[asterisk-users] OT: fail2ban, spam and mail servers

[Hans Witvliet]

On Tue, 2010-07-13 at 06:53 -0400, covici at ccs.covici.com wrote:
> What you can do -- I don't know about nomad, but can you make them use
> authentication?
> 
> Randy R <randulo2008 at gmail.com> wrote:
> 
> > On Tue, Jul 13, 2010 at 12:29 PM,  <covici at ccs.covici.com> wrote:
> > > What I do, is only open port 25 to the list of ips of the spam filtering
> > > service -- I use an iptables script called rc.firewall which I found
> > > several years ago which works well and has a nice syntax for this and I
> > > get no direct spam, I get some which gets by the filters.
> > 
> > Hi John,
> > 
> > I'd like to do that, but there are nomad users who might be anywhere
> > in the world. True maybe I could ask them to use port 587 and then
> > allow ONLY the service IPs access to port 25.
> > 
> > /r
> > 

Just wondering,
Most spammers or cases of joe-jobs originate from an other URL then they
claim to come from. 

Can this not be dealt with using certificates?
Something like for nomads, only accepting signed messages...

hw