Ca colle pas: le serveur est en OpenSSH_9.2p1 Debian-2+deb12u3.
OpenSSH 9.8p1 est dans testing, donc Debian13.
Et Debian 11 a fini en OpenSSH 8.4.
Ou alors ils ont fait une mise à jour 11->12 y a une semaine, et donc OpenSSH a 
passé la 8.8

Ceci dit, ça remarche depuis la Debian8 (OpenSSH 6.7p1-5), soit à cause de mon 
ticket au support soit à cause de mon post ici.

Merci pour le retour en tout cas

David

> Le 3 sept. 2024 à 14:25, Samuel Thibault <[email protected]> a 
> écrit :
> 
> Bonjour,
> 
> David Ponzone, le mar. 03 sept. 2024 14:13:11 +0200, a ecrit:
>> Est-ce quelqu’un a remarqué qu’une mise à jour récente d’OpenSSH sur Debian 
>> 12 (durant les 2/3 derniers mois) a littéralement torpillé les connexions 
>> depuis des vieux SSH (Debian 4, oui je sais, mais on fait pas toujours ce 
>> qu’on veut sur du legacy) et a torpillé les connexions avec auth par pubkey 
>> depuis Debian8 ?
> 
> Oui, c'est documenté dans le fichier
> /usr/share/doc/openssh-client/NEWS.Debian.gz
> 
>  OpenSSH 8.8 includes a number of changes that may affect existing
>  configurations:
> 
>   * This release disables RSA signatures using the SHA-1 hash algorithm by
>     default. This change has been made as the SHA-1 hash algorithm is
>     cryptographically broken, and it is possible to create chosen-prefix
>     hash collisions for <USD$50K.
> 
>     For most users, this change should be invisible and there is no need to
>     replace ssh-rsa keys. OpenSSH has supported RFC8332 RSA/SHA-256/512
>     signatures since release 7.2 and existing ssh-rsa keys will
>     automatically use the stronger algorithm where possible.
> 
>     Incompatibility is more likely when connecting to older SSH
>     implementations that have not been upgraded or have not closely tracked
>     improvements in the SSH protocol. For these cases, it may be necessary
>     to selectively re-enable RSA/SHA1 to allow connection and/or user
>     authentication via the HostkeyAlgorithms and PubkeyAcceptedAlgorithms
>     options. For example, the following stanza in ~/.ssh/config will enable
>     RSA/SHA1 for host and user authentication for a single destination
>     host:
> 
>         Host old-host
>             HostkeyAlgorithms +ssh-rsa
>             PubkeyAcceptedAlgorithms +ssh-rsa
> 
>     We recommend enabling RSA/SHA1 only as a stopgap measure until legacy
>     implementations can be upgraded or reconfigured with another key type
>     (such as ECDSA or Ed25519).
> 
>  OpenSSH 9.8p1 includes a number of changes that may affect existing
>  configurations:
> 
>   * DSA keys, as specified in the SSH protocol, are inherently weak: they
>     are limited to 160-bit private keys and the SHA-1 digest.  The SSH
>     implementation provided by the openssh-client and openssh-server
>     packages has disabled support for DSA keys by default since OpenSSH
>     7.0p1 in 2015, released with Debian 9 ("stretch"), although it could
>     still be enabled using the HostKeyAlgorithms and
>     PubkeyAcceptedAlgorithms configuration options for host and user keys
>     respectively.
> 
>     The only remaining uses of DSA at this point should be connecting to
>     some very old devices.  For all other purposes, the other key types
>     supported by OpenSSH (RSA, ECDSA, and Ed25519) are superior.
> 
>     As of OpenSSH 9.8p1, DSA keys are no longer supported even with the
>     above configuration options.  If you have a device that you can only
>     connect to using DSA, then you can use the ssh1 command provided by the
>     openssh-client-ssh1 package to do so.
> 
> Samuel

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