sshd远程连接服务

####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####

为了便于区分设置不同的shell颜色，白底黑字为客户端，黑底白字为服务端。

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

sshd远程连接服务

####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):[enter]    ##加密字符保存文件（建议用默认）
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):        [enter]       ##**密码，必须>4个字符
Enter same passphrase again:                [enter]       ##确认密码
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*.         |
+-----------------------+
[[email protected] ~]# ls /root/.ssh/
id_rsa id_rsa.pub
id_rsa       ##私钥，就是钥匙

id_rsa.pub ##公钥，就是锁

sshd远程连接服务

2.添加key认证方式
[[email protected] ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]
ssh-copy-id       ##添加key认证方式的工具
-i           ##指定加密key文件
/root/.ssh/id_rsa.pub   ##加密key
root           ##加密用户为root

172.25.0.11 ##被加密主机ip

3.分发钥匙给client主机
[[email protected] ~]# scp /root/.ssh/id_rsa [email protected]:/root/.ssh/

sshd远程连接服务

4.测试

[[email protected] ~]# ssh [email protected] ##通过id_rsa直接连接不需要输入用户密码
Last login: Mon Oct 3 03:58:10 2016 from 172.25.0.250

[[email protected] ~]#

sshd远程连接服务

####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

白名单默认为已写入黑名单的用户可以被连接，其余用户不可以被连接。

sshd远程连接服务