Generating a nonce for your application does not involve recompiling nginx anymore, thanks to dynamic modules!
Compile Dynamic Modules
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Get needed nginx modules
Check the current version of nginx you’re using, then download the sources here: https://nginx.org/en/download.html
Download the [Nginx Development Kit](https://github.com/simpl/ngx_devel_kit/releases) and the [set-misc-module](https://github.com/openresty/set-misc-nginx-module/releases).
Extract the archives so that your folder structure looks like this:
- nginx - nginx-1.17.10 - ngx_devel_kit-0.3.1 - set-misc-nginx-module-0.32 -
Configure Arguments
Grab the configure arguments of the nginx version currently installed on your server:
nginx -VThe output should look like this:
nginx version: nginx/1.17.10 (Ubuntu) built with OpenSSL 1.1.1f 31 Mar 2020 TLS SNI support enabled configure arguments: --with-cc-opt='-g -O2 -fdebug-prefix-map=/build/nginx-Pmk9_C/nginx-1.17.10=. -fstack-protector-strong -Wformat -Werror=format-security -fPIC -Wdate-time -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -fPIC' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --modules-path=/usr/lib/nginx/modules --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-compat --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_v2_module --with-http_dav_module --with-http_slice_module --with-threads --with-http_addition_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module=dynamic --with-http_sub_module --with-http_xslt_module=dynamic --with-stream=dynamic --with-stream_ssl_module --with-mail=dynamic --with-mail_ssl_moduleSave the arguments somewhere and add the references to
ngx_devel_kitandset-misc-nginx-moduleto it:--add-dynamic-module=../ngx_devel_kit-0.3.1 --add-dynamic-module=../set-misc-nginx-module-0.32Run
./configurewith your arguments. -
Compile the modules
It’s time to compile now!
cd nginx-1.17.10 make modulesIf compilation was successful, check the
objsfolder for these files:ngx_http_set_misc_module.so ndk_http_module.sobash
Load modules in Nginx
Upload the .so files to your server and put them in
/usr/lib/nginx/modules.
Now edit your nginx.conf and load them before the http block:
load_module /usr/lib/nginx/modules/ndk_http_module.so;
load_module /usr/lib/nginx/modules/ngx_http_set_misc_module.so;
Generate and Replace Nonce
Open your virtual host file and put the following lines in the server
block, replacing <NONCE_PLACEHOLDER> with a string of your choice:
> Use a unique value for <NONCE_PLACEHOLDER> and keep it safe!
# Generate and Replace NONCE
set_secure_random_alphanum $cspNonce 32;
sub_filter_once off;
sub_filter_types *;
sub_filter <NONCE_PLACEHOLDER> $cspNonce;Update CSP Header
Update your CSP Header to include your nonce:
add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'nonce-$cspNonce'; object-src 'none'; style-src 'self' 'nonce-$cspNonce'; img-src 'self' data: blob:; media-src 'self'; frame-src 'none'; font-src 'self'; connect-src 'self'";Add Nonce to your application
Add the following meta tag to the head of your html, replacing
<NONCE_PLACEHOLDER> with your nonce-string:
<meta name="csp-nonce" content="<NONCE_PLACEHOLDER>" />The nonce-string will be replaced by nginx with a unique nonce everytime the page is loaded.