similar to: Can we disable diffie-hellman-group14-sha1 by default?

e.g. can we make it throw warnings etc. rsa-sha2-256 and rsa-sha2-512 are fine, they use PSS. On Sun, Jan 20, 2019 at 1:55 AM Yegor Ievlev <koops1997 at gmail.com> wrote: > > Also can we do anything with ssh-rsa? It uses both SHA-1 and > deprecated PKCS#1 padding. If it's used to sign certificates, there's > no additional protection of SHA-2 hashing before SHA-1

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 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

I don't think there is any point to generate so many moduli. Actually, 3 moduli of sizes 2048, 3072 and 4096 seem like a sane choice. On Fri, Feb 15, 2019 at 7:58 AM Darren Tucker <dtucker at dtucker.net> wrote: > > On Fri, 15 Feb 2019 at 14:22, Yegor Ievlev <koops1997 at gmail.com> wrote: > > I'm not nearly knowledgeable enough in crypto to fully understand your

That doesn't seem to be the case. See https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57pt1r4.pdf (5.6.1 Comparable Algorithm Strengths) On Fri, Feb 15, 2019 at 8:28 AM Darren Tucker <dtucker at dtucker.net> wrote: > > On Fri, 15 Feb 2019 at 16:00, Yegor Ievlev <koops1997 at gmail.com> wrote: > > I don't think there is any point to generate so

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: >

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=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

The defaults for HostKeyAlgorithms option are: ecdsa-sha2-nistp256-cert-v01 at openssh.com, ecdsa-sha2-nistp384-cert-v01 at openssh.com, ecdsa-sha2-nistp521-cert-v01 at openssh.com, ssh-ed25519-cert-v01 at openssh.com, ssh-rsa-cert-v01 at openssh.com, ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, ssh-ed25519,ssh-rsa Why does OpenSSH prefer older and less secure

https://bugzilla.mindrot.org/show_bug.cgi?id=2729 Bug ID: 2729 Summary: Can connect with MAC hmac-sha1 even though it's not configured on the server Product: Portable OpenSSH Version: 7.5p1 Hardware: All OS: Linux Status: NEW Severity: security Priority: P5

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

there are more implications to changing key algorithms than KEX algorithms. If a change is made to the specification, then it might invalidate all the keys that are out there, this isn't the case with any other negotiated algorithm, On Sun, 27 May 2018, Yegor Ievlev wrote: > I don't think we should wait for a RFC in order to use stronger > crypto. We already prefer Curve25519 for

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 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

That's not a very good source, since it's only available to one person. On Fri, May 25, 2018 at 7:12 AM, Peter Moody <mindrot at hda3.com> wrote: > On Thu, May 24, 2018 at 9:09 PM, Yegor Ievlev <koops1997 at gmail.com> wrote: >> How can I revoke one SSH certificate without having to replace the >> root certificate and all certificates signed by it? > >

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

Get the following error: root at x065:[/data/prj/openbsd/openssh/openssh-7.7p1/openbsd-compat]make ??????? xlc_r -I/opt/include -O2 -qmaxmem=-1 -qarch=pwr5 -q64 -I. -I.. -I../../src/openssh-7.7p1/openbsd-compat -I../../src/openssh-7.7p1/openbsd-compat/.. -I/opt/include -DHAVE_CONFIG_H -c ../../src/openssh-7.7p1/openbsd-compat/strndup.c

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"

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