首先安装（Ubuntu系统）
apt update apt-get install netcat
命令格式 具体用法
nc -h OpenBSD netcat (Debian patchlevel 1.218-4ubuntu1) usage: nc [-46CDdFhklNnrStUuvZz] [-I length] [-i interval] [-M ttl] [-m minttl] [-O length] [-P proxy_username] [-p source_port] [-q seconds] [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit] [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]] [destination] [port] Command Summary: -4 Use IPv4 -6 Use IPv6 -b Allow broadcast -C Send CRLF as line-ending -D Enable the debug socket option -d Detach from stdin -F Pass socket fd -h This help text -I length TCP receive buffer length -i interval Delay interval for lines sent, ports scanned -k Keep inbound sockets open for multiple connects -l Listen mode, for inbound connects -M ttl Outgoing TTL / Hop Limit -m minttl Minimum incoming TTL / Hop Limit -N Shutdown the network socket after EOF on stdin -n Suppress name/port resolutions -O length TCP send buffer length -P proxyuser Username for proxy authentication -p port Specify local port for remote connects -q secs quit after EOF on stdin and delay of secs -r Randomize remote ports -S Enable the TCP MD5 signature option -s sourceaddr Local source address -T keyword TOS value -t Answer TELNET negotiation -U Use UNIX domain socket -u UDP mode -V rtable Specify alternate routing table -v Verbose -W recvlimit Terminate after receiving a number of packets -w timeout 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 DCCP mode -z Zero-I/O mode [used for scanning]
常用，测试UDP端口是否开通
nc -vzu 172.18.1.1 161