Checking out Unfuddle'd code from behind a firewall

I have been using Unfuddle for a while now. Besides relieving me from having to setup and maintain a SVN server, the ticketing system makes it easy for my clients, my partners and myself to keep the communication / feedback channels simple and straight-forward.

When I setup a new project, I usually create a user that has read-only access to the repository. This allows for easy and secure checkouts and updates on the server. While trying to checkout a project on a machine, I recently came across the following error message:

$ svn co https://user@example.unfuddle.com/svn/project ./
svn: REPORT request failed on '/svn/project/!svn/vcc/default'
svn: REPORT of '/svn/project/!svn/vcc/default': Could not read status line: 
     connection was closed by server. (https://example.unfuddle.com)

The answers I found suggested that a potential cause for this problem was a version conflict between the SVN client and server. After trying a few different configuration, it turned out that the problem came from the firewall.

Here's the email I received from the very responsive Unffudle support team:

If you are accessing your Subversion repository over HTTP then port 80 should be sufficient (or port 443 if HTTPS). Additionally, Subversion uses some extensions to the standard HTTP methods which may also be blocked by certain firewalls. In order to use Subversion in these instances you will need to modify the firewall to also allow these "extra" methods as well.

You can find a list of these methods here: http://subversion.tigris.org/faq.html#http-methods