search for: weakdh

List, good afternoon, I was reading up on a TLS Diffie Hellman protocol weakness described here https://weakdh.org/sysadmin.html which is similar to the earlier FREAK attack, and can result in downgrade of cipher suites. Part of the solution workaround that the researchers describe for Dovecot here https://weakdh.org/sysadmin.html includes altering DH parameters length to 2048, and re-specifying the...

>It is not at this point emphasized anywhere, including on weakdh.org, that it is actually of high importance to regenerate your DH parameters frequently. That's not really correct. If you're using a prime of length at least 2048 bits, then the corresponding discrete-log problem is well-beyond the pre-computation ability of the NSA (or anyone else). It...

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...

Quoting Gedalya <gedalya at gedalya.net>: > On 05/26/2015 10:37 AM, Ron Leach wrote: >> https://weakdh.org/sysadmin.html >> >> includes altering DH parameters length to 2048, and re-specifying the >> allowable cipher suites - they give their suggestion. > > It looks like there is an error on this page regarding regeneration. In > current dovecots ssl_parameters_regenerate...

> 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...

On 05/27/2015 09:55 AM, Rick Romero wrote: > Quoting Gedalya <gedalya at gedalya.net>: > >> On 05/26/2015 10:37 AM, Ron Leach wrote: >>> https://weakdh.org/sysadmin.html >>> >>> includes altering DH parameters length to 2048, and re-specifying the >>> allowable cipher suites - they give their suggestion. >> >> It looks like there is an error on this page regarding regeneration. In >> current dovecots ss...

I have been reading up on TLS and Dovecot and came across this URL: https://www.weakdh.org/sysadmin.html which recommended these settings for Dovecot. I would like to know if they are correct? Some much documentation on the web is pure garbage. Dovecot These changes should be made in /etc/dovecot.conf Cipher Suites ssl_cipher_list=ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GC...

Based on the recent found weaknesses in DH key exchange, http://weakdh.org/ I increased ssl_dh_parameters_length to 2048 bits, and found waited for 5+ minutes for dovecot to come back online after a restart. Unless you got a fast machine, the initialization of DH parameters can exceed your patience. Regeneration may not be a problem (if ssl_parameters_regenerate=0 o...

...256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA > > > Why are you doing this? > I set this according to this page: https://weakdh.org/sysadmin.html It was recommended in the ArchLinux wiki page for dovecot, but it might be outdated. > >

I was reading https://weakdh.org/sysadmin.html They also have a very interesting paper as a PDF. Anyway it appears that most ssh servers, when using DHE key exchange, use the 1024-bit Oakley Group 2 and there is suspicion the NSA has done the pre-computations needed to passively decrypt any tls communication using DHE wit...

Quoting Gedalya <gedalya at gedalya.net>: > On 05/27/2015 09:55 AM, Rick Romero wrote: >> Quoting Gedalya <gedalya at gedalya.net>: >> >>> On 05/26/2015 10:37 AM, Ron Leach wrote: >>>> https://weakdh.org/sysadmin.html >>>> >>>> includes altering DH parameters length to 2048, and re-specifying the >>>> allowable cipher suites - they give their suggestion. >>> >>> It looks like there is an error on this page regarding regeneration. In >>...

On Fri 2015-05-22 00:06:29 -0400, Darren Tucker wrote: > On Thu, May 21, 2015 at 11:26 PM, Matthew Vernon <matthew at debian.org> wrote: >> >> 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? > > Would you (and any other vendors) consider generat...

On 05/26/2015 10:37 AM, Ron Leach wrote: > > https://weakdh.org/sysadmin.html > > includes altering DH parameters length to 2048, and re-specifying the > allowable cipher suites - they give their suggestion. It looks like there is an error on this page regarding regeneration. In current dovecots ssl_parameters_regenerate defaults to zero, and t...

...nd > this means regeneration is disabled. The old default was 168 hours (1 > week). > The language on http://wiki2.dovecot.org/SSL/DovecotConfiguration is > confusing and could be understood to mean that the current default is > one week. I'd read that dovecot wiki page, and the weakdh page, and - indeed - formed the impression that the defaults on our server were ok. > To enable regeneration you can manually set: > ssl_parameters_regenerate = 60 days > or: > ssl_parameters_regenerate = 1 weeks I couldn't find an entry in 10-ssl.config that covered regeneratio...

...software and a brand new > letsencrypt certificate just for email withpostfix and dovecot (that > certificate works fine with postfix). Output of dovecot --version and > dovecot -n on the new server is below. Here is my 10-ssl.conf on my CentOS box. I am using the TLS config from https://weakdh.org/sysadmin.html ------------------------------------------------------------------- ssl = yes ssl_cipher_list=ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE...

On 10 Jun 2020, at 23:18, @lbutlr <kremels at kreme.com> wrote: > IF it?s not permissions you need to provide doveconf -n output. Bloglines for any fall, panic, or error level events at a minimum. Apologies, I did not see the attachments. Will look on a real screen later.

Greetings, I have had to reinstall my email server on another Linux (centos 7.6) VPS, with a newer version of dovecot, other software and a brand new letsencrypt certificate just for email withpostfix and dovecot (that certificate works fine with postfix). Output of dovecot --version and dovecot -n on the new server is below. Now, messages ARE delivered in the right IMAP mailboxes, but when I try