From mike.gabriel@das-netzwerkteam.de Fri Jun 21 10:20:50 2013 Received: (at 241) by bugs.x2go.org; 21 Jun 2013 08:20:51 +0000 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on ymir.das-netzwerkteam.de X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=URIBL_BLOCKED autolearn=ham version=3.3.2 Received: from freya.das-netzwerkteam.de (freya.das-netzwerkteam.de [88.198.48.199]) by ymir (Postfix) with ESMTPS id C1A5C5DB2C for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:50 +0200 (CEST) Received: from grimnir.das-netzwerkteam.de (grimnir.das-netzwerkteam.de [78.46.204.98]) by freya.das-netzwerkteam.de (Postfix) with ESMTPS id 4D09B9B8 for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:50 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by grimnir.das-netzwerkteam.de (Postfix) with ESMTP id 237B83BB30 for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:50 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at grimnir.das-netzwerkteam.de Received: from grimnir.das-netzwerkteam.de ([127.0.0.1]) by localhost (grimnir.das-netzwerkteam.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8DXdNrw1nH+H for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:50 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by grimnir.das-netzwerkteam.de (Postfix) with ESMTP id EB3B83BC1A for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:49 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by grimnir.das-netzwerkteam.de (Postfix) with ESMTP id D3DAD3BB30 for <241@bugs.x2go.org>; Fri, 21 Jun 2013 10:20:49 +0200 (CEST) Received: by grimnir.das-netzwerkteam.de (Postfix, from userid 33) id 649693BBF5; Fri, 21 Jun 2013 10:20:49 +0200 (CEST) Received: from nocatv2.tng.de (nocatv2.tng.de [213.178.75.58]) by mail.das-netzwerkteam.de (Horde Framework) with HTTP; Fri, 21 Jun 2013 10:20:49 +0200 Message-ID: <20130621102049.28992mah70gw8xr5@mail.das-netzwerkteam.de> X-Priority: 3 (Normal) Date: Fri, 21 Jun 2013 10:20:49 +0200 From: Mike Gabriel To: Heinrich Schuchardt , 241@bugs.x2go.org Subject: Re: [X2Go-Dev] Bug#241: Changed host key cannot be updated References: <51BDB150.4040306@gmx.de> In-Reply-To: <51BDB150.4040306@gmx.de> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=_2hzrefx5vw0x"; protocol="application/pgp-signature"; micalg="pgp-sha1" Content-Transfer-Encoding: 7bit User-Agent: Internet Messaging Program (IMP) H3 (4.3.4) This message is in MIME format and has been PGP signed. --=_2hzrefx5vw0x Content-Type: text/plain; charset=UTF-8; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Heinrich, On So 16 Jun 2013 14:36:32 CEST Heinrich Schuchardt wrote: > Dear maintainer, > > from time to time the SSH key used for identification by a X2GO =20 > server may change. > > When trying to connect the server a pop up is shown: > > "Anmeldung fehlgeschlagen" > "Host-Key des Servers hat sich ge=C3=A4ndert Er lautet jetzt: > 00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 > Aus Sicherheitsgr=C3=BCnden wird die Verbindung abgebrochen" > > The user is left puzzled with what he should do next. > > There is no indication in which file there is a problem, e.g. > ~/.ssh/known_hosts > or > %APPDATA%\ssh\known_hosts > > There is no indication which entry in this file is corrupted. > > Deleting file known_hosts is a bad idea because it may contain the =20 > keys for dozens of validated servers. > > There are examples of more informative output, e.g. from command =20 > line program ssh: > > @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ > @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ > @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ > IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! > Someone could be eavesdropping on you right now (man-in-the-middle attack)= ! > It is also possible that a host key has just been changed. > The fingerprint for the RSA key sent by the remote host is > 00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00. > Please contact your system administrator. > Add correct host key in /home/user/.ssh/known_hosts to get rid of =20 > this message. > Offending RSA key in /home/user/.ssh/known_hosts:1 > RSA host key for 10.0.0.5 has changed and you have requested strict checki= ng. > Host key verification failed. > > Here I can identify the filename: /home/user/.ssh/known_hosts > and the line of the the entry: 1 > > Manual editing of known_hosts is now possible but not too good an =20 > idea because it is error prone. > > A good solution is what you see in PuTTY. A warning pop up is shown =20 > and you get the choice to update file known_hosts. > > Best regards The above surely is a good point to discuss first before implementing. Obviously, such a replace-host-key button would improve usability in =20 case host key changes occur. However, if someone captured DNS and replaced my X2Go server by an =20 agressive X2Go server, I (as developer) surely want to protect the =20 user from simply klicking ,,Yeah, ok man... replace that host key... =20 and can we go on then please...''. The SSH-unexperienced user (i.e. probably nearly everyone in the =20 windows world) will then just simply click ,,replace host key''. So, for me this kind of replace-host-key dialog should at least have a =20 double confirmation check dialog: Are you sure to replace... -> Are =20 you really sure???. That kind of thing. Heinrich: if you could come up with a patch for this issue, it would =20 surely speed up an inclusion of your requested feature. @all: comments, opinions on such a new feature? Mike --=20 DAS-NETZWERKTEAM mike gabriel, herweg 7, 24357 fleckeby fon: +49 (1520) 1976 148 GnuPG Key ID 0x25771B31 mail: mike.gabriel@das-netzwerkteam.de, http://das-netzwerkteam.de freeBusy: https://mail.das-netzwerkteam.de/freebusy/m.gabriel%40das-netzwerkteam.de.xf= b --=_2hzrefx5vw0x Content-Type: application/pgp-signature Content-Description: Digitale PGP-Unterschrift Content-Disposition: inline Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQIcBAABAgAGBQJRxAzhAAoJEJr0azAldxsx0YkP/ie4V6/plXQE4YBzKssxeLt0 z+ztVjUQDE9xGCQNvdLYpzcm/ojztUmJ53wKgu9wLn6uKcDer3acvSBhVduSSEqB i3DZLczmRUl2P0wk37P8AR5UZb+4m/sBN8sEDizPUAnUpLCTnlMhM4afbEbQ56C7 49i3oeJL9Uu5GG5c5O1UcY5l2NVMupeLDpac0OJNcsKbRXNxamIu90g6GhMeHEtd 2i5EkEqnboM3ntGEseP203utLrAEGqF+ez0ztkJx9VMNLntib145fQ6N8AUfnuI7 T3y7GPJq1wvjS/kIb7jtGMX/OrRRKHjr9rNnMyXrjVQ7bY54T432Ghz9P35rAeV4 iUL49BVj664Ij5OUM385wEr7PhoSEy7sd157bkNYMO2FlpFX0YYLwBUhO0hz7AKL VkJX0JoktYncQtviT6BybxaW21UtLwPJZBC8YVRgFVBG2Wll8A3axObmOVqkJZz3 t6/vemS3bd0CTyql+TuGim6tfZhnEt1FRDQYaEs1CvoLSeCVO8YaS1Qt0Qwf1slI FLGm66Y0yI+hqxeQU3Cb1iKk9q/4fWDvSx0MMQOpCEojr42jP03v2i8L3rRa2rV3 T+mq9L6b2WwwN3p56HcS79tnD7S9xeiru/6Zbc+6gk92ibPOjwY5eNQjQaNzLvfQ BYThWqbxuK+9K72l7HZW =xsB/ -----END PGP SIGNATURE----- --=_2hzrefx5vw0x--