问题：mac系统nginx无法监听80端口
原因：mac系统不能监听小于1024的端口
解决问题
一、设置端口转发
1. 创建idea.tomcat.forwarding文件
运行命令：sudo vim /etc/pf.anchors/idea.tomcat.forwarding
在idea.tomcat.forwarding添加以下命令
rdr pass on lo0 inet proto tcp from any to 127.0.0.1 port 80 -> 127.0.0.1 port 8080
//这个配置是说80端口转发到8080 【比如：本地启动服务8080端口，浏览器访问：http://127.0.0.1】
2. 创建pf-tomcat.conf文件
运行命令：sudo vim /etc/pf-tomcat.conf
在pf-tomcat.conf添加以下命令
rdr-anchor "forwarding"
load anchor "forwarding" from "/etc/pf.anchors/idea.tomcat.forwarding"
3. 启动端口转发功能
运行命令：sudo pfctl -ef /etc/pf-tomcat.conf
pfctl: Use of -f option, could result in flushing of rules
present in the main ruleset added by the system at startup.
See /etc/pf.conf for further details.
No ALTQ support in kernel
ALTQ related functions disabled
pfctl: pf already enabled
//出现以上代码表示转发端口启动成功
