You will get the error: Unknown cipher type when trying to exchange keys with some Rocky Linux 8.6
Unknown cipher type 'aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc'
The reason is that (c)XSIBackup tries to use some fixed set of ciphers when probing the remote end for the type of system.
Now the thing is that for some reason OpenSSL fails to negotiate a cipher if only one of the ciphers presented in the list is not present. This is some ackward behaviour in our humble opinión, still that's what it is.
We will fix this by using a widely available cipher such as aes128-ctr or similar for the remote system probe or just allow it to work in automatic mode.