一、 内部帮助
root@router:~# nc
BusyBox v1.28.1 (2018-04-03 17:06:42 CST) multi-call binary.
Usage: nc [OPTIONS] HOST PORT - connect
nc [OPTIONS] -l -p PORT [HOST] [PORT] - listen
-e PROG Run PROG after connect (must be last)
-l Listen mode, for inbound connects
-lk With -e, provides persistent server
-p PORT Local port
-s ADDR Local address
-w SEC Timeout for connects and final net reads
-i SEC Delay interval for lines sent
-n Don't do DNS resolution
-u UDP mode
-v Verbose
-o FILE Hex dump traffic
-z Zero-I/O mode (scanning)
二、Linux的网卡162.168.8.1启动tcp服务器，监听端口20000
三、Linux的网卡162.168.8.1启动udp服务器，监听端口20000
四、Linux的网卡162.168.8.1启动udp客户端，连接udp服务器162.168.8.113的端口10000