Ssh password-free login

Ssh password-less login uses public and private keys. Under linux, you can use ssh-keygen to generate public / private key pairs. Let me take redhat 5 as an example.

There are machines A (192.168.122.223) and B (192.168.122.222). Now I want A to log in to B through ssh password-free.

1. Generate a public key / private key pair under machine A.

Add the-P parameter item to indicate the password, and-P''means the empty password, or you don't need the-P parameter, so you have to enter three cars and enter once with-P.

It generates a .ssh directory under / root, with id_rsa and id_rsa.pub under .ssh.

two。 Copy the id_rsa.pub under A machine to B machine, and in the .ssh/authorized_keys file of B machine, I copy it with scp.

Since there is no password-free login, you need to enter a password.

3.B machine adds the id_rsa.pub copied from machine A to the .ssh / authorized_keys file.

The permission of authorized_keys is 600.

4. Machine A logs in to machine B.

Now machine A can log in to machine B without a password.

Summary: the login machine can have a private key, and the logged-in machine must have the public key of the login machine. This public / private key pair is usually generated on the private key host. The above is the public / private key pair using the rsa algorithm, of course, you can also use dsa (the corresponding file is id_dsa,id_dsa.pub)

If you want An and B machines to log in to each other without a password, then B machines can be configured in the same way as above.