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macOS 使用 arping 扫描 ip 冲突

November 7, 2022 • Read: 3 • 技术

最近工作网络不稳定,多个常用 IP 出现冲突,就连 DHCP 获取到的 IP 也会立刻冲突,原因等待相关人员去解决,今天简单记录 macOS 下 IP 冲突检测的原因。

一般检查 IP 是否被占用的方法是使用 ping

$ ping 119.29.29.29
PING 119.29.29.29 (119.29.29.29): 56 data bytes
64 bytes from 119.29.29.29: icmp_seq=0 ttl=50 time=14.477 ms
64 bytes from 119.29.29.29: icmp_seq=1 ttl=50 time=15.033 ms
64 bytes from 119.29.29.29: icmp_seq=2 ttl=50 time=15.330 ms
^C
--- 119.29.29.29 ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 14.477/14.947/15.330/0.354 ms

但是这种方法看不到ip冲突,如果出现多个机器占用同个 IP,可以利用arp协议查一下 MAC 地址:

# macOS 下这样安装
$ brew install arping
# 使用 alias 定义快速使用别名
$ alias arping='sudo /opt/homebrew/opt/arping/sbin/arping'

另外发现 m1 下的 brew 安装 arping 默认不会进入 PATH ,因此在这里手动设定一个别名,方便使用。

之后扫描,如果出现 IP 冲突,可以看到有多个 MAC 地址回应:

$ sudo /opt/homebrew/opt/arping/sbin/arping 192.168.5.79
Password:
ARPING 192.168.5.79
60 bytes from 6a:f2:77:bd:bf:16 (192.168.5.79): index=0 time=463.000 usec
60 bytes from 6a:29:af:20:80:7f (192.168.5.79): index=1 time=1.002 msec
60 bytes from 6a:f2:77:bd:bf:16 (192.168.5.79): index=2 time=582.000 usec
60 bytes from 6a:29:af:20:80:7f (192.168.5.79): index=3 time=1.182 msec
60 bytes from 6a:f2:77:bd:bf:16 (192.168.5.79): index=4 time=658.000 usec
60 bytes from 6a:29:af:20:80:7f (192.168.5.79): index=5 time=1.117 msec
60 bytes from 6a:f2:77:bd:bf:16 (192.168.5.79): index=6 time=772.000 usec
60 bytes from 6a:29:af:20:80:7f (192.168.5.79): index=7 time=1.096 msec
^C
--- 192.168.5.79 statistics ---
4 packets transmitted, 8 packets received,   0% unanswered (4 extra)
rtt min/avg/max/std-dev = 0.463/0.859/1.182/0.257 ms

还可以通过 arping 来查看是否 IP 被占用,有些机器会禁止 PING 检测,使用 arp 这类二层协议检测占用情况会更准确些。

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