This short HOWTO explains how to set up the excellent nginx to work with a SSL certificate released from a CA. The whole process is fairly easy, but not completely straightforward.

I’m assuming the host name for which the certificate will be set up is www.domain.ext and the operating system is Gentoo Linux (the process shouldn’t be too different with another OS, though). Also, in my example I’m assuming that the certificate is a PositiveSSL from Comodo: using any other equivalent certificate should not make much difference.

First of all, make sure you have OpenSSL and that nginx is compiled with ssl support. In order to create your private key and the certificate request, I suggest you cd to you web server directory:

cd /etc/nginx

before generating the needed files with these two commands:

openssl genrsa -des3 -out www.domain.ext.key 2048
openssl req -new -key www.domain.ext.key -out www.domain.ext.csr

When, after issuing the second command, you are asked for the Common Name, be sure to enter the name of the host where you want to use you certificate, i.e.:


This will only work for https://www.domain.ext, and not for https://domain.ext or https://anyotherthing.domain.ext. Wildcard certificates exist, but they’re more expensive: they seem to not be so useful, but they are for instance needed to make SSL name-based virtual hosts (these have some caveats, though).

OK, now you have the certificate request file, www.domain.ext.csr: go to your CA and upload it. After the verifications (which in most cases are just the verification of an e-mail address inside the domain), you’ll get a download link for the certificate, which will likely be a ZIP file. This file contains the certificate (a file named domain.ext.crt or something similar) and maybe the CA “intermediate” certificate (which in case of PositiveSSL is named positive_bundle.crt).

At this point you have all the needed files, but a couple of actions still need to be performed. If you entered a password when creating the private key with OpenSSL, you’ll now most likely want to remove it, otherwise nginx will always prompt you for it when starting (which is not so handy):

cp www.mydomain.ext.key www.mydomain.ext.key.orig
openssl rsa -in www.mydomain.ext.key.orig -out www.mydomain.ext.key

If the file you received from the CA also contained one or more intermediated certificates, you’ll need to concatenate them because nginx want a single file:

cat www.domain.ext.crt positive_bundle.crt > www.domain.ext.pem

Be sure to put your server certificate file at the beginning of the concatenated pem file, as in the example below: otherwise, nginx will pick the wrong one up.

For the sake of security you’d better make all these files readable only by root user:

# Also chown or nginx won't be able to read the files
chown nginx:nginx *.pem *.key *.csr *.crt *.orig
chmod 600 *.pem *.key *.csr *.crt *.orig

The final step is the configuration of the web server. Nginx is incredibly powerful but also extraordinarily easy to manage. Open nginx.conf and add something similar to the following (have a look at nginx documentation for more options):

server {
        server_name www.domain.ext;

        ssl on;
        ssl_certificate /etc/nginx/www.domain.ext.pem;
        ssl_certificate_key /etc/nginx/www.domain.ext.key;

        access_log /var/log/nginx/www.domain.ext.access_log main;
        error_log /var/log/nginx/www.domain.ext.error_log info;

        root  /usr/local/domains/www.domain.ext;

You should be all set and ready to go now!