Hello.
I have a strange warning on my /var/log/messages:
“main: sshd: ssh-rsa algorithm is disabled”
I changed my ssh keys but the warning continue to appear.
I don’t know how to stop it (I’m using ecdsa keys)
Do you have any information ?
Hey there!
This message shows up in the OpenSSH log because SHA-1 is basically nearly fully disabled. So that’s a security measure.
Could this be your answer?
https://undeadly.org/cgi?action=article;sid=20210830113413
I know that it’s disabled but the message pop like every second in my log, really annoying.
So I just want to disable it, or reduce the frequency
Nov 16 14:49:47 neurozone sshd[14783]: main: sshd: ssh-rsa algorithm is disabled
Nov 16 14:49:47 neurozone sshd[14785]: main: sshd: ssh-rsa algorithm is disabled
Nov 16 14:49:47 neurozone sshd[14787]: main: sshd: ssh-rsa algorithm is disabled
Nov 16 14:49:47 neurozone sshd[14789]: main: sshd: ssh-rsa algorithm is disabled
I can’t find the reference about how those is implemented right now, but in short it’s… as soon as SHA-1 is not available anymore (done by default on EL 9 in the crypto-policies) ssh-rsa gets disabled, but that mostly doesn’t matter nowadays
yup, but 4 messages every second is too much
I’m not aware of any config parameter to disable that 
1 Like
Hm thinking of it, could it be that shows up when the client tries to access via ssh-rsa instead of ssh-ed25519 or something else?
1 Like
I had the same question.
I currently have only one ssh connection to the server with an ecdsa key (I removed all the old keys, and recreate only one new ecdsa key)
So I doubt it
Mmmm
Found it…
My server is under attack from hackers.
they try to login on it.
1 Like
Well good that it’s secure enough so they don’t come through, good luck! 
login only by ssh key protected by password so…Yes
Need to find how to block full countries on firewalld.
Thank you for you help (I increased fail2ban mode for ssh)
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.