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In our previous post, we showed you how to use socat, ssh, and some fancy footwork to pipe a UDP-based request coming from Net::Growl, through a TCP-based reverse-proxy ala SSH, and back to the Mac as a UDP-request straight to Growl.

What happens if you’ve got more than one person wanting to do the same thing from that same shell server? Aside from everyone agreeing on a few ports they’d like to reserve for their Growl activities, here’s the skinny.

The problem

When we first wanted to do this, the only technology hurdle, was that Net::Growl in its current incarnation does not support passing a unique UDP port in the register and notify calls. Not a big deal, here’s what you do to fix:

1. Download Net::Growl distribution to your linux machine
2. Apply this patch to the distribution
3. Rebuild it via: perl Makefile.PL, make, sudo make install

If you’re using our super fancy growl-net-notify.pl script for Weechat, it is already set up to pass a different UDP port by changing the settings in the /growl setup call.

Scenarios

For the TCP side of the equation, you’ll each have to pick your own TCP port (above 1024 of course) to reverse-proxy with. In my previous example I chose 9999, so you can have others choose 9900, 9901, 9902, whatever flows off the tongue.

On the local side, socat and your ssh reverse-proxy will change, but using UDP 9887 will not. Growl is listening there.

On the linux side, where weechat + screen is running, we’ll use whatever our agreed upon TCP port was, and pick our own UDP port to pass messages to from Weechat. This is easily modified from growl-net-notify using /growl setup [host] [pass] [port] where port is whatever your agreed Growl port is going to be. And setup socat to use your agreed upon TCP port, and agreed upon UDP port and do a /growl test hello, world!

Examples

A lot of times reading manuals, I skim through to read the examples, in man pages its usually near the bottom. I need to see the commands in action. So here is an example with a situation you’re likely to run into.

2 people using the same host for IRC. For the sake of example, we’ll use the names: Steve and Andrew.

Steve will use: TCP 9900 and UDP 9889

On the Mac side the commands he’ll use:

% socat TCP-LISTEN:9900,reuseaddr,fork UDP:127.0.0.1:9887 &
% ssh myserver -R 9900:127.0.0.1:9900

On the Linux side the commands he’ll use:

socat UDP-LISTEN:9889,reuseaddr,fork TCP:127.0.0.1:9900 &

And from within Weechat’s growl

/growl setup localhost mypass 9889

Andrew will use the defaults: TCP 9999 and UDP 9887

socat TCP-LISTEN:9999,reuseaddr,fork UDP:127.0.0.1:9887 &
ssh myserver -R 9999:127.0.0.1:9999

On the Linux side the commands he’ll use:

socat UDP-LISTEN:9887,reuseaddr,fork TCP:127.0.0.1:9999 &

And from within Weechat’s growl

/growl setup localhost mypass 9887

It’s that simple.