Nginx Block And Deny IP Address OR Network Subnets

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How do I block or deny access based on the host name or IP address of the client visiting website under nginx web server?

Nginx comes with a simple module called ngx_http_access_module to allow or deny access to IP address. The syntax is as follows:

deny IP;
deny subnet;
allow IP;
allow subnet;
# block all ips
deny    all;
# allow all ips 
allow    all;

Note rules are checked in the order of their record to the first match.

How Do I Configure Nginx To Block IPs?

Edit nginx.conf file, enter (note my nginx path is set to /usr/local/nginx/, replace this according to your setup):

cd /usr/local/nginx/conf/
vi nginx.conf

Add the following line in http section:

## Block spammers and other unwanted visitors  ##
 include blockips.conf;

vi nginx.conf

Save and close the file. Finally, create blockips.conf in /usr/local/nginx/conf/, enter:

vi blockips.conf

Append / add entries as follows:

deny 1.2.3.4;
deny 91.212.45.0/24;
deny 91.212.65.0/24;

Save and close the file. Test the config file, enter:

/usr/local/nginx/sbin/nginx -t

Sample outputs:

the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
configuration file /usr/local/nginx/conf/nginx.conf test is successful

Reload the new config, enter:

/usr/local/nginx/sbin/nginx -s reload

How Do I Deny All and Allow Only Intranet/LAN IPs?

Edit config file as follows:

location / {
  # block one workstation
  deny    192.168.1.1;
  # allow anyone in 192.168.1.0/24
  allow   192.168.1.0/24;
  # drop rest of the world 
  deny    all;
}

Granted access to network 192.168.1.0/24 with the exception of the address 192.168.1.1.

How Do I Customize HTTP 403 Forbidden Error Messages?

Create a file called error403.html in default document root, enter:

cd /usr/local/nginx/html
vi error403.htm
<html> 
<head>
<title>Error 403 - IP Address Blocked</title>
</head> 
<body> Your IP Address is blocked. If you this an error, please contact webmaster with your IP at webmaster@example.com </body> </html>

If SSI enabled, you can display the client IP easily from the html page itself:

Your IP Address is <!--#echo var="REMOTE_ADDR" --> blocked.

Save and close the file. Edit your nginx.conf file, enter:

vi nginx.conf
# redirect server error pages to the static page
 error_page   403  /error403.html;
 location = /error403.html {
         root   html;
 }

Save and close the file. Reload nginx, enter:

/usr/local/nginx/sbin/nginx -s reload

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