下载windows版nmap 

cd C:\Program Files (x86)\Nmap

使用 ncat 命令测试 UDP 端口连接
使用 ncat 命令测试 UDP 端口连通性的语法如下：

ncat -z -v -u [主机名/IP 地址] [端口号]
成功连接示例：

C:\Program Files (x86)\Nmap>ncat -z -v -u ntp.aliyun 123
Ncat: Version 7.80 ( https://nmap/ncat )
Ncat: Connected to 203.107.6.88:123.
Ncat: UDP packet sent successfully
Ncat: 1 bytes sent, 0 bytes received in 2.11 seconds.

C:\Program Files (x86)\Nmap>ncat -z -v -u localhost 161
Ncat: Version 7.80 ( https://nmap/ncat )
Ncat: Connected to ::1:161.
Ncat: UDP packet sent successfully
Ncat: 1 bytes sent, 0 bytes received in 2.11 seconds.

C:\Program Files (x86)\Nmap>ncat -z -v -u localhost 162
Ncat: Version 7.80 ( https://nmap/ncat )
Ncat: Connected to ::1:162.
Ncat: 远程主机强迫关闭了一个现有的连接。 .