Serveur dédié : mettre à jour OpenSSL sous Debian pour bénéficier de TLS 1.3

Cet article fait suite à un précédent tutoriel – installer la dernière version d’OpenSSL sous Debian.

Cela fait un petit moment que je voulais mettre à jour ma configuration TLS et je me suis dit que la Toussaint serait parfaite pour cela.

Aujourd’hui, le serveur passe donc à TLS 1.3, ce qui nécessite une mise à jour d’OpenSSL et la mise à jour des ciphers sous NginX.

Mise à jour d’OpenSSL

Je n’avais pas mis OpenSSL à jour depuis le dernier tuto donc il est aisé de connaitre sa version:

openssl version

Résultat :

OpenSSL v1.1.0fCode language: CSS (css)

Un autre moyen de connaître les versions disponibles dans les repos:

dpkg -l '*openssl*' | awk '/^i/{print $2}' | xargs apt-show-versions -aCode language: JavaScript (javascript)

Résultat:

openssl:amd64 1.1.0f-5 install ok installed
openssl:amd64 1.1.0f-3+deb9u2 stable debian.mirrors.ovh.net
openssl:amd64 1.1.0f-3+deb9u2 stable security.debian.org
openssl:amd64 1.1.0f-5 newer than version in archive
perl-openssl-defaults:amd64 3 install ok installed
perl-openssl-defaults:amd64 3 stable debian.mirrors.ovh.net
perl-openssl-defaults:amd64/stable 3 uptodate
python3-openssl:all 16.2.0-1 install ok installed
python3-openssl:all 16.2.0-1 stable debian.mirrors.ovh.net
python3-openssl:all/stable 16.2.0-1 uptodate

Pour obtenir la version 1.1.1 d’OpenSSL, qui est le sésame pour TLS 1.3, nous allons temporairement ajouter le repo sid, mettre à jour OpenSSL et ses dérivés puis remettre apt dans sa position stable.

On met à jour nos sources apt:

nano /etc/apt/sources.listCode language: PHP (php)

et on y ajoute sid:

deb http://ftp.debian.org/debian sid main
deb-src http://ftp.debian.org/debian sid mainCode language: JavaScript (javascript)

On met à jour apt:

apt update

Et on met à jour openssl:

apt install openssl libssl1.1Code language: CSS (css)

Résultat:

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  libc-bin libc-dev-bin libc-l10n libc6 libc6-dev libc6-i386 libnih-dbus1 libnih1 libssl-dev locales
  python-httplib2
apt-listchanges: News
---------------------

glibc (2.26-5) unstable; urgency=medium

  Starting with version 2.26-1, the glibc requires a 3.2 or later Linux
  kernel.  If you use an older kernel, please upgrade it *before*
  installing this glibc version. Failing to do so will end-up with the
  following failure:

    Preparing to unpack .../libc6_2.26-5_amd64.deb ...
    ERROR: This version of the GNU libc requires kernel version
    3.2 or later.  Please upgrade your kernel before installing
    glibc.

  The decision to not support older kernels is a GNU libc upstream
  decision.

  Note: This obviously does not apply to non-Linux kernels.

 -- Aurelien Jarno <aurel32@debian.org>  Tue, 23 Jan 2018 22:03:12 +0100

openssl (1.1.1-2) unstable; urgency=medium

  Following various security recommendations, the default minimum TLS version
  has been changed from TLSv1 to TLSv1.2. Mozilla, Microsoft, Google and Apple
  plan to do same around March 2020.

  The default security level for TLS connections has also be increased from
Suggested packages:
  glibc-doc
The following packages will be upgraded:
Setting up libc6-i386 (2.27-8) ...
Setting up python-httplib2 (0.11.3-1) ...
Processing triggers for libc-bin (2.27-8) ...
Setting up libssl1.1:amd64 (1.1.1-2) ...
locale: Cannot set LC_ALL to default locale: No such file or directory
Setting up libc-l10n (2.27-8) ...
Setting up openssl (1.1.1-2) ...
Installing new version of config file /etc/ssl/openssl.cnf ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up libc-dev-bin (2.27-8) ...
Setting up libc6-dev:amd64 (2.27-8) ...
Setting up locales (2.27-8) ...
Installing new version of config file /etc/locale.alias ...
Generating locales (this might take a while)...
  en_GB.ISO-8859-1... done
  en_GB.UTF-8... done
  en_GB.ISO-8859-15... done
Generation complete.
Setting up libnih1 (1.0.3-10+b1) ...
Setting up libnih-dbus1 (1.0.3-10+b1) ...
Setting up libssl-dev:amd64 (1.1.1-2) ...
Processing triggers for libc-bin (2.27-8) ...
Scanning processes...
Scanning candidates...
Scanning linux images...
Failed to retrieve available kernel versions.
Restarting services...
 invoke-rc.d bind9 restart
 invoke-rc.d cgmanager restart
 invoke-rc.d cgproxy restart
 invoke-rc.d fail2ban restart
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
ERROR  No section: 'Definition'
 invoke-rc.d haveged restart
 invoke-rc.d irqbalance restart
 invoke-rc.d lvm2-lvmetad restart
 invoke-rc.d lvm2-lvmpolld restart
 invoke-rc.d lwresd restart
 invoke-rc.d mdadm restart
 invoke-rc.d mdadm-waitidle restart
 invoke-rc.d minissdpd restart
 invoke-rc.d nginx restart
 invoke-rc.d opendkim restart
 invoke-rc.d opendmarc restart
 invoke-rc.d php7.2-fpm restart
 invoke-rc.d postfix restart
 invoke-rc.d redis-server restart
 invoke-rc.d rsyslog restart
 invoke-rc.d saslauthd restart
 invoke-rc.d ssh restart
Services being skipped:
 invoke-rc.d dbus restart
No containers need to be restarted.</aurel32@debian.org>Code language: PHP (php)

On teste notre nouvelle verison d’openssl:

openssl version

Résultat:

OpenSSL 1.1.1  11 Sep 2018Code language: CSS (css)

Et en un peu plus précis:

dpkg -l '*openssl*' | awk '/^i/{print $2}' | xargs apt-show-versions -aCode language: JavaScript (javascript)

Résultat:

openssl:amd64 1.1.1-2 install ok installed
openssl:amd64 1.1.0f-3+deb9u2 stable debian.mirrors.ovh.net
openssl:amd64 1.1.0f-3+deb9u2 stable security.debian.org
openssl:amd64 1.1.1-2         sid    ftp.debian.org
openssl:amd64/sid 1.1.1-2 uptodate
perl-openssl-defaults:amd64 3 install ok installed
perl-openssl-defaults:amd64 3 stable debian.mirrors.ovh.net
perl-openssl-defaults:amd64 3 sid    ftp.debian.org
perl-openssl-defaults:amd64/stable 3 uptodate
python3-openssl:all 16.2.0-1 install ok installed
python3-openssl:all 16.2.0-1 stable debian.mirrors.ovh.net
python3-openssl:all 18.0.0-1 sid    ftp.debian.org
python3-openssl:all/stable 16.2.0-1 upgradeable to 18.0.0-1

Mettre à jour les ciphers pour NginX

Il ne nous reste plus qu’à ajouter les nouveaux ciphers pour TLS 1.3 pour les services sécurisés.

Nous mettons donc la configuration des server blocks NginX à jour:

ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers "TLS13+AESGCM+AES128:EECDH+AESGCM:EECDH+CHACHA20";Code language: CSS (css)

On vérifie la configuration:

nginx -t

et on redémarre le serveur:

service nginx restart

Il ne vous reste plus qu’à vérifier votre configuration TLS sur SSL Labs.