Wow, this should provoke a discussion other than stupid "hacker list" or "root".
I hope we can keep the flamage down, since I think this is a serious issue.
But what a provocative thread title!
I have seen the model of "hard surface, gooey interior" explicitly advocated.
I suspect reliance on this model, rather than laziness is the cause.
Who can say that nobody (summer interns included) inside their domain
might produce as big a risk as that cretin at some anonymous site?
And, does everybody inside trust everybody else?
I know the idea of bringing the warring parties together in an organization
is practiced (maybe not as much as here :-) in many places.
The model of gooey interior is also sometimes justified by the allocation
of resources. Some organizations have a small set of Unix (say - no flames)
administrators for the whole place. Good security means putting your resources
where they do the most good.
However, many of the scary things that could enter your site from the Internet
are now inside the semantics of novel applications: Mosaic, Gopher, what else?
Detecting and blocking these at a transit point is getting harder.
And if some subset of your users is sharp enough (admit it there are some :-)
to use the clever features of Sendmail where programs are recipients in a
safe way, must you "non-deliver" mail to them at the firewall?
Murphy says they will be widely distributed in your internal address space.
Do you want to give even a toe-hold to the idea that some people's computers
are save "outside the firewall"? Have you no obligation to protect them?
And another however, if some clever person (are you sure there aren't ANY)
becomes convinced that the limitations of the firewall are onerous,
it is remarkably easy for him/her to open a path to the outside you don't
even know about. Dare you leave the inside gooey now that you have realized
this is possible?
The nature of the firewall, what should it protect, and what should be
protected at every computer is a topic we could discuss profitably.
Cheswick and Bellovin (if you haven't read it, consider unsubscribing)
make their case for trusting nobody but yourself (the firewall person).
Rational discussion of other views, and the technical configurations that
correspond to them, would be good for this list.