Saturday, October 16, 2010

Apache, Virtual Hosts, and HTTPS

Apache cannot use https with name-based virtual hosts due to the way the SSL handshake works. I've run across this problem several times in the past, and I always forget how to solve it. So I'll record it here for posterity.

To get things working, the Apache setup needs to be changed from name-based virtual hosting to ip-based virtual hosting. After configuring a separate ip for each vhost that requires https, the Apache config files (/etc/httpd/conf/ on RHEL, Apache 2.2) need to be updated to use ip-based virtual hosting.

If name-based vhosting was previously configured, it will need to be modified. If all vhosts are being converted to ip-based vhosting, then name-based vhosting can be completely turned off by commenting or deleting any 'NameVirtualHost' directives. However, it is also possible to continue to use name-based vhosting for vhosts that do not require https. Any existing 'NameVirtualHost' directives that contain wildcards ('NameVirtualHost *:80') will need to be modified. Replace the wildcard with the ip that will be shared by name-based vhosts.

Next, modify any existing 'VirtualHost' directives that contain wildcards in their definition ('VirtualHost *:80'). Replace the wildcard with the ip that the vhost will be using. Virtual hosts that do not require HTTPS can continue to use name-based virtual hosting, and can share the same ip, but all vhosts that require HTTPS must use a unique ip address.

Finally, configure a 'VirtualHost' directive for each ip-based vhost in the ssl section of the Apache configuration file ('/etc/httpd/conf.d/ssl.conf' on RHEL, Apache 2.2). Any name-based vhosts will continue to share the ssl config within the '_default_:80' 'VirtualHost' directive. Restart Apache for the changes to take affect.

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