talk about SSLVerifyClient required vs. optional

diff --git a/doc/apache-client-certs.mdwn b/doc/apache-client-certs.mdwn
index da598d5f3524087d49bf4e4fd33b676b56551266..841e103c57f0a9040cdf29fae418b76a855cbc31 100644 (file)
--- a/doc/apache-client-certs.mdwn
+++ b/doc/apache-client-certs.mdwn
@@ -20,12 +20,14 @@ You'll also need a working AFS client and the Athena client certificate CA. Both
 
 In addition to the standard Apache directives needed to enable SSL, you'll need a few more before the Apache modules work as they do on scripts. Add the following directives to each vhost that will be using SSL client-side certificate authentication:
 
-    SSLVerifyClient require
+    SSLCACertificateFile /etc/ssl/clientCAs.pem
     <Location />
         AuthSSLCertVar SSL_CLIENT_S_DN_Email
         AuthSSLCertStripSuffix "@MIT.EDU"
     </Location>
 
+You also need to require certificate authentication. You can either use `SSLVerifyClient required` or `SSLVerifyClient optional`. `SSLVerifyClient required` has the downside that, if visitors don't have client-side certificates, they'll get an obscure OpenSSL error. However, Safari will not present certificates to a site with `SSLVerifyClient optional` set unless the user sets up an Identity Preference. For reference, scripts.mit.edu sets `SSLVerifyClient optional`.
+
 You'll also need to enable the Apache modules.
 
     # a2enmod auth_sslcert