The warning "low address bits are meaningless" occurs when you specify a CIDR notation where the network portion of the IP address contains bits that would be ignored by the subnet mask. In your case, 192.168.0.1/24 is problematic because the last octet (.1) is part of the host portion in a /24 subnet.

For proper IP-based access control in Nginx, you should specify just the network portion in your allow directive:

location ~ /ghost/signin {
    allow 192.168.0.0/24;
    deny all;
}

The original configuration used 192.168.0.1/24, which Nginx interprets as:

• Network address: 192.168.0.0
• Subnet mask: 255.255.255.0
• Host portion: 0.0.0.1

Since a /24 subnet mask means the first 24 bits (three octets) define the network, the final octet is the host portion. Specifying .1 in the host portion is ignored, making it meaningless.

To verify your access restrictions are working, try these curl commands:

# From an external IP (should be denied)
curl -I http://yourdomain.com/ghost/signin

# From your intranet (should be allowed)
curl -I http://yourdomain.com/ghost/signin

For more complex scenarios, you might want to:

# Allow multiple subnets
location ~ /ghost/signin {
    allow 192.168.0.0/24;
    allow 10.0.0.0/8;
    deny all;
}

# Or combine with other restrictions
location ~ /ghost/signin {
    allow 192.168.0.0/24;
    deny all;
    auth_basic "Restricted";
    auth_basic_user_file /etc/nginx/.htpasswd;
}

Always test your configuration before reloading Nginx:

sudo nginx -t
sudo systemctl reload nginx

Check the error logs if you're still having issues:

tail -f /var/log/nginx/error.log

While IP-based restrictions are useful for intranet access, consider additional security measures:

• Use HTTPS for all sensitive pages
• Implement proper authentication
• Consider rate limiting
• Keep Nginx updated

When working with Nginx's access control directives, you might encounter the warning "low address bits are meaningless." This occurs when specifying IP ranges in CIDR notation where the network portion of the address doesn't align with the subnet mask.

In your case, 192.168.0.1/24 is problematic because:

• The /24 mask means only the first three octets (192.168.0) are significant
• The ".1" in the last octet is ignored (thus "meaningless")
• Nginx expects the host portion to be zero in CIDR notation

For a /24 subnet, you should specify the network address (with 0 in the host portion):

location ~ /ghost/signin {
    allow 192.168.0.0/24;
    deny all;
}

The original configuration 192.168.0.1/24 is technically incorrect because:

1. Nginx interprets it as 192.168.0.0/24 anyway
2. Some Nginx versions might reject it completely
3. The warning indicates the configuration isn't being applied as intended

Here's a proper implementation for intranet access restriction:

server {
    # ... other server config ...
    
    location ~ ^/ghost/signin {
        allow 192.168.0.0/24;
        allow 127.0.0.1;
        deny all;
        
        # Your existing location configuration
        proxy_pass http://ghost_backend;
        # ... other directives ...
    }
}

When working with Nginx access controls:

• Always use the network address (ending in .0) for CIDR ranges
• Test your configuration with nginx -t before reloading
• For multiple subnets, list them separately:

  allow 192.168.1.0/24;
  allow 10.0.0.0/8;

• Remember that allow/deny directives are evaluated in order

If you're still having problems:

1. Check your client IP with curl ifconfig.me or local network tools
2. Add logging to your location block:

   access_log /var/log/nginx/ghost_access.log;

3. Verify your network infrastructure isn't NATing or changing the source IP