Christopher Smith wrote:
Which aspect of Zeroconf are you referring to? I'm not doing anything
with link-local IP setup stuff (it wouldn't make sense), but can't see
where that stuff is any more of a security risk than using DHCP.

I know DHCP is a hole, but I hadn't thought about it in this context. I'll try to flesh out my understanding of the threat.

The threat profile I see with mDNS is as follows: hacker gets access to
the corporate LAN, and advertises himself as a providing a service (say
distcc). If clients of the service do not authenticate the providers,
then the hacker can potentially confuse clients to use their hacked
version of the service. Now, if you are serious about the security of
your source code, you have to be worried about IP spoofing and
man-in-the-middle attacks, which means either you believe you can
prevent such attacks (I'll bet against you, but you have at least
theoretically solved the problem), or your clients should already be
authenticating the service providers.

Right. And the hackers in question here might even be employees who have access to the LAN, but don't normally have access to the source code.

Of course, all this is moot if your source is ever written to a standard
network filesystem (say you have some NAS boxes), as a hacker could get
access to your source (and before the nasty C preprocessor has munged
it) simply by listening in on the traffic.

Another good hole; NFS = No File Security.


Sure, it'd be helpful if it had something like Kerberos to control
access to the directory, but truth be told, any hacker is going to be
able to discover what services are available on a network anyway. All
this is doing is making the services visible to everyone else.

I'm not worried about read access to the directory.


A few simple security measures should allow mDNS to be quite safe on a
corporate environment (simple things like looking for mDNS
responses/announcements which don't match expected service
configurations). distcc, on the otherhand, is a different matter.
Ultimately, if distcc is properly secured, using mDNS to autodiscover
distcc nodes shouldn't introduce security holes.

It's *advertizing* bogus distcc nodes that worries me.


For the record, have you considered just tunnelling distcc over ssh? It
would seem to be the trivial way to mitigate a number of distcc related
security concerns.

Yes. (See my post to the distcc mailing list.) My suspicion is that it adds too much startup overhead. Also, some distcc servers do not allow ssh logins for policy and/or technical reasons. - Dan

--
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