Linux-CentOS虛擬機之間設定SSH免密登錄

1、需求：現有三臺虛擬機，設定三臺虛擬機之間互相SSH登錄時不需要密碼

如三臺虛擬機ip分別是：

192.168.1.201
192.168.1.202
192.168.1.203

2、操作步驟

• 1）首先在192.168.1.201 上執行如下命令：

ssh-keygen -t dsa

然后繼續默認輸入三次回車，如下：

• 2）分別在192.168.1.202和192.168.1.203上分別執行上述步驟1
  
  
• 3）在三臺虛擬機上分別執行如下命令：

cat /root/.ssh/id_dsa.pub

如：

• 4）在192.168.1.201上的/root/.ssh/目錄下創建authorized_keys檔案，內容為上述步驟3中查詢到的三個公鑰
  
• 5）在192.168.1.202和192.168.1.203上分別按照上述步驟4執行，即在三臺虛擬機上的/root/.ssh/目錄下創建authorized_keys檔案，然后將三臺虛擬機上的ssh產生的公鑰均放進去，即此時已經OK
• 6）驗證：

(base) [root@redrose2100 ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.201  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::ffbc:4a04:cbc5:1ad2  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::8533:7fa:153f:d6a6  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::932c:a8f0:34a8:eb30  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:83:f8:64  txqueuelen 1000  (Ethernet)
        RX packets 4941  bytes 3539336 (3.3 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2170  bytes 234901 (229.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

(base) [root@redrose2100 ~]# ssh 192.168.1.202
The authenticity of host '192.168.1.202 (192.168.1.202)' can't be established.
ECDSA key fingerprint is SHA256:GAtkLjUNBNYBgdP0BflGb20oNs7+6J3bAl/UOc4DEhw.
ECDSA key fingerprint is MD5:fd:e0:ea:11:2a:dc:80:9a:46:85:da:46:61:ab:c7:c3.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.202' (ECDSA) to the list of known hosts.
Last login: Thu Jun 10 23:37:53 2021 from 192.168.1.106
(base) [root@redrose2100 ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.202  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::ffbc:4a04:cbc5:1ad2  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::8533:7fa:153f:d6a6  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:75:8d:06  txqueuelen 1000  (Ethernet)
        RX packets 4258  bytes 3481445 (3.3 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1660  bytes 185878 (181.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

(base) [root@redrose2100 ~]# ssh 192.168.1.203
The authenticity of host '192.168.1.203 (192.168.1.203)' can't be established.
ECDSA key fingerprint is SHA256:GAtkLjUNBNYBgdP0BflGb20oNs7+6J3bAl/UOc4DEhw.
ECDSA key fingerprint is MD5:fd:e0:ea:11:2a:dc:80:9a:46:85:da:46:61:ab:c7:c3.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.203' (ECDSA) to the list of known hosts.
Last login: Thu Jun 10 23:38:00 2021 from 192.168.1.106
(base) [root@redrose2100 ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.203  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::ffbc:4a04:cbc5:1ad2  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::8533:7fa:153f:d6a6  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::932c:a8f0:34a8:eb30  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:61:96:d5  txqueuelen 1000  (Ethernet)
        RX packets 3951  bytes 3337413 (3.1 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1822  bytes 310619 (303.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

(base) [root@redrose2100 ~]# ssh 192.168.1.201
The authenticity of host '192.168.1.201 (192.168.1.201)' can't be established.
ECDSA key fingerprint is SHA256:GAtkLjUNBNYBgdP0BflGb20oNs7+6J3bAl/UOc4DEhw.
ECDSA key fingerprint is MD5:fd:e0:ea:11:2a:dc:80:9a:46:85:da:46:61:ab:c7:c3.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.201' (ECDSA) to the list of known hosts.
Last login: Thu Jun 10 23:37:40 2021 from 192.168.1.106
(base) [root@redrose2100 ~]# ifconfig ens33
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.201  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::ffbc:4a04:cbc5:1ad2  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::8533:7fa:153f:d6a6  prefixlen 64  scopeid 0x20<link>
        inet6 fe80::932c:a8f0:34a8:eb30  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:83:f8:64  txqueuelen 1000  (Ethernet)
        RX packets 5453  bytes 3597632 (3.4 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2605  bytes 283014 (276.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

(base) [root@redrose2100 ~]# exit
logout
Connection to 192.168.1.201 closed.
(base) [root@redrose2100 ~]# exit
logout
Connection to 192.168.1.203 closed.
(base) [root@redrose2100 ~]# exit
logout
Connection to 192.168.1.202 closed.
(base) [root@redrose2100 ~]#