Nginx Proxying Long URL Addresses

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If you are using Nginx as reverse proxy, you may encounter some of the following behaviors

192.168.1.1 - - [09/May/2019:10:26:58 +0300] "-" 000 0 "-" "-" "-"
192.168.1.1 - - [09/May/2019:10:09:55 +0300] "-" 000 0 "-" "-" "-"

I was observing such behavior when trying to access some very long URL/URI’s through nginx proxying.

The bad thing is that Nginx doesn’t log anything usefull, that could be of help for locating the problem.

Most of the times with long url’s, the problem is inside your buffer configuration settings.

Here is how to get rid of these messages and fix the problem.

For http only connections, you should add the following directives to your http {} or server{} config sections:

large_client_header_buffers 4 128k;

If your addresses are bigger than 128K, you should modify it accordingly.

If you are using HTTPS with HTTP2 module, there are some additional settings you need to add:

large_client_header_buffers 4 128k;

http2_max_header_size 128k; 
http2_max_field_size  128k;

Again the directives should be modified based on the sizes you are working with, but most of the times 128k would be sufficient.