正向代理是一个位于客户端和原始服务器(origin server)之间的服务器，为了从原始服务器取得内容，客户端向代理发送一个请求并指定目标(原始服务器)，然后代理向原始服务器转交请求并将获得的内容返回给客户端。客户端必须要进行一些特别的设置才能使用正向代理。
正向代理的典型用途是为在防火墙内的局域网客户端提供访问Internet的途径。
反向代理正好相反，对于客户端而言它就像是原始服务器，并且客户端不需要进行任何特别的设置。客户端向反向代理的命名空间(name-space)中的内容发送普通请求，接着反向代理将判断向何处(原始服务器)转交请求，并将获得的内容返回给客户端，就像这些内容原本就是它自己的一样。
反向代理的典型用途是将防火墙后面的服务器提供给Internet用户访问。反向代理还可以为后端的多台服务器提供负载平衡，或为后端较慢的服务器提供缓冲服务。另外，还可以启用高级URL策略和管理技术，从而使处于不同web服务器系统的web页面同时存在于同一个URL空间下。
一、环境准备：
# dmidecode|grep "System Information" -A9|egrep "Manufacturer|Product"
Manufacturer: Dell Inc.
Product Name: PowerEdge R630
# uname -a
Linux linux-node2 3.10.0-693.21.1.el7.x86_64 #1 SMP Wed Mar 7 19:03:37 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
关闭firewalld,selinux
#yum install -y prce-devel openssl-devel (安装依赖包）
#yum install -y gcc glibc gcc-c++ make screen tree lrzsz wget curl vim
Configuration summary(可单独编译)
+ using system PCRE library
+ using system OpenSSL library
+ using system zlib library
#useradd -s /sbin/nologin -M www
#cd /usr/local/src
#wget http://nginx.org/download/nginx-1.14.0.tar.gz
#tar -zxf nginx-1.14.0.tar.gz
#cd /nginx-1.14.0
编译安装
#mkdir /usr/local/nginx-1.14.0
./configure --prefix=/usr/local/nginx-1.14.0 --user=www --group=www --with-http_ssl_module --with-http_stub_status_module --with-file-aio
#make && make install
#ln -s /usr/local/nginx-1.14.0 /usr/local/nginx
检查配置语法，成功如下
#/usr/local/nginx-1.14.0/sbin/nginx -t
＃/usr/local/nginx-1.14.0/sbin/nginx -s reload(相当于graceful)
nginx: the configuration file /usr/local/nginx-1.14.0/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx-1.14.0/conf/nginx.conf test is successful
如出现以下报错
[root@ms02 nginx-1.14.0]# /usr/local/nginx-1.14.0/sbin/nginx -t
nginx: the configuration file /usr/local/nginx-1.14.0/conf/nginx.conf syntax is ok
nginx: [emerg] getpwnam("www") failed
nginx: configuration file /usr/local/nginx-1.14.0/conf/nginx.conf test failed
处理方法一：
解决方案一
在nginx.conf中 把user nobody的注释去掉既可
解决方案二
错误的原因是没有创建www这个用户，应该在服务器系统中添加www用户组和用户www，如下命令：
详细配置：
[root@ms01 conf]# vi /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.119.110 ms01.unicom.com loadblance.unicom.com
192.168.119.111 ms02.unicom.com
#[root@ms01 conf]# cat nginx.conf
#user nobody;
worker_processes 1;
#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;
#pid logs/nginx.pid;
events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
#log_format main '$remote_addr - $remote_user [$time_local] "$request" '
# '$status $body_bytes_sent "$http_referer" '
# '"$http_user_agent" "$http_x_forwarded_for"';
#access_log logs/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
#gzip on;
upstream backend {
server 192.168.119.110:8080 weight=1;
server 192.168.119.111:8080 weight=2;
#server unix:/tmp/backend3;
#server backup1.example.com:8080 backup;
#server backup2.example.com:8080 backup;
}
server {
listen 80;
server_name ms01.unicom.com;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root html;
index index.html index.htm;
proxy_pass http://backend;
}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ .php$ {
# proxy_pass http://127.0.0.1;
#}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
#location ~ .php$ {
# root html;
# fastcgi_pass 127.0.0.1:9000;
# fastcgi_index index.php;
# fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;
# include fastcgi_params;
#}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
#location ~ /.ht {
# deny all;
#}
}
# another virtual host using mix of IP-, name-, and port-based configuration
#
#server {
# listen 8000;
# listen somename:8080;
# server_name somename alias another.alias;
# location / {
# root html;
# index index.html index.htm;
# }
#}
# HTTPS server
#
#server {
# listen 443 ssl;
# server_name localhost;
# ssl_certificate cert.pem;
# ssl_certificate_key cert.key;
# ssl_session_cache shared:SSL:1m;
# ssl_session_timeout 5m;
# ssl_ciphers HIGH:!aNULL:!MD5;
# ssl_prefer_server_ciphers on;
# location / {
# root html;
# index index.html index.htm;
# }
#}
}
测试机器HOSTS文件添加上服务器的HOST
192.168.119.110 ms01.unicom.com loadbalance.unicom.com
192.168.119.111 ms02.unicom.com