Re: ssh_dh?
On 17 December 2018 at 07:08 Aki Tuomi < aki.tu...@open-xchange.com> wrote: On 17 December 2018 at 00:30 Daniel Miller via dovecot < dovecot@dovecot.org> wrote: Don't know if this was corrected in 2.3.4 (haven't upgraded yet but didn't see it in the notes) - but in 2.3.3 I see this in my log: imap-login: Error: Diffie-Hellman key exchange requested, but no DH parameters provided. Set ssh_dh= So...either there's an undocumented feature of SSH-over-IMAP (that's Dovecot - always on the cutting edge!) or someone had a coffee shortage during a coding session... -- Daniel It's a typo. We made non-ec DH optional in 2.3.4. This means you can remove all non-ec dh crypto algos from cipherlist. This was because ec support is pretty good and generating safe dh parameters takes a very long time, so one can simply stop supporting non-ec dh based algorithms. --- Aki Tuomi And I ment in 2.3.3. --- Aki Tuomi
Re: ssh_dh?
On 17 December 2018 at 00:30 Daniel Miller via dovecot < dovecot@dovecot.org> wrote: Don't know if this was corrected in 2.3.4 (haven't upgraded yet but didn't see it in the notes) - but in 2.3.3 I see this in my log: imap-login: Error: Diffie-Hellman key exchange requested, but no DH parameters provided. Set ssh_dh= So...either there's an undocumented feature of SSH-over-IMAP (that's Dovecot - always on the cutting edge!) or someone had a coffee shortage during a coding session... -- Daniel It's a typo. We made non-ec DH optional in 2.3.4. This means you can remove all non-ec dh crypto algos from cipherlist. This was because ec support is pretty good and generating safe dh parameters takes a very long time, so one can simply stop supporting non-ec dh based algorithms. --- Aki Tuomi
Re: ssh_dh?
Daniel, as of 2.3.x, you have to create a dh.pem parameter file unless you can convert an existing parameter file: https://wiki.archlinux.org/index.php/dovecot#Generate_DH_parame ters To generate a new DH parameters file (this will take very long): # openssl dhparam -out /etc/dovecot/dh.pem 4096 then add the file to /etc/dovecot/conf.d/10-ssl.conf ssl_dh = https://security.stackexchange.com/questions/45963/diffie-hellm an-key-exchange-in-plain-english https://security.stackexchange.com/questions/94390/whats-the-pu rpose-of-dh-parameters Yes it took a very long time, indeed five hours in my case. But now it works. I took a nap and listened to Messiah while it ground away... Enjoy... :-)
Re: ssh_dh?
Am 16.12.2018 um 23:30 schrieb Daniel Miller via dovecot: Don't know if this was corrected in 2.3.4 (haven't upgraded yet but didn't see it in the notes) - but in 2.3.3 I see this in my log: imap-login: Error: Diffie-Hellman key exchange requested, but no DH parameters provided. Set ssh_dh= So...either there's an undocumented feature of SSH-over-IMAP (that's Dovecot - always on the cutting edge!) or someone had a coffee shortage during a coding session... # doveconf -n | egrep '(2.3|_dh)' # 2.3.4 (0ecbaf23d): /etc/dovecot/dovecot.conf ssl_dh = # hidden, use -P to show it Alexander
Re: ssh_dh?
Daniel Miller via dovecot skrev den 2018-12-16 23:30: So...either there's an undocumented feature of SSH-over-IMAP (that's Dovecot - always on the cutting edge!) or someone had a coffee shortage during a coding session... its std way of drinking coffee :=) https://www.sidorenko.io/post/2014/02/secure-ssl-configuration-for-apache-postfix-dovecot/ make one for dovecot or reuse one from postfix
ssh_dh?
Don't know if this was corrected in 2.3.4 (haven't upgraded yet but didn't see it in the notes) - but in 2.3.3 I see this in my log: imap-login: Error: Diffie-Hellman key exchange requested, but no DH parameters provided. Set ssh_dh= So...either there's an undocumented feature of SSH-over-IMAP (that's Dovecot - always on the cutting edge!) or someone had a coffee shortage during a coding session... -- Daniel
