The following is a link to the online source repository.
The source can be checked out anonymously from SVN with this command:
$ svn checkout https://j-trac.svn.sourceforge.net/svnroot/j-trac/trunk/jtrac jtrac
Refer to the documentation of the SCM used for more information about an access behind a firewall.
The Subversion client can go through a proxy, if you configure it to do so. First, edit your "servers" configuration file to indicate which proxy to use. The files location depends on your operating system. On Linux or Unix it is located in the directory "~/.subversion". On Windows it is in "%APPDATA%\Subversion". (Try "echo %APPDATA%", note this is a hidden directory.)
There are comments in the file explaining what to do. If you don't have that file, get the latest Subversion client and run any command; this will cause the configuration directory and template files to be created.
Example : Edit the 'servers' file and add something like :
[global] http-proxy-host = your.proxy.name http-proxy-port = 3128