similar to: Diffie Hellman key exchange algorithms

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

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

I'm not sure if collision resistance is required for DH key derivation, but generally, SHA-1 is on its way out. If it's possible (if there's not a very large percentage of servers that do not support anything newer), it should be disabled.

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

Hello, I'd like to inform you that the next release of WinSCP SFTP client (version 5.7.5) will support Diffie-Hellman group exchange as specified by RFC 4419. http://winscp.net/tracker/show_bug.cgi?id=1345 So I'd like to ask you to kindly update the check in compat_datafellows() to WinSCP_release_4* WinSCP_release_5.0* WinSCP_release_5.1* WinSCP_release_5.2* WinSCP_release_5.5*

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

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 >

Currently, dovecot generates two primes for Diffie-Hellman key exchanges: a 512-bit one and a 1024-bit one. In light of recent events, I think it would be wise to add support for 2048-bit primes as well, or even better, add a configuration option that lets the user select a file (or files) containing the DH parameters In recent years, there has been increased interest in DH especially in its

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

> Can this be addressed in ssh_config/sshd_config with the KexAlgorithms setting? weakdh.org/sysadmin.html recommends adding: KexAlgorithms curve25519-sha256 at libssh.org But this thread makes it sound as if it's not necessary. Can anyone confirm? Personally I'm on openssh-6.7. - Grant > You will be aware of https://weakdh.org/ by now, I presume; the take-home seems to be

On 09/22/2017 06:55 PM, Tim Broberg wrote: > Do I understand correctly, that you find the security of group 14 unacceptable and yet you left it enabled? In the end, I'm trying to ensure a minimum equivalent of 128-bits of security. Group14 is 2048-bits, which roughly translates to 112-bits. [1] To this end, I disabled the "diffie-hellman-group14-sha1" and

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

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

On 09/24/2017 12:21 AM, Mark D. Baushke wrote: > I suggest you upgrade to a more recent edition of the OpenSSH software. > The most recent release is OpenSSH 7.5 and OpenSSH 7.6 will be released > very soon. This problem is in v7.5 and v7.6. See dh.c:436. > OpenSSH 6.6 was first released on October 6, 2014. I brought up v6.6 to give an example that older clients wouldn't be

Trying to connect to a Dell iDRAC 6. The iDRAC reports it is running OpenSSH 5.2. From Fedora Linux 20 with OpenSSH 6.4p1, connections succeed. From Fedora Linux 23 with OpenSSH 7.2p2, connections succeed. From Fedora Linux 27 with OpenSSH 7.6p1, connections fail prior to prompting for a password. The message is, "Received disconnect from (IP address) port 22:11: Logged out." Trying

Hello, I have some users that connect to a server with their DSA key that is of type ssh-dss. I'm migrating (installing as new) the server where they connect to CentOS 8 + updates. I was not able to connect with the keys to this new server even after having added, as found in several internet pages, this directive at the end of /etc/ssh/sshd_config of the CentOS 8 server: # Accept also DSA

https://bugzilla.mindrot.org/show_bug.cgi?id=3184 Bug ID: 3184 Summary: Unable to add deprecated KexAlgorithms back for host via config file Product: Portable OpenSSH Version: 8.2p1 Hardware: All OS: All Status: NEW Severity: major Priority: P5 Component: ssh

Hello, I'm looking for your insight about the log below. We have an SFTP server (IBM Sterling File Gateway) and we're connecting from an OpenSSH SFTP client but something fails during KEX. Complete client-side debug output is below, but I believe the relevant part is: debug1: kex: server->client cipher: aes192-cbc MAC: hmac-sha1 compression: none debug1: kex: client->server