SSH no hostkey alg

When connecting to an Ubuntu 24.04 server from CentOS 6 server, i got error “no hostkey alg”

root@server12:~# ssh [email protected]
no hostkey alg
root@server12:~#

To fix this error, edit /etc/ssh/sshd_config on Ubuntu server and add followng to end of the file

HostKeyAlgorithms +ssh-rsa,ssh-dss
PubkeyAcceptedKeyTypes +ssh-rsa,ssh-dss

Restart ssh service on Ubuntu

systemctl restart ssh

Now you should be able to connect to Ubuntu server from CentOS 6 using SSH. If you are using ssh key auth, use RSA key, newer keys like ed25519 won’t work and result in following error message

root@server12:~# ssh [email protected]
key_from_blob: remaining bytes in key blob 36
key_to_blob: unsupported key type 11
Permission denied (publickey).
root@server12:~# 

Once the ile transfer is done, edit /etc/ssh/sshd_config on ubuntu server and remove the older (less secure) algorithms.

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