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Setting up a webserver to use HTTPS

A straightforward article on configuring an HTTPS webserver with OpenSSL certificates.
Image
Securing web services with https
Image by MSA-90 from Pixabay

This article discusses and demonstrates the steps to install and configure an httpd service to serve content over HTTPS. The purpose of using HTTPS rather than basic HTTP is that the content is encrypted while it's in transit. This means that if somebody captures the traffic between your system and the webserver, they won't be able to see what was being sent. If you were accessing a basic HTTP server, they could see the content.

The prerequisites

To begin, the environment we'll use is a basic Red Hat Enterprise Linux (RHEL) 8.2 virtual machine. Make sure the system is registered to either a Red Hat Satellite or to the Red Hat Customer Portal. For assistance with that, please see the Registration Assistant.

After the system is registered and the correct subscriptions are attached, install httpd and mod_ssl:

[root@webserver ~]# dnf install httpd mod_ssl
### Output truncated ###

Installed:
  apr-1.6.3-9.el8.x86_64                                                         apr-util-1.6.1-6.el8.x86_64                                                       
  apr-util-bdb-1.6.1-6.el8.x86_64                                                apr-util-openssl-1.6.1-6.el8.x86_64                                               
  httpd-2.4.37-21.module+el8.2.0+5008+cca404a3.x86_64                            httpd-filesystem-2.4.37-21.module+el8.2.0+5008+cca404a3.noarch                    
  httpd-tools-2.4.37-21.module+el8.2.0+5008+cca404a3.x86_64                      mod_http2-1.11.3-3.module+el8.2.0+7758+84b4ca3e.1.x86_64                          
  mod_ssl-1:2.4.37-21.module+el8.2.0+5008+cca404a3.x86_64                        redhat-logos-httpd-81.1-1.el8.noarch                                              

Complete!
[root@webserver ~]#

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Generating certificates

After the RPMs are installed, generate certificates from a CA of your choice, if you don’t already have them:

[root@webserver ~]# openssl req -newkey rsa:2048 -nodes -keyout /etc/pki/tls/private/httpd.key -x509 -days 3650 -out /etc/pki/tls/certs/httpd.crt
Generating a RSA private key
..............+++++
..........................................................................+++++
writing new private key to '/etc/pki/tls/private/httpd.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields, but you can leave some blank
For some fields, there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:US
State or Province Name (full name) []:North Carolina
Locality Name (eg, city) [Default City]:Holly Springs
Organization Name (eg, company) [Default Company Ltd]:Example Co
Organizational Unit Name (eg, section) []:Example Unit
Common Name (eg, your name or your server's hostname) []:webserver
Email Address []:root@localhost

[root@webserver ~]#

You can verify the files were created:

[root@webserver ~]# ls -l /etc/pki/tls/private/ /etc/pki/tls/certs/
/etc/pki/tls/certs/:
total 4
lrwxrwxrwx. 1 root root   49 Oct 18  2019 ca-bundle.crt -> /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem
lrwxrwxrwx. 1 root root   55 Oct 18  2019 ca-bundle.trust.crt -> /etc/pki/ca-trust/extracted/openssl/ca-bundle.trust.crt
-rw-r--r--. 1 root root 1489 Oct  1 12:02 httpd.crt

/etc/pki/tls/private/:
total 4
-rw-------. 1 root root 1704 Oct  1 12:00 httpd.key

Now that the certificates have been generated, you need to create a directory from which your webserver will serve the content. For example:

[root@webserver ~]# mkdir /var/www/https

You can put sample content in the index.html file there:

[root@webserver ~]# echo secure content > /var/www/https/index.html
[root@webserver ~]# cat /var/www/https/index.html
secure content
[root@webserver ~]#

SELinux security

Verify that the correct SELinux context is set:

[root@webserver ~]# ll -Z /var/www
total 0
drwxr-xr-x. 2 root root system_u:object_r:httpd_sys_script_exec_t:s0 6 Dec  2  2019 cgi-bin
drwxr-xr-x. 2 root root system_u:object_r:httpd_sys_content_t:s0     6 Dec  2  2019 html
drwxr-xr-x. 2 root root unconfined_u:object_r:httpd_sys_content_t:s0 6 Oct  1 12:34 https

[root@webserver ~]#

Also verify the SELinux context is correct for your index.html file:

[root@webserver ~]# ll -Z /var/www/https/index.html
-rw-r--r--. 1 root root unconfined_u:object_r:httpd_sys_content_t:s0 15 Oct  1 15:07 /var/www/https/index.html

[root@webserver ~]#

Now that you have the right certificates, the directory has been created, and SELinux is correct, tell httpd to use the keys:

[root@webserver ~]# vi /etc/httpd/conf.d/ssl.conf
[root@webserver ~]# grep -e httpd.crt -e httpd.key /etc/httpd/conf.d/ssl.conf -B1
#SSLCertificateFile /etc/pki/tls/certs/localhost.crt
SSLCertificateFile /etc/pki/tls/certs/httpd.crt
--
#SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
SSLCertificateKeyFile /etc/pki/tls/private/httpd.key
[root@webserver ~]#
[root@webserver ~]# grep DocumentRoot /etc/httpd/conf.d/ssl.conf
DocumentRoot "/var/www/https"
#DocumentRoot "/var/www/html"

[root@webserver ~]#

Firewall settings

The httpd service has now been configured, but we need to make sure that traffic is allowed through the firewall. We'll enable port 443, and then reload the firewall:

[root@webserver ~]# firewall-cmd --permanent --add-port=443/tcp
success

[root@webserver ~]# firewall-cmd --reload
success

Final configuration and testing

Enable the httpd service to start at boot and then restart the httpd service:

[root@webserver ~]# systemctl enable httpd
Created symlink /etc/systemd/system/multi-user.target.wants/httpd.service → /usr/lib/systemd/system/httpd.service.
[root@webserver ~]# systemctl restart httpd
[root@webserver ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2020-10-01 12:35:26 EDT; 1min 30s ago
     Docs: man:httpd.service(8)
 Main PID: 33387 (httpd)
   Status: "Total requests: 1; Idle/Busy workers 100/0;Requests/sec: 0.0112; Bytes served/sec:  40 B/sec"
    Tasks: 213 (limit: 74790)
   Memory: 35.6M
   CGroup: /system.slice/httpd.service
           ├─33387 /usr/sbin/httpd -DFOREGROUND
           ├─33390 /usr/sbin/httpd -DFOREGROUND
           ├─33391 /usr/sbin/httpd -DFOREGROUND
           ├─33392 /usr/sbin/httpd -DFOREGROUND
           └─33393 /usr/sbin/httpd -DFOREGROUND

Oct 01 12:35:26 webserver.example.com systemd[1]: Starting The Apache HTTP Server...
Oct 01 12:35:26 webserver.example.com systemd[1]: Started The Apache HTTP Server.
Oct 01 12:35:26 webserver.example.com httpd[33387]: Server configured, listening on: port 443, port 80

[root@webserver ~]#

You can verify that the service is running and listening on port 443 by using netstat:

[root@webserver ~]# netstat -tlpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 192.168.124.1:53        0.0.0.0:*               LISTEN      1505/dnsmasq       
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1438/sshd          
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      1904/cupsd         
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      1/systemd          
tcp6       0      0 :::80                   :::*                    LISTEN      33387/httpd        
tcp6       0      0 :::22                   :::*                    LISTEN      1438/sshd          
tcp6       0      0 ::1:631                 :::*                    LISTEN      1904/cupsd         
tcp6       0      0 :::443                  :::*                    LISTEN      33387/httpd        
tcp6       0      0 :::111                  :::*                    LISTEN      1/systemd          

[root@webserver ~]#

At this point, the web service should be correctly working and visible to your clients. To verify that, try using your web browser to get to the site. If you're using a self-signed certificate, you'll need to accept it:

Image
Browser warning page prompting you to accept the self-signed certificate

By clicking the lock icon in the address bar and then selecting "View Certificate," you'll see the certificate information that you entered:

Image
The "View Certificate" contents, including the identity information you entered

You will be able to see the content in the /var/www/https/index.html file being served to you over HTTPS:

Image
Web browser tab displaying the secure content of the /var/www/https/index.html file.

[ Want to learn more about security? Check out the IT security and compliance checklist. ] 

Wrap up

This article has shown you how to install and configure an HTTPS server and then verify that the service is working correctly. Additional configurations might include setting up remote logging, enabling PHP, or a configuring database for the website.

Check out these related articles on Enable Sysadmin

Topics:   Linux   Linux Administration   Security   Web servers  
Author’s photo

Peter Gervase

I currently work as a Solutions Architect at Red Hat. I have been here for going on 14 years, moving around a bit over the years, working in front line support and consulting before my current role. In my free time, I enjoy spending time with my family, exercising, and woodworking. More about me

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