arp检测

我的ARP检测日志如下：
= 2011-04-17 22:42:51 Query: 192.168.1.12 00-30-67-7b-c5-48 50
= 2011-04-17 22:52:26 Query: 192.168.1.41 e0-cb-4e-ea-8e-b1 50
= 2011-04-17 22:53:10 Query: 192.168.1.12 00-30-67-7b-c5-48 100
= 2011-04-17 22:54:11 Query: 192.168.1.41 e0-cb-4e-ea-8e-b1 100
= 2011-04-17 23:04:01 Query: 192.168.1.12 00-30-67-7b-c5-48 150
= 2011-04-17 23:11:38 Query: 192.168.1.12 00-30-67-7b-c5-48 200
= 2011-04-17 23:19:37 Query: 192.168.1.12 00-30-67-7b-c5-48 250
= 2011-04-17 23:27:36 Query: 192.168.1.12 00-30-67-7b-c5-48 300
= 2011-04-17 23:33:41 Query: 192.168.1.123 bc-ae-c5-bf-11-81 50
2011-04-17 23:48:50 Alteration_IP: bc-ae-c5-bf-11-81 changed from 192.168.1.80 to 192.168.1.123
2011-04-17 23:49:00 Alteration_IP: 00-0b-2f-48-75-74 changed from 192.168.1.96 to 192.168.1.227
请问有攻击吗？后面的50 100 150 300是什么意思？

我是来学习的，你可以安装个彩影的ARP防火墙，还不错。