Re: Disable ZeroConf: how to ?
On Fri, Mar 04, 2011 at 04:09:44PM +0100, Olaf van der Spek wrote:
> On Fri, Mar 4, 2011 at 3:59 PM, Klaus Ethgen <Klaus@ethgen.de> wrote:
> > In ancient times debian was packaged the way that the administrator only
> > installed the daemons that he needed. Today many daemons gets installed
> > by dependencies and gets started without any need.
> > If you want to change debian to be ubuntu it would be the time to look
> > for another distribution that can be used on servers. (unfortunately I
> > do not know an alternative.)
> Actually "Ubuntu ships with no open ports on public interfaces" (by default).
[~]# netstat -ap|grep avahi
udp 0 0 *:mdns *:* 1622/avahi-daemon:
udp 0 0 *:45282 *:* 1622/avahi-daemon:
udp6 0 0 [::]:mdns [::]:* 1622/avahi-daemon:
udp6 0 0 [::]:58036 [::]:* 1622/avahi-daemon:
I admit I didn't notice this before, as I would never expect a _client_
system to have some crap listening by default. And it is world-reachable
-- am I supposed to ensure the top s1kr3t address
2001:6a0:118:0:22cf:30ff:fec3:d4b7 never leaks out? (oops...)
And why does it open this security hole? To make it slightly easier to
configure link-local instant messages. Who exactly is going to need that
these days? The times of local networks disconnected from the world are
mostly over. You have some non-networked machines here and there, but if
there's a network of some kind, it almost always is globally connected.
These few places that do have airwalled networks definitely don't want to
run link-local chat...
So, any gain is infinitessimally small, and the risk is real. Even daemons
coded by most security-minded people that have seen a lot of review do have
exploitable holes once in a while, so I expect Avahi to fare no better.
Like, for example, #614785.
1KB // Microsoft corollary to Hanlon's razor:
// Never attribute to stupidity what can be
// adequately explained by malice.