Re: [PLUG] setting up a socket service...

[Tobias DiPasquale <toby@cbcg.net>]

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On Nov 10, 2004, at 4:48 PM, George Gallen wrote:
> I want to setup a socket service.
>
> The program just needs to listen on a port#, when
>   a connection is established (can only be one at a time) it needs to
>   run a command locally, then send back the results of that command.
>
> How do setup xinetd to run the program on command.
>
> I thought about just having a program just listen, do when connected, 
> release, repeat
> but if the program stops running, obviously the service stops as well.

I'm going to go out on a limb and ask what this is for. The reason I 
ask is that, with the above description, two things are evident:

1. Its quite easy to monopolize and DoS this service.
2. Are you _SURE_ you want clients to connect and send commands? Why 
isn't RPC good enough for this?

Having said that:

daemontools is an excellent solution for creating arbitrary network 
services easily. The daemonization and respawning are handled by 
daemontools, as is log rotation and expiry via multilog. Check out 
http://cr.yp.to/daemontools.html for more information on that software.

Alternatively, you could run the program under xinetd by simply adding 
a file in /etc/xinetd.d. Here's an example:

# cat > /etc/xinetd.d/yourservice <<EOF
service yourservice
{
	type			= INTERNAL UNLISTED
	id			= yourservice-stream
	socket_type	= stream
	protocol		= tcp
	user			= root
	wait			= yes
	server		= /usr/local/bin/yourservicebinary
	server-args	= --some-kind-of-argument
	only_from		= 127.0.0.1
}
EOF

xinetd.conf(5) has all the specifics on what goes where in this file. 
Yours will probably look like the above somewhat. Check out the 
existing files for examples, too.

- --
Tobias DiPasquale
202A 04C4 2CE6 B985 8520  88D6 CD25 1A6C B9B5 1595
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