使用nc检测udp端口是否可以正常通讯

netcat，很少用，总把这东西忘了，做个记录，这玩意也有windows版的http://joncraton.org/blog/46。

[root@domU-12-33-39-01-6C-F1:~] nc -h

usage: nc [-46DdhklnrStUuvzC] [-i interval] [-p source_port]

[-s source_ip_address] [-T ToS] [-w timeout] [-X proxy_version]

[-x proxy_address[:port]] [hostname] [port[s]]

Command Summary:

-4 Use IPv4

-6 Use IPv6

-D Enable the debug socket option

-d Detach from stdin

-h This help text

-i secs Delay interval for lines sent, ports scanned

-k Keep inbound sockets open for multiple connects

-l Listen mode, for inbound connects

-n Suppress name/port resolutions

-p port Specify local port for remote connects

-r Randomize remote ports

-s addr Local source address

-T ToS Set IP Type of Service

-C Send CRLF as line-ending

-t Answer TELNET negotiation

-U Use UNIX domain socket

-u UDP mode

-v Verbose

-w secs Timeout for connects and final net reads

-X proto Proxy protocol: “4″, “5″ (SOCKS) or “connect”

-x addr[:port] Specify proxy address and port

-z Zero-I/O mode [used for scanning]

Port numbers can be individual or ranges: lo-hi [inclusive]

用来测试upd端口是否正常

a端：nc -ul 161

b端: nc -u a.a.a.a 161

在b端随便输入字符，看是否能够传到a端。