sshd服务篇

sshd服务

1.sshd简介

sshd = secure shell daemon
可以通过网络在主机中开启一个远程主机的shell环境的服务

服务端软件：sshd

连接方式：
ssh [email protected] ##文本模式连接全程主机
ssh -X USERNAME ##可以在连接成功后打开图形
sshd服务篇
注意：
第一次连接陌生主机是要建立认证文件，需要输入yes

远程复制：
scp FILENAME [email protected]:dir ##上传（dir为绝对路径）
scp [email protected]:dir dir ##下载（dir为绝对路径）
sshd服务篇
注意:远程复制目录时，需要加-r参数

2.sshd的key认证

[[email protected] ~]# ssh-****** ##生成**的命令
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): ##指定保存加密字符的文件（使用默认）
Created directory ‘/root/.ssh’.
Enter passphrase (empty for no passphrase): ##设定密码（空密码
Enter same passphrase again: ##确认密码
Your identification has been saved in /root/.ssh/id_rsa. ##私钥（钥匙）
Your public key has been saved in /root/.ssh/id_rsa.pub. ##公钥（锁）
The key fingerprint is:
3f:dd:83:7f:c6:51:36:c3:8b:d1:45:44:20:8d:d5:35 [email protected]
The key’s randomart image is:
+–[ RSA 2048]—-+
| .+oE*|
| … +|
| o .|
| . =o|
| S o.=|
| . . + o |
| o o o..|
| …+|
| .o |
+—————–+
sshd服务篇

2.加密服务
[[email protected] .ssh]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]
The authenticity of host ‘172.25.254.113 (172.25.254.113)’ can’t be established.
ECDSA key fingerprint is 65:4d:ac:8a:c9:58:82:b5:0c:91:c4:ef:a5:e6:f6:65.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed – if you are prompted now it is to install the new keys
[email protected]’s password:

Number of key(s) added: 1

Now try logging into the machine, with: “ssh ‘[email protected]’”
and check to make sure that only the key(s) you wanted were added.

[[email protected] .ssh]# ls
authorized_keys id_rsa id_rsa.pub known_hosts
^
此文件出现表示加密成功

3.分发**（发钥匙）
scp /root/.ssh/id_rsa [email protected]:/root/.ssh/

4.测试登陆
在客户端中（desktop）
[[email protected] ~]# ssh [email protected]
Last login: Fri Aug 10 00:52:50 2018 from foundation13.ilt.example.com
[[email protected] ~]#
连接时登陆发现不需要密码
sshd服务篇

3.sshd的安全设定

78 PasswordAuthentication yes|no ##是否允许用户通过登陆系统的密码做sshd的认证
48 PermitRootLogin yes ##是否允许root用户通过sshd服务登陆系统
Allowusers student westos ##设定用户白名单,白名单中出现的用户可以通过sshd登陆系统
Denyusers student westos ##设定用户黑名单,黑名单中出现的用户不能通过sshd登陆系统

sshd服务篇