How to fix error Nginx “502 Bad Gateway”

Today I will post article “The fix error 502 Bad Gateway for Nginx”.This error can be called “WordPress Xmlrpc vulnerability”. This could be that your server is compromised. you are getting a lot of requests to your xmlrpc.php file. and its keeping your server out of resources.

You check the log and if it appears the following error:

2015/07/22 16:56:16 21550#0: *24455 upstream sent unexpected FastCGI record: 3 while reading response header from upstream, client: xxxx.xxx.xx.xx, server: xxx, request: “POST /xmlrpc.php HTTP/1.0″, upstream: “xxx.xxx.xx.xx., host: “xxx.xxx.xxx.xxx”

What to do?

1. After doing a simple Google search I solved the problem by adding two lines to Nginx configuration file/etc/nginx/nginx.conf :

If you use centminmod url see here: /usr/local/nginx/nginx.conf

http {
    ...
    fastcgi_buffers 8 16k;
    fastcgi_buffer_size 32k;
    ...
}

2. Disable plugin Example: iThemes Security,use rename the folder better-wp-security

3. Default nginx config file will be located at /etc/nginx/sites-available/default, you can add the below lines in server context.
location ^~ /xmlrpc.php {
deny all;
}

Centminmod: Go to /usr/local/nginx/conf/conf.d/domain.com.conf

Add row:  location ^~ /xmlrpc.php { deny all;}

at 

server {

... }

Now restart nginx using below command.

service nginx restart

Good luck!