6. SSH远程管理服务实战

1. SSH基本概念?

ssh是一个应用层安全协议

2.SSH主要的功能是?

实现远程登录, 数据传输过程中进行加密. 钉钉(澡堂模式)
远程登录:
ssh
telnet

3.SSH与Telnet之间有什么区别?

4.抓包分析SSH与Telnet的区别?

    所需工具：Wireshark
    [[email protected] ~]# yum install telnet-server -y
    [[email protected] ~]# systemctl start telnet.socket

    [[email protected] ~]$ echo oollddbbooyy  |sed -r 's#(.)(.)#\1#g'
    oldboy

    PS:
        服务器都是使用的SSH协议实现的远程登录
        对于路由器  交换机  全是走的telnet协议  (  Web界面调试  )
    

5.SSH相关客户端指令ssh、scp、sftp?

    1.ssh   ( Windows系统:①Xshell ②Crt )   ( Mac系统: ①ssh命令  ②Crt )
    [[email protected] ~]# ssh [email protected]
    [email protected]'s password: 

    2.scp:   rsync增量    scp 全量(每次都是覆盖)  ssh协议
    拷贝目录 需要  -r参数
    推送
    [[email protected] ~]# scp ./web-file [email protected]:/tmp

    获取
    [[email protected] ~]# scp  [email protected]:/tmp/web-file  ./test

    限速 ( kb  1024 * 8 = 实际的传输速率 )
    [[email protected] ~]# scp -l 8192 ./1.txt 172.16.1.41:/tmp
    [email protected]'s password:
    1.txt                           14%   74MB   1.0MB/s   07:09 

    3.sftp 文件传输协议?
        为什么不适用命名的方式?  为什么使用xftp?
            1.简单,带图形,支持断点续传,支持暂停

6.SSH远程登录方式、用户密码、秘钥方式?

1.基于用户和密码的方式
    1.密码太复杂容易忘  工具：lastpass（适用于多终端）
    2.密码太简单不安全

2.基于密钥的方式实现     (指纹)
    1.降低密码泄露风险
    2.提升用户的便捷性

3.实现免密码登录方式
     3.1创建一对密钥   公钥+私钥 ==配套
    [[email protected] ~]# ssh-keygen -C [email protected]   //一路回车即可
    Generating public/private rsa key pair.
    Enter file in which to save the key (/root/.ssh/id_rsa):
    Created directory '/root/.ssh'.
    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:
    SHA256:gk2zFs5LuoV4Jf381EaFnaHvRZu36qLqIcYUma17SeU [email protected]
    The key's randomart image is:
+---[RSA 2048]----+
|              .  |
|      +      + o |
|     ++. .  o + .|
|     Bo+o    o .o|
|    [email protected]  . .oo|
|   .oBo=.  o . .o|
|  . +=o+o . o .. |
|   ..oo .o o  .  |
|    . .o..o oo   |
+----[SHA256]-----+

    3.2 将管理机的公钥推送至web服务器上   ( 需要输入对端服务器的密码  )
    [[email protected] ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '172.16.1.7 (172.16.1.7)' can't be established.
ECDSA key fingerprint is SHA256:INgxiiDMWAw79GeJRGUjsLmXJmXbHDXyAJqV8wFxhpI.
ECDSA key fingerprint is MD5:78:6a:d4:ad:13:4a:c9:17:cb:3a:4d:cf:2f:c8:2c:08.
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.

    3.3 使用 ssh 命令 连接 对应的服务器   ( 检查是否免密码  )
    [[email protected] ~]# ssh '[email protected]'

    3.4有问题查看日志信息
    tail -f /var/log/secure

ssh无密码登录失败分析

7.SSH场景实践，借助SSH免秘实现跳板机功能?

8.SSH远程连接功能安全优化? fail2ban又是啥?(研究)

    1.更改远程连接登陆的端口       port 6666
    2.禁止ROOT管理员直接登录     PermitRootLogin no
        直接  xshell  -->root   --> server   (禁止用户名密码  禁止密钥)
        间接  xshell  -->oldxu  --> server  ---> su - root
    3.密码认证方式改为密钥认证      PasswordAuthentication no
    4.重要服务不使用公网IP地址     !!!!!!!!!!!!!!!!!
    5.使用防火墙限制来源IP地址     软件防火墙  |  硬件防火墙

        10.0.0.1(其他人)    --->  10.0.0.61        异常
        10.0.0.100(公司)    --->  10.0.0.61       正常

    6.修改后的配置  [测试完后记得还原]
    [[email protected] ~]# vim /etc/ssh/sshd_config
    Port 6666                       # 变更SSH服务远程连接端口
    PermitRootLogin         no      # 禁止root用户直接远程登录
    PasswordAuthentication  no      # 禁止使用密码直接远程登录
    UseDNS                  no      # 禁止ssh进行dns反向解析，影响ssh连接效率参数
    GSSAPIAuthentication    no      # 禁止GSS认证，减少连接时产生的延迟

    域名解析IP
    IP解析域名

    

9.fail2ban(研究)

ail2ban可以监控系统日志，并且根据一定规则匹配异常IP后使用Firewalld将其屏蔽，尤其是针对一些爆破/扫描等非常有效。

1.开启Firewalld防火墙
[[email protected] ~]# systemctl start firewalld
[[email protected] ~]# systemctl enable firewalld
[[email protected] ~]# firewall-cmd --state
running

2.修改firewalld规则，启用Firewalld后会禁止一些服务的传输，但默认会放行常用的22端口, 如果想添加更多，以下是放行SSH端口（22）示例，供参考：

#放行SSHD服务端口
[[email protected] ~]# firewall-cmd --permanent --add-service=ssh --add-service=http
#重载配置
[[email protected] ~]# firewall-cmd --reload
#查看已放行端口
[[email protected] ~]# firewall-cmd  --list-service
3.安装fail2ban,需要有epel

[[email protected] ~]# yum install fail2ban fail2ban-firewalld mailx -y
4.配置fail2ban规则.local会覆盖.conf文件

[[email protected] fail2ban]# cat /etc/fail2ban/jail.local
[DEFAULT]
ignoreip = 127.0.0.1/8
bantime  = 86400
findtime = 600
maxretry = 5
banaction = firewallcmd-ipset
action = %(action_mwl)s

[sshd]
enabled = true
filter  = sshd
port    = 22
action = %(action_mwl)s
logpath = /var/log/secure
5.启动服务，并检查状态

[[email protected] ~]# systemctl start fail2ban.service
[[email protected] ~]# fail2ban-client status sshd

6.清除被封掉的IP地址
[[email protected] ~]# fail2ban-client set sshd unbanip 10.0.0.1

10.SSH如何结合Google Authenticator 实现双向验证? (适合个人使用)

    基于密码 + 动态口令     支持
    基于密钥 + 动态口令     不支持
    https://www.xuliangwei.com/bgx/1345.html

原文地址：https://www.cnblogs.com/yinwu/p/11509289.html