The SSL Client Certificate is Not Being Requested by Apache

Question

The SSL Client Certificate is Not Being Requested by Apache

Hello there! I must admit that configuring SSL is a new task for me. In the past, I've always relied on my IT department to handle it for me. So, please bear with me if I need some clarification on your answers. 😅

My Goal

I am in the process of setting up an intranet website for employees within my company. The site will have a personalized browser start page tailored to each employee. To achieve this, I aim to identify users without requiring a username/password prompt every time they visit. Implementing SSL appears to be the most suitable solution for this scenario.

My plan involves using a MySQL database to link user accounts with unique identifiers from client certificates such as SSL_CLIENT_M_SERIAL and SSL_CLIENT_I_DN. I came across this approach in an article which you can find here:

When a user visits the internal website for the first time without a certificate, the system will guide them through a setup process involving PHP-generated SSL client certificates. Once installed by the user, the association is established, and after a browser restart, they can access the internal website seamlessly.

Apache should request the client's certificate at this point, which is then sent by the browser. A PHP script will verify the necessary $_SERVER variables against the MySQL database for authentication. It sounds like a straightforward process.

Progress So Far

I have successfully installed server-side certificates (self-signed for security). Mod_ssl in Apache is working correctly, and a PHP script confirms that all SSL_SERVER_* key values align with the server certificate.

The Issue

The problem arises with the client certificates. Despite several attempts, SSL_CLIENT_VERIFY always returns "NONE," and other SSL_CLIENT_* keys are absent. This occurs when SSLVerifyClient is set to optional in ssl.conf. Tutorials suggest that the webserver should prompt the browser for a client certificate, but that doesn't seem to happen. Both Firefox, Chrome, and IE behave similarly.

Changing SSLVerifyClient to required results in an inability to establish an SSL connection. Browsers display various errors, yet server logs show no activity during these connection attempts. This lack of feedback hinders troubleshooting efforts.

In desperation, I tried generating and installing a client certificate manually using PHP's OpenSSL extension. Though successful, I fail to associate it with the server certificate. Moreover, Apache still fails to request a client certificate under optional settings or crashes under required settings.

The Environment

OS: CentOS 5.7 64-bit (VirtualBox)

Apache: 2.2.3

PHP: 5.3.10

If more information is needed to assist me, feel free to ask! I'll provide whatever details you require.

To sum it up, I'm seeking guidance on how to prompt Apache to request an SSL client certificate based on the outlined conditions. Additionally, any insights on ensuring compatibility between client and server certificates (without manual intervention) would be greatly appreciated.

I'm currently at a standstill and unable to find solutions online. Any help or advice you can offer on this matter would be immensely valuable to me! Thank you in advance! 😊

php linux apache ssl openssl

Answer 1

Answer №1

To begin, it is essential to set up Apache Httpd to request a client certificate. This involves using SSLVerifyClient optional at the desired location/directory for authentication.

In addition, Apache Httpd must trust the certificates sent by the client. While SSLVerifyClient optional_no_ca can be used to allow any client certificate through the SSL/TLS stack of Apache Httpd and verify it within PHP, this approach may not be practical due to complexity. In your scenario where you control the CA, it would be more sensible to use SSLVerifyClient optional.

The variable SSL_CLIENT_VERIFY is primarily useful with SSLVerifyClient optional_no_ca, although it may work with SSLVerifyClient optional. A connection using SSLVerifyClient require will reject untrusted client certificates or connections without a certificate. On the other hand, SSLVerifyClient optional allows clients without a certificate or with a trusted certificate but rejects untrusted ones.

Rejecting the connection in this context means abruptly closing the SSL/TLS connection with an alert, resulting in a browser error message like

ssl_error_unknown_certificate_...

. Consider the usability implications of this action.

After configuring Apache Httpd, setting up your own CA becomes necessary. This process may involve web-based CA creation with in-browser key generation on the same website. It is important to configure SSLCACertificateFile to point to the CA certificate of your internal CA and ensure that browsers suggest only certificates issued by trusted CAs.

These steps, including CA setup and client-certificate usage on websites, are independent processes. You could test the Apache Httpd setup without deploying an entire CA first to understand the requirements better. Tools like OpenSSL's CA.pl and TinyCA can help create a manageable CA system.

While managing the certificates and mapping them to users from your MySQL DB is crucial, using variables like SSL_CLIENT_M_SERIAL and

SSL_CLIENT_I_DN</code is not recommended. Use <code>SSL_CLIENT_S_DN

for the client certificate Subject DN instead.

Considering the complexities involved, using client certificates for achieving your goal of allowing employees in your company to log on without passwords may not be the most efficient method. Implementing Single Sign-On (SSO) solutions like CAS, SAML-based systems, or Kerberos/SPNEGO might offer a simpler alternative.

Answer 2

To begin, it is essential to set up Apache Httpd to request a client certificate. This involves using SSLVerifyClient optional at the desired location/directory for authentication.

In addition, Apache Httpd must trust the certificates sent by the client. While SSLVerifyClient optional_no_ca can be used to allow any client certificate through the SSL/TLS stack of Apache Httpd and verify it within PHP, this approach may not be practical due to complexity. In your scenario where you control the CA, it would be more sensible to use SSLVerifyClient optional.

The variable SSL_CLIENT_VERIFY is primarily useful with SSLVerifyClient optional_no_ca, although it may work with SSLVerifyClient optional. A connection using SSLVerifyClient require will reject untrusted client certificates or connections without a certificate. On the other hand, SSLVerifyClient optional allows clients without a certificate or with a trusted certificate but rejects untrusted ones.

Rejecting the connection in this context means abruptly closing the SSL/TLS connection with an alert, resulting in a browser error message like

ssl_error_unknown_certificate_...

. Consider the usability implications of this action.

After configuring Apache Httpd, setting up your own CA becomes necessary. This process may involve web-based CA creation with in-browser key generation on the same website. It is important to configure SSLCACertificateFile to point to the CA certificate of your internal CA and ensure that browsers suggest only certificates issued by trusted CAs.

These steps, including CA setup and client-certificate usage on websites, are independent processes. You could test the Apache Httpd setup without deploying an entire CA first to understand the requirements better. Tools like OpenSSL's CA.pl and TinyCA can help create a manageable CA system.

While managing the certificates and mapping them to users from your MySQL DB is crucial, using variables like SSL_CLIENT_M_SERIAL and

SSL_CLIENT_I_DN</code is not recommended. Use <code>SSL_CLIENT_S_DN

for the client certificate Subject DN instead.

Considering the complexities involved, using client certificates for achieving your goal of allowing employees in your company to log on without passwords may not be the most efficient method. Implementing Single Sign-On (SSO) solutions like CAS, SAML-based systems, or Kerberos/SPNEGO might offer a simpler alternative.

Answer 3

Answer №2

I encountered a similar issue with:

Ubuntu 10.04
Nginx 1.14.0

After numerous attempts, I finally identified the source of my problem.

When I configure SSLVerifyClient optional or SSLVerifyClient optional_no_ca, along with specifying SSLCACertificateFile or SSLCACertificatePath, Nginx will only accept the client certificate if it is issued by the CA listed in the referenced file/path in the configuration.

Answer 4

I encountered a similar issue with:

Ubuntu 10.04
Nginx 1.14.0

After numerous attempts, I finally identified the source of my problem.

When I configure SSLVerifyClient optional or SSLVerifyClient optional_no_ca, along with specifying SSLCACertificateFile or SSLCACertificatePath, Nginx will only accept the client certificate if it is issued by the CA listed in the referenced file/path in the configuration.

Answer 5

Answer №3

Have you checked out the Apache documentation yet? If not, it might be helpful to review it.

The first step is to create your self-signed certificate and verify it before attempting to use it. From there, it seems like the client is accessing your intranet site via HTTP. There are various methods for transitioning to HTTPS with your SSL certificate, such as using the Apache rewrite module or redirecting through PHP and MySQL, which can be a bit more complex.

In either scenario (automatic redirect via mod_rewrite in Apache or cascading redirects through PHP/JavaScript/HTML), you'll need to configure two virtual hosts - one for HTTP and one for HTTPS - properly based on specific assumptions.

For instance, in an automatic redirect setup using Apache (e.g., Debian - Apache 2.2), here's how you could configure the HTTP virtual host:

# VHOST test

<VirtualHost *:80>

    DocumentRoot /home/www/test
    ServerName www.test.dev

    # Redirect rules
    RewriteEngine on
    RewriteOptions Inherit

    RewriteCond %{HTTP_HOST}   ^www\.test\.dev [NC]
    RewriteCond %{HTTP_HOST}   !^$
    RewriteRule ^(.*)/$ /index.php

    RewriteCond %{HTTP_HOST}   ^www\.test\.dev [NC]
    RewriteCond %{HTTP_HOST}   !^$
    RewriteCond %{SERVER_PORT} ^80$
    RewriteCond %{REQUEST_URI} /
    RewriteRule ^/(.*)$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R]

</VirtualHost>

And here's a snippet for configuring the SSL virtual host:

# VHOST for ssl

DocumentRoot "/home/www/test"
ServerName www.test.dev

SSLEngine on
SSLCACertificateFile /etc/apache2/ssl/cur_cert/ca.pem
...

</VirtualHost>

In your case, you may have a simpler configuration with just a basic HTTP virtual host and a separate HTTPS (SSL) virtual host without any redirection logic. You can handle the switch from HTTP to HTTPS after performing MySQL checks using PHP, JavaScript, and HTML, as demonstrated below:

public function Redirect($url){

    if (TRUE !== Validator::isValidURL($url))
        die ("FATAL ERR: url not valid");

    if (!headers_sent()) {
        header("Status: 200");
        ...

    } else {
        echo '<script type="text/javascript">';
        ...
        exit();
    }

    return FALSE;

}

I hope this explanation assists you in understanding how to proceed and tailor these techniques to suit your unique requirements.

Answer 6

Have you checked out the Apache documentation yet? If not, it might be helpful to review it.

The first step is to create your self-signed certificate and verify it before attempting to use it. From there, it seems like the client is accessing your intranet site via HTTP. There are various methods for transitioning to HTTPS with your SSL certificate, such as using the Apache rewrite module or redirecting through PHP and MySQL, which can be a bit more complex.

In either scenario (automatic redirect via mod_rewrite in Apache or cascading redirects through PHP/JavaScript/HTML), you'll need to configure two virtual hosts - one for HTTP and one for HTTPS - properly based on specific assumptions.

For instance, in an automatic redirect setup using Apache (e.g., Debian - Apache 2.2), here's how you could configure the HTTP virtual host:

# VHOST test

<VirtualHost *:80>

    DocumentRoot /home/www/test
    ServerName www.test.dev

    # Redirect rules
    RewriteEngine on
    RewriteOptions Inherit

    RewriteCond %{HTTP_HOST}   ^www\.test\.dev [NC]
    RewriteCond %{HTTP_HOST}   !^$
    RewriteRule ^(.*)/$ /index.php

    RewriteCond %{HTTP_HOST}   ^www\.test\.dev [NC]
    RewriteCond %{HTTP_HOST}   !^$
    RewriteCond %{SERVER_PORT} ^80$
    RewriteCond %{REQUEST_URI} /
    RewriteRule ^/(.*)$ https://%{SERVER_NAME}%{REQUEST_URI} [L,R]

</VirtualHost>

And here's a snippet for configuring the SSL virtual host:

# VHOST for ssl

DocumentRoot "/home/www/test"
ServerName www.test.dev

SSLEngine on
SSLCACertificateFile /etc/apache2/ssl/cur_cert/ca.pem
...

</VirtualHost>

In your case, you may have a simpler configuration with just a basic HTTP virtual host and a separate HTTPS (SSL) virtual host without any redirection logic. You can handle the switch from HTTP to HTTPS after performing MySQL checks using PHP, JavaScript, and HTML, as demonstrated below:

public function Redirect($url){

    if (TRUE !== Validator::isValidURL($url))
        die ("FATAL ERR: url not valid");

    if (!headers_sent()) {
        header("Status: 200");
        ...

    } else {
        echo '<script type="text/javascript">';
        ...
        exit();
    }

    return FALSE;

}

I hope this explanation assists you in understanding how to proceed and tailor these techniques to suit your unique requirements.

The SSL Client Certificate is Not Being Requested by Apache

Answer №1

Answer №2

Answer №3

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