SSH Password-free login

SSH Password-free login


SSH login with no password to use the public and private keys. Linux can be used to generate a public/private key pair with Ssh-keygen, below I take CentOS as an example.

There is machine A (192.168.1.155), B (192.168.1.181). Now want to a through SSH password-free login to B.

1. Generate a public/private key pair under the a machine.
[[email protected] ~]$ ssh-keygen-t rsa-p '


-P for the password,-p ' means the empty password, you can not use the-p parameter, so that three cars to enter, with-P on a return.

It generates the. SSH directory under/HOME/CHENLB, with Id_rsa and id_rsa.pub under SSH.
The following command produces different types of keys
Ssh-keygen-t DSA
SSH-KEYGEN-T RSA
Ssh-keygen-t RSA1



2. Copy the id_rsa.pub under the A machine to the B machine, in the. ssh/authorized_keys file of the B machine, this is not a folder and is copied with SCP.
[Email protected] ~]$ SCP. Ssh/id_rsa.pub 192.168.1.181:/home/
[email protected] ' s password:
Id_rsa.pub 100% 223 0.2kb/s 00:00


Since there is no password-free login, enter the password.

The 3.B Machine writes the id_rsa.pub copied from a machine into the. ssh/authorzied_keys file.
[email protected] ~]$ cat id_rsa.pub >>. Ssh/authorized_keys
[Email protected] ~]$ chmod Ssh/authorized_keys


Authorized_keys's permission if 600.

4.A Machine login B machine.
[[email protected] ~]$ ssh 192.168.1.181
The authenticity of host ' 192.168.1.181 (192.168.1.181) ' can ' t be established.
RSA key fingerprint is 00:a6:a8:87:eb:c7:40:10:39:cc:a0:eb:50:d9:6a:5b.
Is you sure want to continue connecting (yes/no)? Yes
warning:permanently added ' 192.168.1.181 ' (RSA) to the list of known hosts.
Last Login:thu Jul 3 09:53:18 from CHENLB
[Email protected] ~]$


The first time you log in is when you want to enter Yes.

Now a machine can be no password login B machine.

Summary: Log on the machine can have a private key, the machine to be logged on to have the public key of the machine. This public/private key pair is typically generated on the private key host. Above is the RSA algorithm's public/private key pair, of course, you can also use DSA (the corresponding file is id_dsa,id_dsa.pub)

Want to let A, B machine without password mutual login, that machine is configured in the same manner as above.

SSH Password-free login