在很多生产环境中会需要测试端口是否连通，在很多时候生产环境中未安装 telnet 等一系列命令，这就需要我们学习更多的几种测试端口的方式。以下是对常用的几种方式进行整理。
- curl
curl -v ip:port
# 成功
# About to connect() to xxx port xx(#0)
# Trying 192.168.3.234...
# Connected to xxx (xxx) port xxx (#0)
- ssh
ssh -v -p port ip
#成功
#OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017
#debug1: Reading configuration data /etc/ssh/ssh_config
#debug1: /etc/ssh/ssh_config line 58: Applying options for *
#debug1: Connecting to x.x.x.x [x.x.x.x] port xx.
#debug1: Connection established.
- telnet
telnet ip port
# 成功
#Trying x.x.x.x...
#Connected to x.x.x.x.
#Escape character is '^]'.
- wget
wget ip:port
#成功
# 正在连接 x.x.x.x:xx... 已连接。
# 已发出 HTTP 请求，正在等待回应... 200 OK
- nc
#tcp
nc -vz ip port
#udp
nc -uz ip port
#成功
#Ncat: Version 7.50 ( https://nmap.org/ncat )
#Ncat: Connected to x.x.x.x:xx.
#Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
