OpenSSH, which can only be described as the best utility of all time, is quite a versatile tool one feature people use frequently is port forwarding. This allows you to open a port on your computer that forwards the data over the SSH connection to the destination you specify, very useful when needing access to the an intranet web server when you don’t have a proper VPN set up for example. However, SSH can also do this in reverse! It opens a listening port up on the remote machine which then relays data to the destination you specify. For example you can SSH into a remote host and get SSH to open a port on that host which relays data back to the SSH port on the machine you are connection from, thereby allowing SSH access to a machine where it would normally be impossible.

A practical example:

chris@ktulu:~$ ssh sandman.cs278.org -R 2222:localhost:22

This connects to the server sandman.cs278.org and opens port 2222 which forwards traffic to localhost:22 (localhost is the machine I am connecting from). Once logged into the server I can do this:

chris@sandman:~$ ssh localhost -p 2222

Which opens a connection back to the remote machine.

• 5060 – 5100/udp
• 8000 – 8012/udp
• 5004/udp
• 10000/udp
• 3478 – 3497/udp
• 3478 – 3497/tcp
• 1720/udp
• 30000 – 30010/tcp

I am sure they could be refined and there maybe some that are unnecessary but it Works or Me™, use them at your own risk.

svn: PROPFIND request failed on '/~name'
svn: PROPFIND of '/~name': 405 Method Not Allowed (http://svn.example.com)

This stuck me as odd, it seemed the Apache was not serving the repository URI using the WebDAV module. When I gave up on an earlier attempt I reverted to using SVNParentPath and accessing the repository over the URI http://svn.example.com/~name/repos/ which worked perfectly and I couldn’t spot why. Turns out I made a single character mistake, my Apache configuration was set to use the path of /~name/ I should have used /~name because SVN truncates the trailing slash even if you specify it on the command line. Bugger!

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The trick is to open the configuration editor (Edit -> Preferences -> Advanced) and set the mail.check_all_imap_folders_for_new preference to true. Bingo!

1. First we need to install the dependencies.

   $ sudo aptitude install libdigest-sha{,1}-perl libemail-{address,mime-encodings}-perl libnet-{dns,server}-perl libcrypt-openssl-rsa-perl liberror-perl make libmailtools-perl

2. $ sudo cpan install Mail::DKIM

3. $ perl Makefile.PL
   $ make
   $ make install

4. $ ./configure --prefix=/usr/local
   $ make install

5. $ sudo adduser --system --shell /bin/false --home /var/run/dkimproxy --group dkimproxy

6. $ sudo mkdir /etc/dkimproxy/
   $ cd /etc/dkimproxy/
   $ sudo openssl genrsa -out private.key 1024
   $ sudo openssl rsa -in private.key -pubout -out public.key
   $ sudo chown -R root:dkimproxy .
   $ sudo chmod -R a=,u=rwX,g=rX,o=rX .
   $ sudo chmod o= private.key

Sorry, this solution will not run nicely on my NSLU2 so I have abandoned the rest of this documentation – it should help you somewhat though, hence I am publishing it anyway.