Linux_入门 远程连接访问主机
1.openssh-server
功能：让远程主机可以通过网络访问sshd服务，开始一个安全shell
2.客户端连接方式
ssh 远程主机用户@远程主机ip
[[email protected] ~]# 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 ##连接陌生主机时需要建立认证关系
Warning: Permanently added '172.25.0.11' (ECDSA) to the list of known hosts.
[email protected]'s password: ##远程用户密码
Last login: Mon Oct 3 03:13:47 2016
[[email protected] ~]# ##登陆成功
ssh 远程主机用户@远程主机ip -X ##调用远程主机图形工具
ssh 远程主机用户@远程主机ip command ##直接在远程主机运行某条命令
3.sshkey加密
1.生成公钥私钥
[[email protected] ~]# ssh-****** ####生成公钥私钥工具
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): ######加密字符保存文件（建议用默认）
Enter passphrase (empty for no passphrase): ##**密码，必须>4个字符
Enter same passphrase again: ##确认密码
Passphrases do not match. Try again. ###两次输入不匹配
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
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:
43:c5:1b:27:79:64:31:8b:4e:08:c1:19:fe:c3:0b:58 [email protected]
The key's randomart image is:
+--[ RSA 2048]----+
| .++ ..o=. |
| .o. o=ooo |
| E o o*. |
| o + o. |
| . . S . |
| . + |
| . |
| |
| |
+-----------------+
id_rsa ##私钥，就是钥匙
id_rsa.pub ##公钥，就是锁
2.添加key认证方式
3.分发钥匙给client主机
4.测试
4.提升openssh的安全级别
1.openssh-server配置文件
/etc/ssh/sshd_config
78 PasswordAuthentication yes|no ##是否开启用户密码认证，yes为支持no为关闭
48 PermitRootLogin yes|no ##是否允许超级用户登陆
49 AllowUsers student westos ##用户白名单，只有在名单中出现的用户可以使用sshd建立shell
50 DenyUsers westos ##用户黑名单
2.控制ssh客户端访问
vim /etc/hosts.deny
sshd:ALL ##拒绝所有人链接sshd服务
vim /etc/hosts.allow
sshd:172.25.254.250 ##允许250主机链接sshd
sshd:172.25.254.250， 172.25.254.180 ##允许250和180链接
sshd:ALL EXCEPT 172.25.254.200 ##只不允许200链接sshd
3.ssh登陆提示修改该
vim /etc/motd ##显示登陆后字符
hello world ##在登陆后就会显示这个字符