Your advice helped considerably. Thank you.<br><br>Sean M Hollingsworth<br><br><div class="gmail_quote">On Sat, Aug 8, 2009 at 4:49 PM, <span dir="ltr"><<a href="mailto:exarkun@twistedmatrix.com">exarkun@twistedmatrix.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">On 6 Aug, 03:47 pm, <a href="mailto:smhollingsworth@gmail.com">smhollingsworth@gmail.com</a> wrote:<br>
>I 19ve got an app written that runs as a service using<br>
<div class="im">>twisted.application.service that I need to tunnel through SSH. Right<br>
>now, I<br>
>use a script that makes use of Paramiko (and runs separate from my app)<br>
>to<br>
</div>>set up a tunnel. That more or less works, but I 19ve had some problems<br>
<div class="im">>with<br>
>the tunnel just going away and would like to integrate the tunneling<br>
>into<br>
</div>>the app, using conch. I 19ve found an example of tunneling via conch, at<br>
<div class="im">><a href="http://twistedmatrix.com/pipermail/twisted-" target="_blank">http://twistedmatrix.com/pipermail/twisted-</a><br>
>python/2009-February/019196.html,<br>
>that I think I can use as a base to add the code to my app.<br>
><br>
>Right now my app is basically:<br>
><br>
>class DataPuller(service.Service):<br>
> ...Code for my app...<br>
> ... The app pulls data from a database and I can only connect to the<br>
>server via SSH...<br>
><br>
</div>>application = service.Application( 18Data_puller 19)<br>
<div class="im">>dpService = DataPuller()<br>
>dpService.setServiceParent(application)<br>
><br>
</div>>My main problems are that I 19m not sure whether or not the example<br>
<div class="im">>linked to<br>
>above is a good one for tunneling with conch and, if it is, how do I<br>
>merge<br>
>the example tunneling code with my app code. From the example, where<br>
>the<br>
>code is:<br>
<br>
</div>The example you linked to sets up the traditional port forwarding<br>
behavior.<br>
A local port is opened and connections to it are tunneled over the SSH<br>
connection, where data is then delivered to some address accessible from<br>
the server on the other end of the SSH connection.<br>
<br>
This is fine and should work, and probably very closely mirrors what<br>
you're<br>
doing with Paramiko, so if you're happy with that, you should go for it.<br>
<br>
However, it's also possible for you to do this tunneling without opening<br>
the extra local port. Since your application and the SSH client code<br>
are<br>
all in the same process, you don't need the TCP connection to a local<br>
port<br>
to do this IPC to interact wiht the tunnel. You can set up the tunnel<br>
part<br>
of things, but instead of binding a local port to accept connections on,<br>
you can just open a connection over the tunnel and write bytes into it<br>
with<br>
API calls.<br>
<br>
I *don't* have an example of doing things this way, and I don't even<br>
know<br>
exactly what it involves. ;) However, the example you linked to gives a<br>
clue about where to start on this approach: when it binds the local<br>
port,<br>
it uses the forwarding.SSHListenForwardingFactory factory, so I'd start<br>
by looking at that class and see what it does. The rest is just<br>
mimicking<br>
its behavior without actually using reactor.listenTCP.<br>
<div class="im">>class Connection(connection.SSHConnection):<br>
> .<br>
> .<br>
> .<br>
> def serviceStarted(self):<br>
><br>
>Do I instantiate my DataPuller class there, in serviceStarted (and not<br>
>subclass from service.Service)? If so, how do I wrap the tunneling code<br>
>so<br>
>that I can make it a service? If not, do I need put the tunneling code<br>
>inside my DataPuller class? What would that look like?<br>
<br>
</div>If you want things to happen when your program starts or when it is<br>
about<br>
to stop, then using service.Service is still a good idea. That's the<br>
easy<br>
way to hook into startup and shutdown events. However, you may not want<br>
to do anything other than set up (or tear down) the SSH connection in<br>
your<br>
service.Service subclass. Creating your new non-Service DataPuller in<br>
the<br>
Connection's serviceStarted (or maybe even a little later - after you<br>
actually set up the connection over the tunnel over the connection) then<br>
makes sense.<br>
<br>
Jean-Paul<br>
<br>
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</blockquote></div><br>