Protocol major versions differ: 1 vs. 2

Protocol major versions differ: 1 vs. 2. 

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.

Old days;

#Protocol 2,1


#Protocol 2

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

  • Thanks you. it is helpful for me

  • Hariharan S

    Thank you.. Helped!

  • vamsi

    Hi Iam using fc14.

    In this Ssh version is 2 and my client ssh version is 1. So while doing scp between these iam getting errors like Protocol major versions differ: 2 vs. 1. So to use ssh 1 what changes i need to do in my server side.

    • look at the /etc/ssh/sshd_config file. Change protocol to 1

  • MohamMadi

    I know this reply is late, but this was helpful. Thanks.

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