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From: Darren Reed (avalonCOOMBS.ANU.EDU.AU)
Date: Tue Mar 06 2001 - 16:58:58 CST

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    In some mail from Woody, sie said:
    >
    > Subject: Loopback and multi-homed routing flaw in TCP/IP stack.
    > Author: Woody <woodythebunker.net>
    >
    > We believe there to be a serious security flaw in the TCP/IP stack of
    > several Unix-like operating systems. Whilst being "known" behavior on
    > technical mailing lists, we feel that the implications of this
    > "feature" are unexpected. Furthermore, not all platforms behave in the
    > same way, which will obviously lead to invalid expectations.
    >
    > PLEASE NOTE: We have received a lot of replies to this advisory from
    > developers who have missed the point. Before you reply, please
    > read the advisory at least twice, to ensure you understand its
    > implications, and scope.

    No, I think you should have listened to people before you posted this.
    You clearly didn't, on a number of different fronts, including that for
    Solaris. Really, if you're going to post a security advisory and want
    to comment about Solaris you should at least go to the trouble of getting
    the Solaris8 source code, for a recent reference.

    The localhost issue where remote hosts can connect to localhost addresses
    on other boxes is an issue, yes, but the other...no.

    Much has been said about the strong vs weak ES model here so I'll not
    debate that any further. Suffice to say that it wasn't as unknown as
    you wanted to claim and people were happy with it. As you've been made
    aware, it's been known as a bug in NetBSD since 1995.

    The other part of your advisory is the argument that IP addresses on
    an interface should not be reachable, by default, through others because
    people bind things to particular interfaces for security reasons and
    that people would be surprised to find out it's not like that. Well,
    any admin who's setup something like that and gone on to not test his
    configuration is being careless. The expectation of implied filtering
    of packets is an illusion created by that person for themselves. I've
    not read anywhere that the behaviour is documented to be such. Your
    claim that this is wrong is just your opinion and typically security
    advisories are based on factual security flaws, not opinions. The
    security problem here is in people not testing "security" they think
    they have put in place.