similar to: sshd key exchange security

> 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

It should be compatible with the original patch. However I think that the shared secret should be encoded as a string, too. What does libssh do? > Am 02.11.2013 um 05:46 schrieb Damien Miller <djm at mindrot.org>: > >> On Fri, 1 Nov 2013, Markus Friedl wrote: >> >> Here are three versions (patch against openbsd cvs) >> >> 1) repace nacl w/libsodium,

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

Once upon a time, Alice Wonder <alice at domblogger.net> said: > They recommend setting the following: > > KexAlgorithms curve25519-sha256 at libssh.org > > I don't even see that directive in my sshd config to set it, I > suppose it may be one that is manually added when needed but I want > to verify it actually means something in CentOS 7 ssh. > > Also

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

Hi, In a recent security review some systems I manage were flagged due to supporting "weak" ciphers, specifically the ones listed below. So first question is are people generally modifying the list of ciphers supported by the ssh client and sshd? On CentOS 6 currently it looks like if I remove all the ciphers they are concerned about then I am left with Ciphers

Dear OpenSSH developers, I've worked this week on an alternative key exchange mechanism, in reaction to the whole NSA leaks and claims over cryptographic backdoors and/or cracking advances. The key exchange is in my opinion the most critical defense against passive eavesdropping attacks. I believe Curve25519 from DJB can give users a secure alternative to classical Diffie-Hellman (with fixed

Here are three versions (patch against openbsd cvs) 1) repace nacl w/libsodium, so i could test 2) curve25519-donna 3) Matthew's public domain reference implementation. i'd vote for #3 -------------- next part -------------- Am 30.10.2013 um 07:27 schrieb Damien Miller <djm at mindrot.org>: > On Tue, 24 Sep 2013, Aris Adamantiadis wrote: > >> Dear OpenSSH

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

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"

Am 02.11.2013 um 11:38 schrieb Aris Adamantiadis <aris at 0xbadc0de.be>: > RFC4251 describes mpint to be multi-size and with positive values having > MSB clear, so it's clearly incompatible with raw string. > > Since you both agreed on the curve25519 implementation to use, I'll work > today on Markus' patch to make the changes Damien wanted. What do you want to

Darren Tucker <dtucker at zip.com.au> writes: > On Tue, Nov 8, 2016 at 2:43 PM, Harry Putnam <reader at newsguy.com> wrote: >> 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 >>>> >>>>

I have developed a compact at the same time high performance library for curve25519/ed25519 and I have placed it in the public domain. It support DH key exchange as well as ed25519 keygen, sign and verify. The implementation is constant-time, supports blinding, bulk-verify and more. The library is available as portable-C as well as ASM for Intel-x64 CPUs. It outperforms curve25519-donna by a

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

https://bugzilla.mindrot.org/show_bug.cgi?id=2233 Bug ID: 2233 Summary: curve25519-sha256 at libssh.org Signature Failures When 'sshd' Used with Dropbear Clients Product: Portable OpenSSH Version: 6.6p1 Hardware: All OS: All Status: NEW Severity: major Priority: P5

Hi, So I screwed up when writing the support for the curve25519 KEX method that doesn't depend on OpenSSL's BIGNUM type - a bug in my code left leading zero bytes where they should have been skipped. The impact of this is that OpenSSH 6.5 and 6.6 will fail during key exchange with a peer that implements curve25519-sha256 at libssh.org properly about 0.2% of the time (one in every 512ish

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

See attached: (1) patch against 7.9p1, tested with openssl 1.1.0j and openssl 1.1.1a on linux/i386; passes regression test and connects to unpatched sshd without problems; I hacked a bit regress/unittests/kex, and benchmarked do_kex_with_key("curve25519-sha256 at libssh.org", KEY_ED25519, 256); Before: 0.3295s per call After: 0.2183s per call That is, 50% speedup; assuming

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

Am 19.10.2016 um 00:58 schrieb Gordon Messmer <gordon.messmer at gmail.com>: > On 10/18/2016 03:28 PM, Clint Dilks wrote: >> So first >> question is are people generally modifying the list of ciphers supported by >> the ssh client and sshd? > > I suspect that "generally" people are not. I do, because I can, and so that I can offer at least some advice