Bonjour,

la mise à jour openssh-8.8p1 désactive certains anciens protocoles utilisés par les vieux serveurs, p. ex. le portail.
Voici la parade, à ajouter dans .ssh/config:
HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa

Please note "Potentially-incompatible changes" from the release notes:
       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 [1]
       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).
       [1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
       Application to the PGP Web of Trust" Leurent, G and Peyrin, T
       (2020) https://eprint.iacr.org/2020/014.pdf

Amicalement,
Fred