Protocol major versions differ: 1 vs. 2.Â
The error above normally comes up when you try to ssh into a machine which has it’s allowed ssh protocol versions locked down to a single version, today it’s normally version 2.
In the /etc/ssh/sshd_config file there’s a “Protocol” parameter which governs the allowed protocol version. It’s normally set to “2” for better security today.
The ssh command allows you to specify a protocol version to use when establishing a connection.
To ssh using protocol version 1;
ssh -1 [ hostname]
[root@abibi ~]# ssh -1 abubu
Ro ssh using protocol version 2;
ssh -2 [ hostname]
[root@abibi ~]# ssh -2 abubu