Nginx Quick Reference

`My notes about Nginx...`

_{Created by
trimstray and

contributors}

Introduction

Before using the Nginx please read Beginner’s Guide.

Nginx (/ˌɛndʒɪnˈɛks/ EN-jin-EKS) is an HTTP and reverse proxy server, a mail proxy server, and a generic TCP/UDP proxy server, originally written by Igor Sysoev. For a long time, it has been running on many heavily loaded Russian sites including Yandex, Mail.Ru, VK, and Rambler.

To increase your knowledge, read Nginx Documentation.

General disclaimer

This is not an official handbook. Many of these rules refer to external resources. It is rather a quick collection of some rules used by me in production environments (not only).

Before you start remember about the two most important things:

Do not follow guides just to get 100% of something. Think about what you actually do at your server!

These guidelines provides recommendations for very restrictive setup.

Contributing

If you find something which doesn't make sense, or one of these doesn't seem right, or something seems really stupid; please make a pull request or please add valid and well-reasoned opinions about your changes or comments.

Before add pull request please see this.

SSL Report: blkcipher.info

Many of these recipes have been applied to the configuration of my private website. I finally got all 100%'s on my scores:

An example configuration is in this chapter.

Printable high-res hardening checklist

Hardening checklist based on these recipes (@ssllabs A+ 100%) - High-Res 5000x8200.

For *.xcf and *.pdf formats please see this directory.

External Resources

Performance & Hardening

Config generators

:black_small_square: Nginx config generator on steroids

Static analyzers

:black_small_square: Nginx static analyzer

Log analyzers

  :black_small_square: GoAccess
  :black_small_square: Graylog
  :black_small_square: Logstash

Performance analyzers

:black_small_square: ngxtop

Benchmarking tools

  :black_small_square: siege
  :black_small_square: wrk
  :black_small_square: bombardier
  :black_small_square: gobench

Online tools

Other stuff

:black_small_square: BBC Digital Media Distribution: How we improved throughput by 4x
:black_small_square: Web cache server performance benchmark: nuster vs nginx vs varnish vs squid

Helpers

Shell aliases

alias ng.test='nginx -t -c /etc/nginx/nginx.conf'
alias ng.stop='ng.test && systemctl stop nginx'
alias ng.reload='ng.test && systemctl reload nginx'
alias ng.restart='ng.test && systemctl restart nginx'
# or
alias ng.restart='ng.test && kill -HUP `cat /var/run/nginx.pid`'

Debugging

See the top 5 IP addresses in a web server log

cut -d ' ' -f1 /path/to/logfile | sort | uniq -c | sort -nr | head -5 | nl

Analyse web server log and show only 2xx http codes

tail -n 100 -f /path/to/logfile | grep "HTTP/[1-2].[0-1]\" [2]"

Analyse web server log and show only 5xx http codes

tail -n 100 -f /path/to/logfile | grep "HTTP/[1-2].[0-1]\" [5]"

Get range of dates in a web server log

# 1)
awk '/'$(date -d "1 hours ago" "+%d\\/%b\\/%Y:%H:%M")'/,/'$(date "+%d\\/%b\\/%Y:%H:%M")'/ { print $0 }' /path/to/logfile

# 2)
awk '/05\/Feb\/2019:09:2.*/,/05\/Feb\/2019:09:5.*/' /path/to/logfile

Get line rates from web server log

tail -F /path/to/logfile | pv -N RAW -lc 1>/dev/null

Trace network traffic for all Nginx processes

strace -e trace=network -p `pidof nginx | sed -e 's/ /,/g'`

List all files accessed by a Nginx

strace -ff -e trace=file nginx 2>&1 | perl -ne 's/^[^"]+"(([^\\"]|\\[\\"nt])*)".*/$1/ && print'

Base rules

🔰 Organising Nginx configuration

Rationale

When your configuration grow, the need for organising your code will also grow. Well organised code is:

easier to understand

easier to maintain

easier to work with

Use include directive to attach your Nginx specific code to global config, contexts and other.

Example

# Store this configuration in e.g. https-ssl-common.conf
listen 10.240.20.2:443 ssl;

root /etc/nginx/error-pages/other;

ssl_certificate /etc/nginx/domain.com/certs/nginx_domain.com_bundle.crt;
ssl_certificate_key /etc/nginx/domain.com/certs/domain.com.key;

# And include this file in server section:
server {

  include /etc/nginx/domain.com/commons/https-ssl-common.conf;

  server_name domain.com www.domain.com;

  ...

External resources

Organize your data and code

🔰 Separate listen directives for 80 and 443

Rationale

...

Example

# For http:
server {

  listen 10.240.20.2:80;

  ...

}

# For https:
server {

  listen 10.240.20.2:443 ssl;

  ...

}

External resources

Understanding the Nginx Configuration File Structure and Configuration Contexts

🔰 Prevent processing requests with undefined server names

Rationale

Nginx should prevent processing requests with undefined server names - also traffic on IP address. It also protects against configuration errors and don't pass traffic to incorrect backends. The problem is easily solved by creating a default catch all server config.

If none of the listen directives have the default_server parameter then the first server with the address:port pair will be the default server for this pair.

If someone makes a request using an IP address instead of a server name, the Host request header field will contain the IP address and the request can be handled using the IP address as the server name.

I think the best solution is return 444; for default server name because this will close the connection and log it internally, for any domain that isn't defined in Nginx.

Example

# Place it at the beginning of the configuration file to prevent mistakes.
server {

  # Add default_server to your listen directive in the server that you want to act as the default.
  listen 10.240.20.2:443 default_server ssl;

  # We catch invalid domain names, requests without the "Host" header and all others (also due to the above setting).
  server_name _ "" default_server;

  ...

  return 444;

  # We can also serve:
  # location / {

    # static file (error page):
    # root /etc/nginx/error-pages/404;
    # or redirect:
    # return 301 https://badssl.com;

    # return 444;

  # }

}

server {

  listen 10.240.20.2:443 ssl;

  server_name domain.com;

  ...

}

server {

  listen 10.240.20.2:443 ssl;

  server_name domain.org;

  ...

}

External resources

🔰 Use only one SSL config for specific listen directive

Rationale

For sharing a single IP address between several HTTPS servers you should use one SSL config (e.g. protocols, ciphers, curves) because changes will affect only the default server.

Remember that regardless of SSL parameters, you are able to use multiple SSL certificates.

If you want to set up different SSL configurations for the same IP address then it will fail. It's important because SSL configuration is presented for default server - if none of the listen directives have the default_server parameter then the first server in your configuration. So you should use only one SSL setup with several names on the same IP address.

Example

# Store this configuration in e.g. https.conf
listen 192.168.252.10:443 default_server ssl http2;

ssl_protocols TLSv1.2;
ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384";

ssl_prefer_server_ciphers on;

ssl_ecdh_curve secp521r1:secp384r1;

...

# Include this file to the server context (attach domain-a.com for specific listen directive)
server {

  include /etc/nginx/https.conf;

  server_name domain-a.com;

  ...

}

# Include this file to the server context (attach domain-b.com for specific listen directive)
server {

  include /etc/nginx/https.conf;

  server_name domain-b.com;

  ...

}

External resources

Nginx one ip and multiple ssl certificates

🔰 Force all connections over TLS

Rationale

You should always use HTTPS instead of HTTP to protect your website, even if it doesn’t handle sensitive communications.

Example

server {

  listen 10.240.20.2:80;

  server_name domain.com;

  return 301 https://$host$request_uri;

}

server {

  listen 10.240.20.2:443 ssl;

  server_name domain.com;

  ...

}

External resources

Should we force user to HTTPS on website?

🔰 Use geo/map modules instead allow/deny

Rationale

Creates variables with values depending on the client IP address. Use map or geo modules (one of them) to prevent users abusing your servers.

Example

# Map module:
map $remote_addr $globals_internal_map_acl {

  # Status code:
  #  - 0 = false
  #  - 1 = true
  default 0;

  ### INTERNAL ###
  10.255.10.0/24 1;
  10.255.20.0/24 1;
  10.255.30.0/24 1;
  192.168.0.0/16 1;

}

# Geo module:
geo $globals_internal_geo_acl {

  # Status code:
  #  - 0 = false
  #  - 1 = true
  default 0;

  ### INTERNAL ###
  10.255.10.0/24 1;
  10.255.20.0/24 1;
  10.255.30.0/24 1;
  192.168.0.0/16 1;

}

External resources

Nginx Basic Configuration (Geo Ban)

🔰 Map all the things...

Rationale

Manage a large number of redirects with Nginx maps.

Map module provides a more elegant solution for clearly parsing a big list of regexes, e.g. User-Agents.

Example

map $http_user_agent $device_redirect {

  default "desktop";

  ~(?i)ip(hone|od) "mobile";
  ~(?i)android.*(mobile|mini) "mobile";
  ~Mobile.+Firefox "mobile";
  ~^HTC "mobile";
  ~Fennec "mobile";
  ~IEMobile "mobile";
  ~BB10 "mobile";
  ~SymbianOS.*AppleWebKit "mobile";
  ~Opera\sMobi "mobile";

}

if ($device_redirect = "mobile") {

  return 301 https://m.domain.com$request_uri;

}

External resources

Cool Nginx feature of the week

🔰 Drop the same root inside location block

Rationale

If you add a root to every location block then a location block that isn’t matched will have no root. Set global root inside server directive.

Example

server {

  server_name domain.com;

  root /var/www/domain.com/public;

  location / {

    ...

  }

  location /api {

    ...

  }

  location /static {

    root /var/www/domain.com/static;

    ...

  }

}

External resources

Nginx Pitfalls: Root inside location block

🔰 Use debug mode for debugging

Rationale

There's probably more detail than you want, but that can sometimes be a lifesaver (but log file growing rapidly on a very high-traffic sites).

Example

rewrite_log on;
error_log /var/log/nginx/error-debug.log debug;

External resources

A debugging log

🔰 Use custom log formats

Rationale

Anything you can access as a variable in Nginx config, you can log, including non-standard http headers, etc. so it's a simple way to create your own log format for specific situations.

This is extremely helpful for debugging specific location directives.

Example

# Default main log format from nginx repository:
log_format main
                '$remote_addr - $remote_user [$time_local] "$request" '
                '$status $body_bytes_sent "$http_referer" '
                '"$http_user_agent" "$http_x_forwarded_for"';

# Extended main log format:
log_format main-level-0
                '$remote_addr - $remote_user [$time_local] '
                '"$request_method $scheme://$host$request_uri '
                '$server_protocol" $status $body_bytes_sent '
                '"$http_referer" "$http_user_agent" '
                '$request_time';

# Debug log formats:
log_format debug-level-0
                '$remote_addr - $remote_user [$time_local] '
                '"$request_method $scheme://$host$request_uri '
                '$server_protocol" $status $body_bytes_sent '
                '$request_id $pid $msec $request_time '
                '$upstream_connect_time $upstream_header_time '
                '$upstream_response_time "$request_filename" '
                '$request_completion';

log_format debug-level-1
                '$remote_addr - $remote_user [$time_local] '
                '"$request_method $scheme://$host$request_uri '
                '$server_protocol" $status $body_bytes_sent '
                '$request_id $pid $msec $request_time '
                '$upstream_connect_time $upstream_header_time '
                '$upstream_response_time "$request_filename" $request_length '
                '$request_completion $connection $connection_requests';

log_format debug-level-2
                '$remote_addr - $remote_user [$time_local] '
                '"$request_method $scheme://$host$request_uri '
                '$server_protocol" $status $body_bytes_sent '
                '$request_id $pid $msec $request_time '
                '$upstream_connect_time $upstream_header_time '
                '$upstream_response_time "$request_filename" $request_length '
                '$request_completion $connection $connection_requests '
                '$server_addr $server_port $remote_addr $remote_port';

External resources

Performance

🔰 Adjust worker processes

Rationale

The worker_processes directive is the sturdy spine of life for Nginx. This directive is responsible for letting our virtual server know many workers to spawn once it has become bound to the proper IP and port(s).

Official Nginx documentation say:

When one is in doubt, setting it to the number of available CPU cores would be a good start (the value "auto" will try to autodetect it).

I think for high load proxy servers (also standalone servers) good value is ALL_CORES - 1 (please test it before used).

Example

# VCPU = 4 , expr $(nproc --all) - 1
worker_processes 3;

External resources

Nginx Core Module - worker_processes

🔰 Use HTTP/2

Rationale

HTTP/2 will make our applications faster, simpler, and more robust.

The primary goals for HTTP/2 are to reduce latency by enabling full request and response multiplexing, minimize protocol overhead via efficient compression of HTTP header fields, and add support for request prioritization and server push.

HTTP/2 is backwards-compatible with HTTP/1.1, so it would be possible to ignore it completely and everything will continue to work as before.

Example

# For https:
server {

  listen 10.240.20.2:443 ssl http2;

  ...

External resources

🔰 Maintaining SSL Sessions

Rationale

This improves performance from the clients’ perspective, because it eliminates the need for a new (and time-consuming) SSL handshake to be conducted each time a request is made.

Most servers do not purge sessions or ticket keys, thus increasing the risk that a server compromise would leak data from previous (and future) connections.

Example

ssl_session_cache shared:SSL:10m;
ssl_session_timeout 24h;
ssl_session_tickets off;
ssl_buffer_size 1400;

External resources

🔰 Use exact names where possible

Rationale

Exact names, wildcard names starting with an asterisk, and wildcard names ending with an asterisk are stored in three hash tables bound to the listen ports.

The exact names hash table is searched first. If a name is not found, the hash table with wildcard names starting with an asterisk is searched. If the name is not found there, the hash table with wildcard names ending with an asterisk is searched. Searching wildcard names hash table is slower than searching exact names hash table because names are searched by domain parts.

Regular expressions are tested sequentially and therefore are the slowest method and are non-scalable. For these reasons, it is better to use exact names where possible.

Example

# It is more efficient to define them explicitly:
server {

    listen       80;

    server_name  example.org  www.example.org  *.example.org;

    ...

}

# than to use the simplified form:
server {

    listen       80;

    server_name  .example.org;

    ...

}

External resources

Server names

Hardening

🔰 Run as an unprivileged user

Rationale

There is no real difference in security just by changing the process owner name. On the other hand in security, the principle of least privilege states that an entity should be given no more permission than necessary to accomplish its goals within a given system. This way only master process runs as root.

Example

# Edit nginx.conf:
user www-data;

# Set owner and group for root (app, default) directory:
chown -R www-data:www-data /var/www/domain.com

External resources

Why does nginx starts process as root?

🔰 Disable unnecessary modules

Rationale

It is recommended to disable any modules which are not required as this will minimize the risk of any potential attacks by limiting the operations allowed by the web server.

Example

# During installation:
./configure --without-http_autoindex_module

# Comment modules in the configuration file e.g. modules.conf:
# load_module                 /usr/share/nginx/modules/ndk_http_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_auth_pam_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_cache_purge_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_dav_ext_module.so;
load_module                   /usr/share/nginx/modules/ngx_http_echo_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_fancyindex_module.so;
load_module                   /usr/share/nginx/modules/ngx_http_geoip_module.so;
load_module                   /usr/share/nginx/modules/ngx_http_headers_more_filter_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_image_filter_module.so;
# load_module                 /usr/share/nginx/modules/ngx_http_lua_module.so;
load_module                   /usr/share/nginx/modules/ngx_http_perl_module.so;
# load_module                 /usr/share/nginx/modules/ngx_mail_module.so;
# load_module                 /usr/share/nginx/modules/ngx_nchan_module.so;
# load_module                 /usr/share/nginx/modules/ngx_stream_module.so;

External resources

nginx-modules

🔰 Protect sensitive resources

Rationale

Hidden directories and files should never be web accessible.

Example

if ($request_uri ~ "/\.git") {

  return 403;

}

# or
location ~ /\.git {

  deny all;

}

# or
location ~* ^.*(\.(?:git|svn|htaccess))$ {

  return 403;

}

# or all . directories/files excepted .well-known
location ~ /\.(?!well-known\/) {

  deny all;

}

External resources

Hidden directories and files as a source of sensitive information about web application

🔰 Hide Nginx version number

Rationale

Disclosing the version of Nginx running can be undesirable, particularly in environments sensitive to information disclosure.

The "Official Apache Documentation (Apache Core Features)" say:

Setting ServerTokens to less than minimal is not recommended because it makes it more difficult to debug interoperational problems. Also note that disabling the Server: header does nothing at all to make your server more secure. The idea of "security through obscurity" is a myth and leads to a false sense of safety.

Example

server_tokens off;

External resources

🔰 Hide Nginx server signature

Rationale

In my opinion there is no real reason or need to show this much information about your server. It is easy to look up particular vulnerabilities once you know the version number.

You should compile Nginx from sources with ngx_headers_more to used more_set_headers directive.

Example

more_set_headers "Server: Unknown";

External resources

🔰 Hide upstream proxy headers

Rationale

When Nginx is used to proxy requests to an upstream server (such as a PHP-FPM instance), it can be beneficial to hide certain headers sent in the upstream response (e.g. the version of PHP running).

Example

proxy_hide_header X-Powered-By;
proxy_hide_header X-AspNetMvc-Version;
proxy_hide_header X-AspNet-Version;
proxy_hide_header X-Drupal-Cache;

External resources

Remove insecure http headers

🔰 Use only 4096-bit private keys

Rationale

Advisories recommend 2048 for now. Security experts are projecting that 2048 bits will be sufficient for commercial use until around the year 2030.

Generally there is no compelling reason to choose 4096 bit keys over 2048 provided you use sane expiration intervals.

If you want to get A+ with 100%s on SSL Lab you should definitely use 4096 bit private key.

I always generate 4096 bit keys for low busy sites since the downside is minimal (slightly lower performance) and security is slightly higher (although not as high as one would like).

Use of alternative solution: ECC Certificate Signing Request (CSR).

The "SSL/TLS Deployment Best Practices" book say:

The cryptographic handshake, which is used to establish secure connections, is an operation whose cost is highly influenced by private key size. Using a key that is too short is insecure, but using a key that is too long will result in “too much” security and slow operation. For most web sites, using RSA keys stronger than 2048 bits and ECDSA keys stronger than 256 bits is a waste of CPU power and might impair user experience. Similarly, there is little benefit to increasing the strength of the ephemeral key exchange beyond 2048 bits for DHE and 256 bits for ECDHE.

Konstantin Ryabitsev (Reddit):

Generally speaking, if we ever find ourselves in a world where 2048-bit keys are no longer good enough, it won't be because of improvements in brute-force capabilities of current computers, but because RSA will be made obsolete as a technology due to revolutionary computing advances. If that ever happens, 3072 or 4096 bits won't make much of a difference anyway. This is why anything above 2048 bits is generally regarded as a sort of feel-good hedging theatre.

Example

### Example (RSA):
( _fd="domain.com.key" ; _len="4096" ; openssl genrsa -out ${_fd} ${_len} )

# Let's Encrypt:
certbot certonly -d domain.com -d www.domain.com --rsa-key-size 4096

### Example (ECC):
# _curve: prime256v1, secp521r1, secp384r1
( _fd="domain.com.key" ; _fd_csr="domain.com.csr" ; _curve="prime256v1" ; \
openssl ecparam -out ${_fd} -name ${_curve} -genkey ; openssl req -new -key ${_fd} -out ${_fd_csr} -sha256 )

# Let's Encrypt (from above):
certbot --csr ${_fd_csr} -[other-args]

For x25519:

( _fd="private.key" ; _curve="x25519" ; \
openssl genpkey -algorithm ${_curve} -out ${_fd} )

_{ssllabs score: 100}

( _fd="domain.com.key" ; _len="2048" ; openssl genrsa -out ${_fd} ${_len} )

# Let's Encrypt:
certbot certonly -d domain.com -d www.domain.com

_{ssllabs score: 90}

External resources

So you're making an RSA key for an HTTPS certificate. What key size do you use?

🔰 Keep only TLS 1.2 (+ TLS 1.3)

Rationale

It is recommended to run TLS 1.1/1.2 and fully disable SSLv2, SSLv3 and TLS 1.0 that have protocol weaknesses.

TLS 1.1 and 1.2 are both without security issues - but only v1.2 provides modern cryptographic algorithms. TLS 1.0 and TLS 1.1 protocols will be removed from browsers at the beginning of 2020.

Example

ssl_protocols TLSv1.2;

# For TLS 1.3
ssl_protocols TLSv1.2 TLSv1.3;

_{ssllabs score: 100}

ssl_protocols TLSv1.2 TLSv1.1;

_{ssllabs score: 95}

External resources

🔰 Use only strong ciphers

Rationale

This parameter changes quite often, the recommended configuration for today may be out of date tomorrow.

For more security use only strong and not vulnerable ciphersuite (but if you use HTTP/2 you can get Server sent fatal alert: handshake_failure error).

Place ECDHE and DHE suites at the top of your list. The order is important; because ECDHE suites are faster, you want to use them whenever clients supports them.

For backward compatibility software components you should use less restrictive ciphers.

You should definitely disable weak ciphers like those with DSS, DSA, DES/3DES, RC4, MD5, SHA1, null, anon in the name.

Example

ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384";

_{ssllabs score: 100}

# 1)
ssl_ciphers "ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA:ECDHE-ECDSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256";

# 2)
ssl_ciphers "ECDHE-ECDSA-CHACHA20-POLY1305:ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:!AES256-GCM-SHA256:!AES256-GCM-SHA128:!aNULL:!MD5";

_{ssllabs score: 90}

Ciphersuite for TLS 1.3:

ssl_ciphers "TLS13-CHACHA20-POLY1305-SHA256:TLS13-AES-256-GCM-SHA384:TLS13-AES-128-GCM-SHA256";

External resources

🔰 Use more secure ECDH Curve

Rationale

For a SSL server certificate, an "elliptic curve" certificate will be used only with digital signatures (ECDSA algorithm).

x25519 is a more secure but slightly less compatible option. To maximise interoperability with existing browsers and servers, stick to P-256 prime256v1 and P-384 secp384r1 curves.

NSA Suite B says that NSA uses curves P-256 and P-384 (in OpenSSL, they are designated as, respectively, prime256v1 and secp384r1). There is nothing wrong with P-521, except that it is, in practice, useless. Arguably, P-384 is also useless, because the more efficient P-256 curve already provides security that cannot be broken through accumulation of computing power.

Use P-256 to minimize trouble. If you feel that your manhood is threatened by using a 256-bit curve where a 384-bit curve is available, then use P-384: it will increases your computational and network costs.

If you do not set ssh_ecdh_curve, then the Nginx will use its default settings, e.g. Chrome will prefer x25519, but this is not recommended because you can not control the Nginx's default settings (seems to be P-256).

Explicitly set ssh_ecdh_curve X25519:prime256v1:secp521r1:secp384r1; decreases the Key Exchange SSL Labs rating.

Definitely do not use the secp112r1, secp112r2, secp128r1, secp128r2, secp160k1, secp160r1, secp160r2, secp192k1 curves. They have a too small size for security application according to NIST recommendation.

Example

ssl_ecdh_curve secp521r1:secp384r1;

_{ssllabs score: 100}

# Alternative (this one doesn’t affect compatibility, by the way; it’s just a question of the preferred order). This setup downgrade Key Exchange score:
ssl_ecdh_curve X25519:prime256v1:secp521r1:secp384r1;

External resources

🔰 Use strong Key Exchange

Rationale

The DH key is only used if DH ciphers are used. Modern clients prefer ECDHE instead and if your Nginx accepts this preference then the handshake will not use the DH param at all since it will not do a DHE key exchange but an ECDHE key exchange.

Most of the "modern" profiles from places like Mozilla's ssl config generator no longer recommend using this.

Default key size in OpenSSL is 1024 bits - it's vulnerable and breakable. For the best security configuration use your own 4096 bit DH Group or use known safe ones pre-defined DH groups (it's recommended) from mozilla.

Example

# To generate a DH key:
openssl dhparam -out /etc/nginx/ssl/dhparam_4096.pem 4096

# To produce "DSA-like" DH parameters:
openssl dhparam -dsaparam -out /etc/nginx/ssl/dhparam_4096.pem 4096

# To generate a ECDH key:
openssl ecparam -out /etc/nginx/ssl/ecparam.pem -name prime256v1

# Nginx configuration:
ssl_dhparam /etc/nginx/ssl/dhparams_4096.pem;

_{ssllabs score: 100}

External resources

🔰 Defend against the BEAST attack

Rationale

Enables server-side protection from BEAST attacks.

Example

ssl_prefer_server_ciphers on;

External resources

Is BEAST still a threat?

🔰 Disable HTTP compression (mitigation of CRIME/BREACH attacks)

Rationale

You should probably never use TLS compression. Some user agents (at least Chrome) will disable it anyways. Disabling SSL/TLS compression stops the attack very effectively.

Some attacks are possible because of gzip (HTTP compression not TLS compression) being enabled on SSL requests. In most cases, the best action is to simply disable gzip for SSL.

You shouldn't use HTTP compression on private responses when using TLS.

Compression can be (i think) okay to HTTP compress publicly available static content like css or js and HTML content with zero sensitive info (like an "About Us" page).

Example

gzip off;

External resources

🔰 HTTP Strict Transport Security

Rationale

The header indicates for how long a browser should unconditionally refuse to take part in unsecured HTTP connection for a specific domain.

Example

add_header Strict-Transport-Security "max-age=63072000; includeSubdomains" always;

_{ssllabs score: A+}

External resources

HTTP Strict Transport Security Cheat Sheet

🔰 Reduce XSS risks (Content-Security-Policy)

Rationale

CSP reduce the risk and impact of XSS attacks in modern browsers.

Example

# This policy allows images, scripts, AJAX, and CSS from the same origin, and does not allow any other resources to load.
add_header Content-Security-Policy "default-src 'none'; script-src 'self'; connect-src 'self'; img-src 'self'; style-src 'self';" always;

External resources

🔰 Control the behavior of the Referer header (Referrer-Policy)

Rationale

Determine what information is sent along with the requests.

Example

add_header Referrer-Policy "no-referrer";

External resources

A new security header: Referrer Policy

🔰 Provide clickjacking protection (X-Frame-Options)

Rationale

Helps to protect your visitors against clickjacking attacks. It is recommended that you use the x-frame-options header on pages which should not be allowed to render a page in a frame.

Example

add_header X-Frame-Options "SAMEORIGIN" always;

External resources

Clickjacking Defense Cheat Sheet

🔰 Prevent some categories of XSS attacks (X-XSS-Protection)

Rationale

Enable the cross-site scripting (XSS) filter built into modern web browsers.

Example

add_header X-XSS-Protection "1; mode=block" always;

External resources

X-XSS-Protection HTTP Header

🔰 Prevent Sniff Mimetype middleware (X-Content-Type-Options)

Rationale

It prevents the browser from doing MIME-type sniffing (prevents "mime" based attacks).

Example

add_header X-Content-Type-Options "nosniff" always;

External resources

X-Content-Type-Options HTTP Header

🔰 Deny the use of browser features (Feature-Policy)

Rationale

This header protects your site from third parties using APIs that have security and privacy implications, and also from your own team adding outdated APIs or poorly optimized images.

Example

add_header Feature-Policy "geolocation none; midi none; notifications none; push none; sync-xhr none; microphone none; camera none; magnetometer none; gyroscope none; speaker none; vibrate none; fullscreen self; payment none; usb none;";

External resources

🔰 Reject unsafe HTTP methods

Rationale

Set of methods support by a resource. An ordinary web server supports the HEAD, GET and POST methods to retrieve static and dynamic content. Other (e.g. OPTIONS, TRACE) methods should not be supported on public web servers, as they increase the attack surface.

Example

add_header Allow "GET, POST, HEAD" always;

if ($request_method !~ ^(GET|POST|HEAD)$) {

  return 405;

}

External resources

Vulnerability name: Unsafe HTTP methods

🔰 Control Buffer Overflow attacks

Rationale

Buffer overflow attacks are made possible by writing data to a buffer and exceeding that buffers’ boundary and overwriting memory fragments of a process. To prevent this in Nginx we can set buffer size limitations for all clients.

Example

client_body_buffer_size 100k;
client_header_buffer_size 1k;
client_max_body_size 100k;
large_client_header_buffers 2 1k;

External resources

SCG WS nginx

🔰 Mitigating Slow HTTP DoS attack (Closing Slow Connections)

Rationale

Close connections that are writing data too infrequently, which can represent an attempt to keep connections open as long as possible.

Example

client_body_timeout 10s;
client_header_timeout 10s;
keepalive_timeout 5s 5s;
send_timeout 10s;

External resources

Configuration examples

Remember to make a copy of the current configuration and all files/directories.

Nginx Contexts

Before read this configuration remember about Nginx Contexts structure:

Core Contexts:

  Global/Main Context
    Events Context
    HTTP Context
      Server Context
        Location Context
      Upstream Context
    Mail Context

Reverse Proxy

This chapter describes the basic configuration of my proxy server (for blkcipher.info domain).

Import configuration

It's very simple - clone the repo and perform full directory sync:

git clone https://github.com/trimstray/nginx-quick-reference.git
rsync -avur --delete lib/nginx/ /etc/nginx/

For leaving your configuration (not recommended) remove --delete rsync param.

Set bind IP address

Find and replace 192.168.252.2 string in directory and file names

cd /etc/nginx
find . -depth -name '*192.168.252.2*' -execdir bash -c 'mv -v "$1" "${1//192.168.252.2/xxx.xxx.xxx.xxx}"' _ {} \;

Find and replace 192.168.252.2 string in configuration files

cd /etc/nginx
find . -type f -print0 | xargs -0 sed -i 's/192.168.252.2/xxx.xxx.xxx.xxx/g'

Set your domain name

Find and replace blkcipher.info string in directory and file names

cd /etc/nginx
find . -depth -name '*blkcipher.info*' -execdir bash -c 'mv -v "$1" "${1//blkcipher.info/example.com}"' _ {} \;

Find and replace blkcipher.info string in configuration files

cd /etc/nginx
find . -type f -print0 | xargs -0 sed -i 's/blkcipher_info/example_com/g'
find . -type f -print0 | xargs -0 sed -i 's/blkcipher.info/example.com/g'

Regenerate private keys and certs

For localhost

cd /etc/nginx/master/_server/localhost/certs
# Private key + Self-signed certificate
( _fd="localhost.key" ; _fd_crt="nginx_localhost_bundle.crt" ; \
openssl req -x509 -newkey rsa:4096 -keyout ${_fd} -out ${_fd_crt} -days 365 -nodes \
-subj "/C=X0/ST=localhost/L=localhost/O=localhost/OU=X00/CN=localhost" )

For `default_server`

cd /etc/nginx/master/_server/defaults/certs
# Private key + Self-signed certificate
( _fd="defaults.key" ; _fd_crt="nginx_defaults_bundle.crt" ; \
openssl req -x509 -newkey rsa:4096 -keyout ${_fd} -out ${_fd_crt} -days 365 -nodes \
-subj "/C=X1/ST=default/L=default/O=default/OU=X11/CN=default_server" )

For your domain (e.g. Let's Encrypt)

cd /etc/nginx/master/_server/example.com/certs

# For multidomain:
certbot certonly -d example.com -d www.example.com --rsa-key-size 4096

# For wildcard:
certbot certonly --manual --preferred-challenges=dns -d example.com -d *.example.com --rsa-key-size 4096

# Copy private key and chain:
cp /etc/letsencrypt/live/example.com/fullchain.pem nginx_example.com_bundle.crt
cp /etc/letsencrypt/live/example.com/privkey.pem example.com.key

Add new domain

Updated `nginx.conf`

# At the end of the file (in 'IPS/DOMAINS' section)
include /etc/nginx/master/_server/domain.com/servers.conf;
include /etc/nginx/master/_server/domain.com/backends.conf;

Init domain directory

cd /etc/nginx/cd master/_server
cp -R example.com domain.com
cd domain.com
find . -depth -name '*example.com*' -execdir bash -c 'mv -v "$1" "${1//example.com/domain.com}"' _ {} \;
find . -type f -print0 | xargs -0 sed -i 's/example_com/domain_com/g'
find . -type f -print0 | xargs -0 sed -i 's/example.com/domain.com/g'

Test your configuration

nginx -t -c /etc/nginx/nginx.conf

Name		Name	Last commit message	Last commit date
Latest commit History 169 Commits
doc/img		doc/img
lib/nginx		lib/nginx
CODE_OF_CONDUCT.md		CODE_OF_CONDUCT.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE.md		LICENSE.md
README.md		README.md

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Nginx Quick Reference

My notes about Nginx...

Table of Contents

Introduction

General disclaimer

Contributing

SSL Report: blkcipher.info

Printable high-res hardening checklist

External Resources

About Nginx

References

Cheatsheets

Performance & Hardening

Config generators

Static analyzers

Log analyzers

Performance analyzers

Benchmarking tools

Online tools

Other stuff

Helpers

Shell aliases

Debugging

See the top 5 IP addresses in a web server log

Analyse web server log and show only 2xx http codes

Analyse web server log and show only 5xx http codes

Get range of dates in a web server log

Get line rates from web server log

Trace network traffic for all Nginx processes

List all files accessed by a Nginx

Base rules

🔰 Organising Nginx configuration

Rationale

Example

External resources

🔰 Separate listen directives for 80 and 443

Rationale

Example

External resources

🔰 Prevent processing requests with undefined server names

Rationale

Example

External resources

🔰 Use only one SSL config for specific listen directive

Rationale

Example

External resources

🔰 Force all connections over TLS

Rationale

Example

External resources

🔰 Use geo/map modules instead allow/deny

Rationale

Example

External resources

🔰 Map all the things...

Rationale

Example

External resources

🔰 Drop the same root inside location block

Rationale

Example

External resources

🔰 Use debug mode for debugging

Rationale

Example

External resources

🔰 Use custom log formats

Rationale

Example

External resources

Performance

🔰 Adjust worker processes

Rationale

`My notes about Nginx...`