/etc/hosts.equiv verses $HOME/.rhosts

[Joe Greco]

In comp.unix.wizards article <13650 at ulysses.att.com>, smb at ulysses.att.com (Steven Bellovin) wrote:
:In article <785 at venice.SEDD.TRW.COM>, waldorf at venice.SEDD.TRW.COM (Jerry Waldorf) writes:
:> Could some kind sole tell me why using $HOME/.rhosts 
:> is unsafe and why /etc/hosts.equiv is safe?  
:
:/etc/hosts.equiv represents the administrator's (presumably informed)
:decision to extend trust to certain other hosts, typically those also
:under the same person's control.  .rhosts files represent a user's
:decision to extend trust, often to a machine not worthy of it.

Neither is absolutely safe.  Then again, networks aren't safe.  You need to
be sure that your network is relatively secure, that your machines are
relatively secure, and that your host tables (or nameserver) are trustworthy,
to mention just a few...

Consider the following:

A person with a network monitoring program.  Just watch long enough and
snatch the password right off it.  Of course this ISN'T a problem with
.rhosts....

A person who breaks into a workstation, and changes the IP numbers to match
another machine.  Then crash the other machine.  Voila, suddenly what looks
like x.y.z.edu is actually a.y.z.edu... and you're at the mercy of the
person.

A person who can fiddle with the nameserver to produce false host names.  No
need to even change the IP number.  This is possibly the worst of the bunch.
Having (for legitimate reasons) done something similar to this on our local
network, I'm not too sure that there is anything to truly prevent someone
from doing this.

Long ago I decided it was all worthless: there's just no way to protect
against all possibilities.  I use .rhosts...

... Joe

-------------------------------------------------------------------------------
Joe Greco - University of Wisconsin, Milwaukee - Department of Mathematics
jgreco at archimedes.math.uwm.edu		USnail: Joe Greco
Voice: 414/321-6184				9905 W. Montana Ave.
Data:  414/321-9287 (Happy Hacker's BBS) 	West Allis, WI  53227-3329
ICBM:  43 05 20 N 87 53 10 W
#include <witty_and_humorous_saying.h>
Disclaimer: I don't speak for the Math Department, the University, or myself.