Re: Script to temporarily "open" port

[Laurent CARON <lcaron@apartia.fr>]

David Baron 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?