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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 suppo...

Anyone trying openssl 3 against openssh? -- Member - Liberal International This is doctor@@nl2k.ab.ca Ici doctor@@nl2k.ab.ca Yahweh, Queen & country!Never Satan President Republic!Beware AntiChrist rising! https://www.empire.kred/ROOTNK?t=94a1f39b Put more trust in nobility of character than in an oath. -Solon

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...

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 happene...

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.

...ommodate this situation. I have no way to upgrade the iDRAC nor to run with -ddd on it. -vvv output: OpenSSH_7.6p1, OpenSSL 1.1.0g-fips 2 Nov 2017 debug1: Reading configuration data /home/user/.ssh/config debug1: /home/user/.ssh/config line 1: Applying options for * debug3: kex names ok: [diffie-hellman-group1-sha1] debug1: Reading configuration data /etc/ssh/ssh_config debug3: /etc/ssh/ssh_config line 52: Including file /etc/ssh/ssh_config.d/05-redhat.conf depth 0 debug1: Reading configuration data /etc/ssh/ssh_config.d/05-redhat.conf debug3: /etc/ssh/ssh_config.d/05-redhat.conf line 2: Including...

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

https://bugzilla.mindrot.org/show_bug.cgi?id=2291 Bug ID: 2291 Summary: ssh -Q kex lists diffie-hellman-group1-sha1 twice Product: Portable OpenSSH Version: 6.7p1 Hardware: Other OS: Linux Status: NEW Severity: minor Priority: P5 Component: sftp-server Assignee: unassigned-bugs at mindrot.org...

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 > versions <= 0.64 so they...

...ersion OpenSSH_6.6 debug1: match: OpenSSH_6.6 pat OpenSSH_6.5*,OpenSSH_6.6* compat 0x14000000 debug1: Remote is NON-HPN aware debug2: fd 3 setting O_NONBLOCK debug1: Authenticating to 2x:22 as 'harry' debug2: compat_kex_proposal: original KEX proposal: curve25519-sha256 at libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c debug2: Compat: skipping algorithm "curve25519-sha256 at libssh.org" debug2: compat_kex_proposal: compa...

...; Nov 22 14:34:03 myhostname sshd[3905]: debug3: send packet: type 20 [preauth] > > Nov 22 14:34:03 myhostname sshd[3905]: debug1: SSH2_MSG_KEXINIT sent [preauth] > > > > Can you help? > > That ~13-year-old version of dbclient only has weak key exchange methods - > diffie-hellman-group1-sha1, "OpenSSH supports this method, but does not > enable it by default because is weak and within theoretical range of the > so-called Logjam attack" and diffie-hellman-group1-dss, disabled by default > in OpenSSH in 2015. > > Also only weak CBC-mode ciphers, disab...

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: > > Y...

...Version: 8.2p1 Hardware: All OS: All Status: NEW Severity: major Priority: P5 Component: ssh Assignee: unassigned-bugs at mindrot.org Reporter: nneul at neulinger.org I understand the desire to remove diffie-hellman-group14-sha1 for example from the default offers - and agree completely with that. This bug is NOT about the removal/default changes. Somewhere between 7.6p1 and 8.2p1 the ability to add the deprecated algorithms back in via config has broken. IT DOES WORK on command line. It's only in the co...

...not using the patch format and I also apologize if we are not supposed to post patch-like info. Also.. if you do try to recompile.. you might need to change your Makefiles. All of these files are in /usr/src/ssh/ TO REMOVE GROUP1 and GROUP14 IN myproposal.h #define KEX_DEFAULT_KEX "diffie-hellman-group-exchange-sha256," \ "diffie-hellman-group-exchange-sha1," \ "diffie-hellman-group14-sha1," \ "diffie-hellman-group1-sha1" CHANGE TO #define KEX_DEFAULT_KEX "diffie-hellman-group-exchange-sha256," \ "diffie-hellman-group-exchange-s...

...n string SSH-2.0-OpenSSH_6.7 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6 debug1: match: OpenSSH_6.6 pat OpenSSH_6.5*,OpenSSH_6.6* compat 0x14000000 debug2: fd 3 setting O_NONBLOCK debug2: compat_kex_proposal: original KEX proposal: curve25519-sha256 at libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 debug2: Compat: skipping algorithm "curve25519-sha256 at libssh.org" debug2: compat_kex_proposal: compat KEX proposal: diffie-hellman-group-exchange-sha256,diffie-hellman-group1...

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 zip.com.au Re...

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

...ve25519-sha256 -- [info] default key exchange since OpenSSH 6.4 (kex) curve25519-sha256 at libssh.org -- [info] available since OpenSSH 6.4, Dropbear SSH 2013.62 (kex) curve25519-sha256 at libssh.org -- [info] default key exchange since OpenSSH 6.4 (kex) diffie-hellman-group16-sha512 -- [info] available since OpenSSH 7.3, Dropbear SSH 2016.73 (kex) diffie-hellman-group18-sha512 -- [info] available since OpenSSH 7.3 (kex) diffie-hellman-group-exchange-sha256 (3072-bit) -- [info] available since OpenSSH 4.4 (kex) diffie-hellman-group-exchange-sha256...

...the algorithm negotiation of the transport layer has a bug, it does not follow the specification of draft-ietf-secsh-transport-24, page 19, where the behaviour of first_kex_packet_follows is specified. I've got an ssh client that sends an SSH_MSG_KEXINIT message and specifies only 'diffie-hellman-group1-sha1' as key exchange algorithm. It sets first_kex_packet_follows to true, and immediately sends the SSH_MSG_KEXDH_INIT message. The ssh server (openssh-3.9p1) specifies three key exchange algorithms in its SSH_MSG_KEXINIT message: 'diffie-hellman-group-exchange-sha1,diffie-hellman-g...

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* WinSCP_release_5.6* WinSCP_rel...