similar to: An Analysis of the DHEat DoS Against SSH in Cloud Environments

In the upcoming v9.8 release notes I see "the server will now block client addresses that repeatedly fail authentication, repeatedly connect without ever completing authentication or that crash the server." Has this new PerSourcePenalties config directive been tested against the DHEat attack? - Joe On Thu, 2024-04-25 at 18:09 -0400, Joseph S. Testa II wrote: > A few days ago, I

On Tue, 18 Jun 2024, Joseph S. Testa II wrote: > In the upcoming v9.8 release notes I see "the server will now block > client addresses that repeatedly fail authentication, repeatedly > connect without ever completing authentication or that crash the > server." Has this new PerSourcePenalties config directive been tested > against the DHEat attack? Not explicitly but

On Wed, 2024-06-19 at 16:11 -0400, Joseph S. Testa II wrote: > I suppose in the next few days, I'll try reproducing my original > steps > with the new version and see what happens. I managed to do some limited testing with a local VM, and the results are... interesting. I installed openssh-SNAP-20240626.tar.gz on a fresh and fully-updated Ubuntu Linux 24.04 LTS VM with 1 vCPU.

On Wed, 2024-06-19 at 09:19 -0400, chris wrote: > real world example (current snapshot of portable on linux v. dheater) Thanks for this. However, much more extensive testing would be needed to show it is a complete solution. In my original research article, I used CPU idle time as the main metric. Also, I showed that very low- latency network links could bypass the existing countermeasures.

On Wed, Jun 19, 2024 at 02:10:30PM +1000, Damien Miller wrote: > On Tue, 18 Jun 2024, Joseph S. Testa II wrote: > > > In the upcoming v9.8 release notes I see "the server will now block > > client addresses that repeatedly fail authentication, repeatedly > > connect without ever completing authentication or that crash the > > server." Has this new

On 6/19/24 4:11 PM, Joseph S. Testa II wrote: > On Wed, 2024-06-19 at 09:19 -0400, chris wrote: >> real world example (current snapshot of portable on linux v. dheater) > > Thanks for this. However, much more extensive testing would be needed > to show it is a complete solution. In my original research article, I > used CPU idle time as the main metric. Also, I showed that

On Tue, 25 Jun 2024, Joseph S. Testa II wrote: >the way down to 6%! Additionally, I noticed that the systemd-journal You should test without that thing as well. It?s reportedly a known bottleneck (someone on, I think, IRC said that regarding a different problem some days ago, incidentally). Just use a real syslogd (inetutils-syslogd is nice, for example, and rsyslogd and syslog-ng both have

On Wed, 2024-06-26 at 02:58 +0200, Thorsten Glaser wrote: > On Tue, 25 Jun 2024, Joseph S. Testa II wrote: > > > the way down to 6%! Additionally, I noticed that the systemd- > > journal > > You should test without that thing as well. It?s reportedly a > known bottleneck (someone on, I think, IRC said that regarding > a different problem some days ago,

On Tue, 25 Jun 2024, Joseph S. Testa II wrote: >I'm primarily interested in the performance of the default case, since >the overwhelming majority of sysadmins don't modify any options in sshd >nor syslog. If they get under attack, they?d better do. And if you?re ignoring a known bottleneck, the results will probably not be very useful? besides, not everyone is systemd-infested.

Hi, I admin a box that has Subversion users authenticate with public keys to a restricted 'svnuser' account. The comment field of all the keys describe who they belong to (it has their usernames), but unfortunately, sshd does not log this when a user successfully authenticates: Jun 21 08:18:22 localhost sshd[23636]: Accepted publickey for svnuser from x.x.x.x port 2065 ssh2 Jun

Has anyone done any initial research into how much effort it would take to port OpenSSH to Rust? If not, I might find that interesting to start. (Mind you, this would be just to get a handle on the project, not do the full porting work--unless it somehow turns out to be very easy.) - Joe -- Joseph S. Testa II Founder & Principal Security Consultant Positron Security

I've had a patch on the bugzilla for a while related to U2F with support for a few additional settings such as providing a path to a specific key to use instead of the first one found and setting if user presence is required when using the key. Is there any objection to folding those parts in if appropriate? Joseph, to offer comment on NIST P-256. There was originally quite a limited subset

Hi, Are there any open source tools to keep track of ssh sessions? For example, if a specific user is ssh logging to remote server and what commands or scripts are being run. Basically, i need to log all users sessions. Thanks in Advance and i look forward to hearing from you. Best Regards, Kaushal

On 09/13/2018 08:18 PM, Damien Miller wrote: > We have any plans to add more crypto options to OpenSSH without a strong > justification, and I don't see one for X448-SHA512 ATM. What I like about it is that it offers ~224 bit security level, whereas X25519 offers ~128 bits (according to RFC7748). Hence, pairing X448 with AES256 would provide a full chain of security in the ~224 bit

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, As of this morning, OpenSSH now has experimental U2F/FIDO support, with U2F being added as a new key type "sk-ecdsa-sha2-nistp256 at openssh.com" or "ecdsa-sk" for short (the "sk" stands for "security key"). If you're not familiar with U2F, this is an open standard for making inexpensive hardware security tokens. These are easily the cheapest way

On 09/22/2017 03:22 PM, Daniel Kahn Gillmor wrote: > On Thu 2017-09-21 18:12:44 -0400, Joseph S Testa II wrote: >> I gotta say... having a fallback mechanism here seems pretty >> strange. The entire point of the group exchange is to use a dynamic >> group and not a static one. > > fwiw, i think dynamic groups for DHE key exchange is intrinsically > problematic

Hi all, I'm interested in having X448 protocol available as an option, as it gives a larger security margin over X25519. For anyone unfamiliar, it is an Diffie-Hellman elliptic curve key exchange using Curve448 (defined in RFC7748: https://tools.ietf.org/html/rfc7748). Furthermore, it is included in the new TLS 1.3 specification (RFC8846: https://tools.ietf.org/html/rfc8446).

What I'm hearing in this thread is: "a minority of people on planet Earth have a problem with the open-source implementation of ED25519, but instead of letting that minority choose to re-implement it when/if they want to, the rest of the community needs to stall their progress in improving security." And isn't the ED25519 code is already there on their machine? So isn't

Hi all, Back in September 2018, I started a thread about implementing the X448 key exchange (see https://lists.mindrot.org/pipermail/openssh-unix-dev/2018-September/037183.html). In February 2020, RFC 8731 (formally specifying X448 in SSH) has been finalized: https://www.ietf.org/rfc/rfc8731.txt. I thought I'd start this conversation up again to see if the interest level has