56:84:00:8a;

}

lease 10.158.1.106 {

starts 4 2017/02/16 03:00:06;

ends 4 2017/02/16 09:00:06;

tstp 4 2017/02/16 09:00:06;

cltt 4 2017/02/16 03:00:06;

binding state free;

hardware ethernet 00:50:56:84:22:fa;

set vendorclass = "PXEClient:Arch:00000:UNDI:002001";

}

lease 10.158.1.107 {

starts 5 2017/02/17 09:26:32;

ends 5 2017/02/17 15:26:32;

tstp 5 2017/02/17 15:26:32;

cltt 5 2017/02/17 09:26:32;

binding state free;

hardware ethernet 00:50:56:a6:0c:5b;

}

lease 10.158.1.108 {

starts 1 2017/02/20 03:16:36;

ends 1 2017/02/20 09:16:36;

tstp 1 2017/02/20 09:16:36;

cltt 1 2017/02/20 03:16:36;

binding state free;

hardware ethernet 00:50:56:84:62:bd;

uid "\001\000PV\204b\275";

set vendorclass = "MSFT 5.0";

}

lease 10.158.1.109 {

starts 1 2017/02/20 05:50:30;

ends 1 2017/02/20 11:50:30;

tstp 1 2017/02/20 11:50:30;

cltt 1 2017/02/20 05:50:30;

binding state free;

hardware ethernet 00:50:56:84:71:71;

set vendorclass = "PXEClient:Arch:00000:UNDI:002001";

}

lease 10.158.1.117 {

starts 5 2017/02/24 05:21:50;

ends 5 2017/02/24 11:21:50;

tstp 5 2017/02/24 11:21:50;

cltt 5 2017/02/24 05:21:50;

binding state free;

hardware ethernet 00:50:56:84:00:c8;

}

lease 10.158.1.121 {

starts 5 2017/02/24 05:41:18;

ends 5 2017/02/24 11:41:18;

tstp 5 2017/02/24 11:41:18;

cltt 5 2017/02/24 05:41:18;

binding state free;

hardware ethernet 00:50:56:84:01:8e;

}

lease 10.158.1.116 {

starts 5 2017/02/24 05:57:48;

ends 5 2017/02/24 11:57:48;

tstp 5 2017/02/24 11:57:48;

cltt 5 2017/02/24 05:57:48;

binding state free;

hardware ethernet 00:50:56:84:2b:e2;

}

lease 10.158.1.119 {

starts 5 2017/02/24 06:02:21;

ends 5 2017/02/24 12:02:21;

tstp 5 2017/02/24 12:02:21;

cltt 5 2017/02/24 06:02:21;

binding state free;

hardware ethernet 00:50:56:84:5a:79;

}

lease 10.158.1.122 {

starts 5 2017/02/24 06:10:04;

ends 5 2017/02/24 12:10:04;

tstp 5 2017/02/24 12:10:04;

cltt 5 2017/02/24 06:10:04;

binding state free;

hardware ethernet 00:50:56:84:60:d9;

}

lease 10.158.1.101 {

starts 2 2017/02/28 20:16:33;

ends 3 2017/03/01 02:16:33;

cltt 2 2017/02/28 20:16:33;

binding state active;

next binding state free;

rewind binding state free;

hardware ethernet 00:50:56:84:6a:7d;

uid "\001\000PV\204j}";

set vendorclass = "udhcp 1.23.1";

client-hostname "boot2docker";

}

lease 10.158.1.102 {

starts 2 2017/02/28 23:15:25;

ends 3 2017/03/01 05:15:25;

cltt 2 2017/02/28 23:15:25;

binding state active;

next binding state free;

rewind binding state free;

hardware ethernet 00:50:56:02:01:00;

uid "\001\000PV\002\001\000";

set vendorclass = "MSFT 5.0";

client-hostname "WIN-PVEA1SONOMA";

}

server-duid "\000\001\000\001 6\240\236\000PV\204\013`";

lease 10.158.1.101 {

starts 2 2017/02/28 23:16:33;

ends 3 2017/03/01 05:16:33;

cltt 2 2017/02/28 23:16:33;

binding state active;

next binding state free;

rewind binding state free;

hardware ethernet 00:50:56:84:6a:7d;

uid "\001\000PV\204j}";

set vendorclass = "udhcp 1.23.1";

client-hostname "boot2docker";

}

[root@center-me ~]#

可以看到，改文件中可能会有重复的记录条目。
更清楚的看到，如下：

[root@center-me ~]# cat /var/lib/dhcpd/dhcpd.leases | grep lease | cut -d' ' -f2 | grep -v -E "The|This"
10.158.1.104
10.158.1.103
10.158.1.105
10.158.1.106
10.158.1.107
10.158.1.108
10.158.1.109
10.158.1.117
10.158.1.121
10.158.1.116
10.158.1.119
10.158.1.122
10.158.1.101
10.158.1.102
10.158.1.101
[root@center-me ~]#

[root@center-me ~]# cat /var/lib/dhcpd/dhcpd.leases | grep lease | cut -d' ' -f2 | grep -v -E "The|This"

10.158.1.104

10.158.1.103

10.158.1.105

10.158.1.106

10.158.1.107

10.158.1.108

10.158.1.109

10.158.1.117

10.158.1.121

10.158.1.116

10.158.1.119

10.158.1.122

10.158.1.101

10.158.1.102

10.158.1.101

[root@center-me ~]#

可以看到【101】是重复的。

要想筛选出来不重复的IP列表可以通过脚本或者一句命令实现：

[root@center-me ~]# cat /var/lib/dhcpd/dhcpd.leases | grep lease | cut -d' ' -f2 | grep -v -E "The|This" | sort -u
10.158.1.101
10.158.1.102
10.158.1.103
10.158.1.104
10.158.1.105
10.158.1.106
10.158.1.107
10.158.1.108
10.158.1.109
10.158.1.116
10.158.1.117
10.158.1.119
10.158.1.121
10.158.1.122
[root@center-me ~]#

10.158.1.101

10.158.1.102

10.158.1.103

10.158.1.104

10.158.1.105

10.158.1.106

10.158.1.107

10.158.1.108

10.158.1.109

10.158.1.116

10.158.1.117

10.158.1.119

10.158.1.121

10.158.1.122

[root@center-me ~]#

————————————
Done。

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Adamhuan

Waiting for the moment，热衷数据库技术、Linux/Unix，以及心理学、精神分析等...(etc)，习惯用文字（符号）阐述自己对世界的理解与认知。 ———————— 微信公众号：Leviathan2020 博客：http://www.d-prototype.com

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