similar to: Support for "ssh-rsa-sha256" and "ssh-dss-sha256" ?

On Fri, May 22, 2015 at 12:27:01, Darren Tucker <dtucker at zip.com.au> wrote: > Note that PuTTY does do Diffie-Hellman Group Exchange, but until very > recently (ie after their 0.64 release) they didn't do the one that was > actually standardized in RFC4419. OpenSSH recently removed support for > that non-standard one and as a result we don't offer DHGEX to PuTTY >

Also, how are default moduli shipped with OpenSSH for use in diffie-hellman-group-exchange-sha1/sha256 chosen? Are they chosen randomly by developers or are they chosen for security properties? If they are random, why not use moduli from RFC 7919 instead, like Mozilla recommends? On Fri, Feb 15, 2019 at 3:48 AM Mark D. Baushke <mdb at juniper.net> wrote: > > Yegor Ievlev <koops1997

I ask because the removal of diffie-hellman-group-exchange-sha1 happened accidently in 7.8 due to a mistake in a change to readconf.c. I noticed this and filed a bug about it along with a patch to fix readconf.c to use KEX_CLIENT_* like it used to: https://github.com/openssh/openssh-portable/commit/1b9dd4aa https://bugzilla.mindrot.org/show_bug.cgi?id=2967 Its clear the removal was unintentional

https://bugzilla.mindrot.org/show_bug.cgi?id=2302 --- Comment #13 from Darren Tucker <dtucker at zip.com.au> --- (In reply to Christoph Anton Mitterer from comment #10) [...] > Even though an attacker cannot (AFAIU??) for a connection to > downgrade to the weaker groups, The server's DH-GEX exchange hash includes the DH group sizes it received from the client. If these are

Can we disable diffie-hellman-group14-sha1 too? On Thu, Feb 14, 2019 at 10:23 PM Mark D. Baushke <mdb at juniper.net> wrote: > > Hi John, > > The short answer is YES. > > Jon DeVree <nuxi at vault24.org> writes: > > > I ask because the removal of diffie-hellman-group-exchange-sha1 happened > > accidently in 7.8 due to a mistake in a change to

I'm not nearly knowledgeable enough in crypto to fully understand your answer, but I will try. I wonder why moduli are not automatically generated the first time sshd is started though. That would make much more sense than shipping a default moduli file but also asking everyone to replace it with their own. On Fri, Feb 15, 2019 at 5:50 AM Mark D. Baushke <mdb at juniper.net> wrote: >

Hi, You will be aware of https://weakdh.org/ by now, I presume; the take-home seems to be that 1024-bit DH primes might well be too weak. I'm wondering what (if anything!) you propose to do about this issue, and what Debian might do for our users? openssh already prefers ECDH, which must reduce the impact somewhat, although the main Windows client (PuTTY) doesn't support ECDH yet. But

Greetings, Given the weakness with Diffie-Hellman modp groups less than 2048, is it time to bump the suggested 1024 bit minimum value from the RFC 4419 to a more current 2048 value for OpenSSH 7.0? If so, should this be just a compile-time change, or should there be a new client and server runtime option? Thanks, -- Mark

https://bugzilla.mindrot.org/show_bug.cgi?id=2515 Bug ID: 2515 Summary: Implement diffie-hellman-group{14,15,16)-sha256 Product: Portable OpenSSH Version: -current Hardware: All OS: All Status: ASSIGNED Severity: enhancement Priority: P3 Component: ssh Assignee: dtucker at

https://bugzilla.mindrot.org/show_bug.cgi?id=2302 Bug ID: 2302 Summary: ssh (and sshd) should not fall back to deselected KEX algos Product: Portable OpenSSH Version: 6.7p1 Hardware: All OS: All Status: NEW Severity: security Priority: P5 Component: ssh

https://bugzilla.mindrot.org/show_bug.cgi?id=2302 Bug ID: 2302 Summary: ssh (and sshd) should not fall back to deselected KEX algos Product: Portable OpenSSH Version: 6.7p1 Hardware: All OS: All Status: NEW Severity: security Priority: P5 Component: ssh

I apologize up-front if this is the wrong list for this question. Can OpenSSH be made to work with the MODP Groups in RFC 5114? ?The RFC itself makes a comment in section 3.4 that mentions that RFC 4419 extended the original SSH model to allow Diffie-Hellman parameters to be transmitted as part of the key exchange messages, but I'm not clear how that works with OpenSSH's moduli file. Do

https://bugzilla.mindrot.org/show_bug.cgi?id=2109 Bug ID: 2109 Summary: Add support for ssh-rsa-sha256 and ssh-dsa-sha256 public key algorithms Product: Portable OpenSSH Version: 6.2p1 Hardware: All OS: FreeBSD Status: NEW Severity: enhancement Priority: P5

Hi, I'm interested in requiring a minimum of 3072-bit DH moduli when using the "diffie-hellman-group-exchange-sha256" kex, so I edited my /etc/ssh/moduli file such that only 3071+ moduli are left. However, when clients ask for a max of 2048-bit moduli, they actually get one (!). I poked around and found that a fallback mechanism exists (dh.c:185), which returns back the

Hello, On Sun, Sep 22, 2024 at 10:15?AM Kurt Fitzner via openssh-unix-dev <openssh-unix-dev at mindrot.org> wrote: > > I would like to advocate for: > > - Change behaviour of the server to allow server operators to set the > minimum modulus group size allowable for a connection using > diffie-hellman-group-exchange-sha256 > Whether this is by having the server refuse

Il giorno gio 22 nov 2018 alle ore 21:24 Stuart Henderson <stu at spacehopper.org> ha scritto: > > On 2018/11/22 19:55, owl700 at gmail.com wrote: > > Hi, I have compatibility issues with the latest version of > > openssh-server and an old dropbear client, the dopbear client stops at > > preauth > > > > ov 22 14:34:03 myhostname sshd[3905]: debug1: Client

https://bugzilla.mindrot.org/show_bug.cgi?id=2209 Bug ID: 2209 Summary: Problem logging into Cisco devices under 6.5p1 (kexgexc.c) Product: Portable OpenSSH Version: 6.5p1 Hardware: amd64 OS: FreeBSD Status: NEW Severity: normal Priority: P5 Component: ssh

Hello all, I have recently had cause to dig a little into the specifics of how diffie-hellman-group-exchange-sha256 group sizes work. The belief in the wild, perpetuated by multiple sources of logjam mediation papers and also Andras Stribnik's very influential piece "Secure Secure Shell", is that server operators can force the use of a minimum group size by removing moduli

Hi, OpenSSH 6.5 is almost ready for release, so we would appreciate testing on as many platforms and systems as possible. This release contains some substantial new features and a number of bugfixes. Snapshot releases for portable OpenSSH are available from http://www.mindrot.org/openssh_snap/ The OpenBSD version is available in CVS HEAD: http://www.openbsd.org/anoncvs.html Portable OpenSSH is

Functionality request for supporting Digital Signatures for RSA and DSS Public Key Algorithms in alignment with NIST SP800-131A. I assume this has been asked before, but I could not find in the archives. Support of "ssh-rsa-sha256" and "ssh-dss-sha256" public key algorithms for OpenSSH? I know Suite B Algorithms and x509 SSH Extension Algorithms are supported, but not a