Experiment Description:

In automatic deployment, other SSH machines will often operate. However, each password authentication is very annoying, especially for a long password, so SSH password free login is essential;

When there are many machines, Ansible is often used to distribute and execute SSH password free login scripts, so that each machine can be password free login.

Experimental environment:

Experimental steps:

1. Install the system and configure the network (all virtual machines need to be networked)

2. First operate the first virtual machine (ha1)

3. Write the mapping relationship between host name and IP

   1 [root@ha1 ~]# vi /etc/hosts
   2 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
   3 ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
   4 192.168.122.57    ha1
   5 192.168.122.58    ha2
   6 192.168.122.59    ha3

4. Create public key

    1 [root@ha1 ~]# ssh-keygen -t rsa 
    2 Generating public/private rsa key pair.
    3 Enter file in which to save the key (/root/.ssh/id_rsa): 
    4 /root/.ssh/id_rsa already exists.
    5 Overwrite (y/n)? y
    6 Enter passphrase (empty for no passphrase): 
    7 Enter same passphrase again: 
    8 Your identification has been saved in /root/.ssh/id_rsa.
    9 Your public key has been saved in /root/.ssh/id_rsa.pub.
   10 The key fingerprint is:
   11 40:c3:81:eb:60:49:2e:f7:fe:59:bb:ef:7d:ad:bb:06 root@ha2
   12 The key's randomart image is:
   13 +--[ RSA 2048]----+
   14 |     o+.         |
   15 |  . ....         |
   16 | o . ..          |
   17 |. * .  .         |
   18 | + +    S        |
   19 |    o       E    |
   20 |   .    .    . . |
   21 |    .  o . .  o .|
   22 |     .o o+o .o++ |
   23 +-----------------+

5. Send public key to remote machine

   1 [root@ha1 ~]# ssh-copy-id root@192.168.122.58
   2 [root@ha1 ~]# ssh-copy-id root@192.168.122.59

6. The above is the way of executing commands one by one for a single virtual machine. Write the above operations into a script (the script is at the PS at the end of this article)

7. Next, operate other virtual machines (ha2, ha3)

   1 # virtual machine ha2
   2 [root@ha2 ~]# chmod 777 build-ssh-credit.sh 
   3 [root@ha2 ~]# ./build-ssh-credit.sh 

   1 # virtual machine ha3
   2 [root@ha3 ~]# chmod 777 build-ssh-credit.sh 
   3 [root@ha3 ~]# ./build-ssh-credit.sh 

8. So far, the three virtual machines do not need to enter a password to access each other, which realizes SSH password free login

9. Complete!!!
   
   

PS: public key initialization and SSH password free login script (build SSH credit. SH), which can be directly copied for use.

#!/usr/bin/bash

# install expect，minimal No such thing rpm Package, networking or local yum source
yum install expect -y
expect << EOF
set timeout 10

# Create public key

spawn ssh-keygen -t rsa
expect {
        "*to save the key" {send "\n";exp_continue}
        "*(y/n)" {send "y\r";exp_continue}
        "Enter passphrase" {send "\n";exp_continue}
        "Enter same passphrase" {send "\n";exp_continue}
}

EOF

#  Obtain/etc/hosts In addition to documents localhost Mapping of
ip_list=`grep -v 'localhost' /etc/hosts | awk -F ' ' '{print $1,$2}'`
for ip in $ip_list
do
expect << EOF
        set timeout 2

        # Send public key
        spawn ssh-copy-id root@$ip
        expect {
                "yes/no" {send "yes\r";exp_continue}
                "password" {send "000000\r";exp_continue}
        }

        # Copy/etc/hosts File to remote machine
        spawn scp /etc/hosts $ip:/etc
        expect {
                "yes/no" {send "yes\r";exp_continue}
                "password" {send "root\r";exp_continue}
        }
EOF
done