[Asterisk-Users] hook into authentication

trixter aka Bret McDanel
Sun, 28 May 2006 22:12:34 -0000

On Sun, 2006-05-28 at 23:41 -0400, Steve Totaro wrote:
> Henry J. Cobb wrote:
> >> to increase the security for remote extensions I would like to
limit a
> >> sip-peer to a specific MAC address. Is it possible to "hook
into" the
> >> authentication mechanism in asterisk and allow/deny incoming
> >> registrations?
> >>
> >
> > This would be only mildly useful on the same subnet and completely
useless
> > over the internet.
> >
> > -HJC
> >
> >
> I think it would work just fine over the internet using a bridged VPN.

even on a local network this can be forged.  If you cant control the
device that sends this information it is user supplied data, even over a
vpn (which uses a virtual interface not the physical one).  It has the
same value as any user supplied data - other than perhaps its additional
data which makes guessing slightly harder.

TLS might be a better way to go since it would require a certificate
that you can control the issuance of, but that certificate can be stolen
and the remote end point would need to support the same scheme that you
use (fortunately there are standards that make this easier with some
devices but most dont implement this).

A vpn would provide security in that it would make it harder for someone
to eavesdrop on the auth and attempt to derrive the password, however
there is overhead associated with that.  At least 1 IP packet per real
packet (sometimes more) on the network side, and the crypto parts on the
cpu side.  For the server you would want to have a hardware based crypto
card to deal with the VPN connections...


--
Trixter http://www.0xdecafbad.com     Bret McDanel
Belfast IE +44 28 9099 6461    DE +49 801 777 555 3402
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http://www.sacaug.org/ Sacramento Asterisk Users Group

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