9.openssh-server
1.openssh-server
功能：讓遠程主機可以通過網絡訪問sshd服務，開始一個安全shell
2.客戶端連接方式
ssh遠程主機用戶@遠程主機ip
[root@desktop0 ~]# ssh [email protected]
The authenticity of host '172.25.0.11 (172.25.0.11)' can't be established.
ECDSA key fingerprint is eb:24:0e:07:96:26:b1:04:c2:37:0c:78:2d:bc:b0:08.
Are you sure you want to continue connecting (yes/no)? yes ##連接陌生主機時需要建立認證關係
Warning: Permanently added '172.25.0.11' (ECDSA) to the list of known hosts.
[email protected]'s password: ##遠程用戶密碼
Last login: Mon Oct 3 03:13:47 2016
[root@server0 ~]# ##登陸成功
ssh 遠程主機用戶@遠程主機ip -X ##調用遠程主機圖形工具
ssh 遠程主機用戶@遠程主機ipcommand ##直接在遠程主機運行某條命令
3.sshkey加密
1.生成公鑰私鑰
[root@server0 ~]# ssh-keygen ##生成公鑰私鑰工具
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):[enter]##加密字符保存文件（建議用默認）
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):[enter]##密鑰密碼，必須>4個字符
Enter same passphrase again:[enter]##確認密碼
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
ab:3c:73:2e:c8:0b:75:c8:39:3a:46:a2:22:34:84:81 [email protected]
The key's randomart image is:
+--[ RSA 2048]----+
|o |
|E. |
|.. |
|. . o |
|.o. * . S |
|oo.o o . |
|+ =. . . |
|o. oo.+.. |
| ..o*. |
+-----------------+
[root@server0 ~]# ls /root/.ssh/
id_rsa id_rsa.pub
id_rsa ##私鑰，就是鑰匙
id_rsa.pub ##公鑰，就是鎖
2.添加key認證方式
[root@server0 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]
ssh-copy-id ##添加key認證方式的工具
-i ##指定加密key文件
/root/.ssh/id_rsa.pub ##加密key
root ##加密用戶爲root
172.25.55.11 ##被加密主機ip
3.分發鑰匙給client主機
[root@server0 ~]# scp /root/.ssh/id_rsa [email protected]:/root/.ssh/
4.測試
[root@desktop0 ~]# ssh [email protected] ##通過id_rsa直接連接不需要輸入用戶密碼
Last login: Mon Oct 3 03:58:10 2016 from 172.25.55.11
[root@server0 ~]#
4.提升openssh的安全級別
1.openssh-server配置文件
/etc/ssh/sshd_config
78 PasswordAuthentication yes|no##是否開啓用戶密碼認證，yes爲支持no爲關閉
48 PermitRootLogin yes|no##是否允許超級用戶登陸
49 AllowUsers student westos##用戶白名單，只有在名單中出現的用戶可以使用sshd建立shell
50 DenyUsers westos##用戶黑名單
2.控制ssh客戶端訪問
vim /etc/hosts.deny
sshd:ALL ##拒絕所有人鏈接sshd服務
vim /etc/hosts.allow
sshd:172.25.55.10 ##允許10主機鏈接sshd
sshd:172.25.254.250， 172.25.254.180##允許250和180鏈接
sshd:ALL EXCEPT 172.25.55.10##只不允許10鏈接sshd
3.ssh登陸提示修改
vim /etc/motd ##顯示登陸後字符
hello zzf ##在登陸後就會顯示這個字符
