Re: Script to temporarily "open" port

[David Baron <d_baron@012.net.il>]

On Tuesday 28 December 2004 17:39, Laurent CARON wrote:
> >A home system with an email server, i.e. exim, need not lay "exposed"
> > 24/7. Is there a way to write script to open a port such as SMTP/25
> > periodically for a certain amount of time, check for activity, wait till
> > free and then close it.
> >
> >This would be a cron'ed equivalent of bringing up Guarddog or some other
> >IPtables interface, enabling access, waiting a while and seeing no (or no
> >more) activity, bringing it up again and disabling access.
> >
> >
> >  
>
> use cron and iptables for it
>
> Allow new connection
> wait 10/15 mins
> forbid new connections but still allow established ones on port 25
>
> Am I wrong?

What I had in mind.

I use IPTables through a UI. The man pages show me nothing clear how to do the 
two function cited here. Please point me in the right direction :-)