Date: Mon, 22 Nov 1999 01:02:31 -0500 (EST) From: Robert Watson <robert@cyrus.watson.org> To: Dug Song <dugsong@monkey.org> Cc: Tomaz Borstnar <tomaz.borstnar@over.net>, freebsd-security@freebsd.org Subject: Re: OpenSSH & AllowHosts Message-ID: <Pine.BSF.3.96.991122005937.27394A-100000@fledge.watson.org> In-Reply-To: <Pine.BSO.4.10.9911211216430.4499-100000@funky.monkey.org>
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On Sun, 21 Nov 1999, Dug Song wrote: > > I know it can be done via packet filtering, but 100% compatibility > > with usual ssh would be nice. Anyone knows if this will be added? > > OpenSSH intentionally deviates from the original SSH in many ways - see > > http://violet.ibs.com.au/openssh/files/UPGRADING > I've noticed that OpenSSH also seems to handle hostnames in ssh_known_hosts differently--I have a fairly extensive ssh_known_hosts file distributed across my machines to account for all the hosts I regularly connect to. I found that the new OpenSSH ignores the hostname-based entries and adds new IP-based entries automatically, with minimal warning. Is it doing all lookups based on IP and adding the key as a new host key, or is it copying the old entry to a new entry with new name? The first would seem to be fairly insecure (as the warning is not very loud and doesn't request confirmation); the second is not documented in the UPGRADING file and a little alarming :-). Any clarification here would be much appreciated--if it is absorbing new host keys without asking for confirmation, even though host keys are already present with a by-name lookup, I'm not sure I like the behavior--names are more likely to remain consistent in the world of NATs, dynamic IPs with DNS update, etc. Robert N M Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: AF B5 5F FF A6 4A 79 37 ED 5F 55 E9 58 04 6A B1 TIS Labs at Network Associates, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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