D:\netcat-win32-1.12>nc -h
[v1.12 NT http://eternallybored.org/misc/netcat/]
connect to somewhere: nc [-options] hostname port[s] [ports] ...
listen for inbound: nc -l -p port [options] [hostname] [port]
options:
-d detach from console, background mode
-e prog inbound program to exec [dangerous!!]
-g gateway source-routing hop point[s], up to 8
-G num source-routing pointer: 4, 8, 12, ...
-h this cruft
-i secs delay interval for lines sent, ports scanned
-l listen mode, for inbound connects
-L listen harder, re-listen on socket close
-n numeric-only IP addresses, no DNS
-o file hex dump of traffic
-p port local port number
-r randomize local and remote ports
-s addr local source address
-t answer TELNET negotiation
-c send CRLF instead of just LF
-u UDP mode
-v verbose [use twice to be more verbose]
-w secs timeout for connects and final net reads
-z zero-I/O mode [used for scanning]
port numbers can be individual or ranges: m-n [inclusive]
测试tcp端口：
>nc -z -v 192.118.1.1 9999
测试ucp端口：
nc -z -v -u 192.118.1.1 9999
tcp主机连通性测试：
服务器上执行：nc -l -p <端口号> -v
本地执行：nc <服务器端 IP 地址> <端口号>
udp主机连通性测试：
服务器上执行：nc -lu -p <端口号> -v
本地执行：nc -u <服务器端IP地址> <端口号>
