OpenSSH RSA SHA-1 signatures

Title: OpenSSH RSA SHA-1 signatures
Author: Mike Gilbert <>
Posted: 2021-10-08
Revision: 1
News-Item-Format: 2.0
Display-If-Installed: net-misc/openssh

As of version 8.8, OpenSSH disables RSA signatures using the SHA-1
hash algorithm by default. This change affects both the client and
server components.

After upgrading to this version, you may have trouble connecting to
older SSH servers that do not support the newer RSA/SHA-256/SHA-512
signatures. Support for these signatures was added in OpenSSH 7.2.

As well, you may have trouble using older SSH clients to connect to a
server running OpenSSH 8.8 or higher. Some older clients do not
automatically utilize the newer hashes. For example, PuTTY before
version 0.75 is affected.

To resolve these problems, please upgrade your SSH client/server
whereever possible. If this is not feasible, support for the SHA-1
hashes may be re-enabled using the following config options:

HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa