similar to: [Bug 2515] New: Implement diffie-hellman-group{14,15,16)-sha256

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

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.

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

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

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

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 protocol version 2.0; client software version dropbear_0.46 Nov 22 14:34:03 myhostname sshd[3905]: debug1: no match: dropbear_0.46 Nov 22 14:34:03 myhostname sshd[3905]: debug1: Local version string

A few questions regarding the OpenSSH support for the Diffie Hellman key exchange algorithms: (1) Are the diffie-hellman-group-exchange-sha256", "diffie-hellman-group-exchange-sha1" , "diffie-hellman-group14-sha1" "diffie-hellman-group1-sha1" (as defined in RFCs 4253 and RFC 4419) the complete list of key exchange algorithms supported by OpenSSH? (2) Is there a

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

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

I referred to the fact that there is no value for 4096-bit groups at all. For higher strengths than 128 bits one should probably not use non-EC crypto at all, as the document suggests. On Fri, Feb 15, 2019 at 9:19 AM Darren Tucker <dtucker at dtucker.net> wrote: > > On Fri, 15 Feb 2019 at 16:45, Yegor Ievlev <koops1997 at gmail.com> wrote: > > That doesn't seem to be

On 25.01.24 14:09, Kaushal Shriyan wrote: > I am running the below servers on Red Hat Enterprise Linux release 8.7 > How do I enable strong KexAlgorithms, Ciphers and MACs On RHEL 8, you need to be aware that there are "crypto policies" modifying sshd's behaviour, and it would likely be the *preferred* method to inject your intended config changes *there* (unless they

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*

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

Thanks Joseph, Aki, but something missing from upgrade document, where does the dh param file go? I located ssl-parameters.dat so I will put it there. Quoting Joseph Tam <jtam.home at gmail.com>: > On Fri, 22 Jun 2018, Joseph Tam wrote: > >> However, recent advances make this condition obsolete [*] and not >> really safer, so a much faster way to generate a DH key is

hi sorry if question was asked already. Was reading https://wiki2.dovecot.org/Upgrading/2.3 first I'm confused on diffie hellman parameters file. I never set up ssl-parameters.dat before (should i have? do I have one that was automatically made for me by dovecot?) Do I need to make a fresh dh.pem? The upgrade doc tells how to convert ssl-parameters.dat but how to make a new one? other

Hi Kaushal, I maintain a set of SSH hardening guides for various platforms, including RHEL 8. You can find them here: https://ssh-audit.com/hardening_guides.html - Joe -- Joseph S. Testa II Founder & Principal Security Consultant Positron Security On Thu, 2024-01-25 at 18:39 +0530, Kaushal Shriyan wrote: > Hi, > > I am running the below servers on Red Hat Enterprise

https://bugzilla.mindrot.org/show_bug.cgi?id=3522 Bug ID: 3522 Summary: Crash with "free(): double free detected" with old clients Product: Portable OpenSSH Version: 9.1p1 Hardware: amd64 OS: Linux Status: NEW Severity: minor Priority: P5 Component: sshd

Darren Tucker <dtucker at zip.com.au> writes: > On Tue, Nov 8, 2016 at 1:02 PM, Harry Putnam <reader at newsguy.com> wrote: > [...] >> gv harry> ssh -vv 2x >> >> OpenSSH_7.3p1-hpn14v11, OpenSSL 1.0.2j 26 Sep 2016 > > this is a third-party modified version of OpenSSH. Can you reproduce > the problem with a stock OpenSSH from the source from

On 30/06/2023 09:56, Damien Miller wrote: > It's very hard to figure out what is happening here without a debug log. > > You can get one by stopping the listening sshd and running it manually > in debug mode, e.g. "/usr/sbin/sshd -ddd" Or starting one in debug mode on a different port, e.g. "-p99 -ddd"