sshkey批量分发,管理方案

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title: ssh 批量分发
tags: sshkey,批量,分发
grammar_cjkRuby: true

sshkey批量分发,管理方案

1. 批量发简述

linux运维工程师,每天都需要维护大量的主机,特别是互联网公司的运维工程师,需要看大量的日志,硬件状态信息,服务状态信息,有时候甚至要导入大量文件或者配置文件,这样的话,如果你还一台一台登录操的话,效率低下不用说,每天的工作往往是满满的负荷工作,而且是机械式的一台一台看。但是如果你了解熟悉ssh就不一样了,ssh可以通过主机间的互信,来免密码登录,还可以利用脚本完成一些重要的工作。比如给各个主机分发hosts文件等等。

2. ssh 连接原理

技术分享图片
ssh 建立连接方式有密码登录验证和 密钥登录验证,我们现在用的是密钥登录来让主机之间添加互信关系。其中密钥登录的原理图如上图。

  1. 客户端和服务端建立通道连接
  2. 客户端向服务端发送公钥(其中公钥和私钥都可以用ssh-keygen生成,默认生成一次就是一对,分别是公钥和私钥,私钥是保存在客户端,公钥是保存在服务端,其中生成公钥私钥可以理解为去超市买一把锁,默认都是有锁有钥匙,其中锁给服务端,钥匙自己留着,用来去服务端开锁)
  3. 客户端发送过来公钥,服务端会检查自有的known_hosts文件进行验证,如果服务端发现这次访问时第一次,它会提示客户端,让客户端敲yes后,服务端会把客户端的指纹信息写在known_hosts,然后让客户端输入服务端的密码,如果客户端输正确了,服务端会把该公钥放在自己的.ssh目录中
  4. 客户端带着私钥过来要求连接服务端
  5. 服务端用公钥质询加密发给客户端
  6. 客户端拿配套的私钥进行解密后的质询发送回服务端
  7. 验证通过,双方建立连接,客户端终于连接上了服务端

    3. scp工具解析

  8. scp命令和cp命令很像,cp是本地拷贝,scp是加密的远程拷贝,参数的区别是,-p 是保持属性,-P是端口号。
  9. scp可以把数据从一台机器推送到另一台机器,也可以从其他服务器把数据拉回本地。
  10. scp和rsync的区别是,scp不支持增量拷贝,且没有daemon模式,每一次都是全量拷贝,效率低,适合第一用,如果是增量备份还是推荐使用rsync。举例如下:
    推
    [[email protected] ~]# scp -r -p -P22  GNU-Linux-x86/  [email protected]:/tmp
    [email protected]‘s password: 
    confxml.xml                                    100% 2214     2.2KB/s   00:00    
    拉
    [[email protected] ~]# scp -p -P22 [email protected]:/tmp/rsync_fail_log.sh ~/
    [email protected]‘s password: 
    rsync_fail_log.sh                                100%    0     0.0KB/s   00:00    
    [[email protected] ~]# ls |grep rsync_fail_log.sh 
    rsync_fail_log.sh

    4. 密钥生成与分发

    密钥生成就是一对,分为公钥和私钥,公钥为锁,私钥为钥匙,所以一定要清楚,是钥匙开锁,而不是锁开钥匙。因此私钥自己留着,公钥是发给对方,然后我们可以拿着私钥去登录对方(打开对方的门)。锁的定义很形象,生成密钥可以想象中是去超市买锁,因此只要有ssh-keygen这个工具都是可以生成密钥,密钥是不限主机的,只要分清,私钥自己拿着,公钥给别人。我们一般使用dsa的密钥对,生成密钥的步骤如下:

[[email protected] .ssh]# ssh-keygen -t dsa
Generating public/private dsa key pair.
Enter file in which to save the key (/root/.ssh/id_dsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_dsa.
Your public key has been saved in /root/.ssh/id_dsa.pub.
The key fingerprint is:
b8:42:03:c2:9d:ee:bf:10:83:6c:44:a5:1f:c8:39:80 [email protected]
The key‘s randomart image is:
+--[ DSA 1024]----+
|o...             |
|E = .            |
|.O.+             |
|o.=..  .         |
| + =o . S        |
|. ..o. .         |
|   o. .          |
|    o.           |
|     o.          |
+-----------------+
[[email protected] .ssh]# ls -a
.  ..  id_dsa  id_dsa.pub
[[email protected] .ssh]# ls -l
total 8
-rw-------. 1 root root 668 May 23 01:30 id_dsa
生成密钥我们用ssh-keygen,分配公钥给对方我们使用ssh-copy-id ,
[[email protected] .ssh]# ssh-copy-id -i 192.168.50.4
/usr/bin/ssh-copy-id: ERROR: No identities found
[[email protected] .ssh]# ssh-copy-id -i id_dsa.pub 192.168.50.4 
The authenticity of host ‘192.168.50.4 (192.168.50.4)‘ can‘t be established.
RSA key fingerprint is 41:8a:f8:19:54:e2:e1:fa:eb:9e:3a:22:d2:1f:08:00.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘192.168.50.4‘ (RSA) to the list of known hosts.
[email protected]‘s password: 
Now try logging into the machine, with "ssh ‘192.168.50.4‘", and check in:

  .ssh/authorized_keys

to make sure we haven‘t added extra keys that you weren‘t expecting.

[[email protected] .ssh]# 
如果对方的ssh端口号改了,不是默认端口则我们也要改
[[email protected] .ssh]# ssh-copy-id -i id_dsa.pub "-P22 [email protected]" 
The authenticity of host ‘192.168.50.3 (192.168.50.3)‘ can‘t be established.
RSA key fingerprint is 41:8a:f8:19:54:e2:e1:fa:eb:9e:3a:22:d2:1f:08:00.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘192.168.50.3‘ (RSA) to the list of known hosts.
[email protected]‘s password: 
Now try logging into the machine, with "ssh ‘-P22 [email protected]‘", and check in:

  .ssh/authorized_keys

to make sure we haven‘t added extra keys that you weren‘t expecting

5. 文件分发实例讲解

利用ssh互信,我们可以让主机之间免密码登录,发送文件给对方,这样我们就可以通过脚本做很多事情了如下列实例:
技术分享图片
如图:存储C作为核心中的分发机,因为图中架构所有设备都处于内网内,为了提高各个主机的互访能力,因此/etc/hosts文件都对各个服务器的主机名和ip有解析。因此各个主机的hosts文件是保持一致的,现在要求以分发机的hosts文件为准,分发机C将最新的hosts文件定时分发到各主机,覆盖原来的hosts文件,这样让所有主机都可以及时更新到最新的hosts文件,这样如果hosts文件有更新的话就只要改一下分发机的hosts文件即可。分析解答如下:

  1. 我们可以通过脚本利用ssh互信免密码,将主机的hosts文件通过scp推送到各个主机,但是存在一个问题,/etc目录必须要root权限才能放进去,因此必须选择root互信才能完成需求。这样可以直接推送到/etc/下完成覆盖。

    [[email protected] .ssh]# ssh-keygen -t dsa
    Generating public/private dsa key pair.
    [[email protected] .ssh]# ls
    id_dsa  id_dsa.pub
    [[email protected] .ssh]# ssh-copy-id -i id_dsa.pub "-P22 192.168.50.2"
    The authenticity of host ‘192.168.50.2 (192.168.50.2)‘ can‘t be established.
    [[email protected] .ssh]# ssh-copy-id -i id_dsa.pub "-P22 192.168.50.3"
    The authenticity of host ‘192.168.50.3 (192.168.50.3)‘ can‘t be established.
    [[email protected] .ssh]# ssh-copy-id -i id_dsa.pub "-P22 192.168.50.4"
    The authenticity of host ‘192.168.50.4 (192.168.50.4)‘ can‘t be established
    确认是不是互信成功
    [[email protected] .ssh]# vim /service/scripts/check-ssh.sh
                                                                                              #!/usr/bin/env bash
    ##############################################################
    # File Name: /service/scripts/check-ssh.sh
    # Version: V1.0
    # Author: OuYoung
    # Blog: http://blog.51cto.com/ouyangtao
    # Created Time : 2018-05-23 12:49:19
    # Description:
    ##############################################################
    for n in 2 3 4 
    do
    echo "This is 192.168.50.$n"
    ssh [email protected]$n hostname
    done  
    [[email protected] .ssh]# sh /service/scripts/check-ssh.sh 
    This is 192.168.50.2
    mysql-B
    This is 192.168.50.3
    LAMP-A1
    This is 192.168.50.4
    backup-D
    写个简单的批发脚本,执行成功后写入crontab里,默认每30分钟执行一次分发。
    [[email protected] .ssh]# vim /service/scripts/fengfa1.sh          
    #!/usr/bin/env bash
    ##############################################################
    # File Name: /service/scripts/fengfa1.sh
    # Version: V1.0
    # Author: OuYoung
    # Blog: http://blog.51cto.com/ouyangtao
    # Created Time : 2018-05-23 13:18:25
    # Description:
    ##############################################################
    . /etc/init.d/functions
    FILE=$1
    REMOUTEDIR=$2
    if [ $# -ne 2 ]
    then
    echo "WARNINT: $0: LOCAL FILE AND REMOUTE DIR "
    exit 1;
    fi
    for n in 2 3 4
    do
    cp -r $FILE  /fengfa/  &&                        scp /fengfa/$(basename $FILE) [email protected]$n:$REMOUTEDIR >/dev/null
    if  [ $? -eq 0 ]
    then
        action "192.168.50.$n fengfa $1 is OK" true
    else
    
        action "192.168.50.$n fengfa $1 is fail" false
    fi
    done
    执行测试脚本,先在分发机上/etc/hosts文件上改动,然后执行脚本,再看每台被分发机上是否有覆盖。
    [[email protected] .ssh]# echo "# test fengfa is ok" >>/etc/hosts
    [[email protected] .ssh]# sh /service/scripts/fengfa1.sh /etc/hosts /etc
    192.168.50.2 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.3 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.4 fengfa /etc/hosts is OK                       [  OK  ]
    [[email protected] ~]# tail -1 /etc/hosts
    # test fengfa is ok
    [[email protected] .ssh]# tail -1 /etc/hosts
    # test fengfa is ok
    [[email protected] ~]# tail -1 /etc/hosts
    # test fengfa is ok
    在分发机上的cron文件写入,每三十分钟执行一次
    [[email protected] ~]# echo "*/30 * * * * sh /service/scripts/fengfa1.sh /etc/hosts /etc " >>/var/spool/cron/root
    [[email protected] ~]# crontab -l |grep "/etc/hosts"
    */30 * * * * sh /service/scripts/fengfa1.sh /etc/hosts /etc 
  2. 方法1中存在安全隐患问题,如果分发机和各个主机都是root互信的话,那么分发机就拥有所有主机的root权限,那么分发机可以随时百分百的控制各个主机,这样稍有不慎就会酿成大错,非常的不安全。我们可以在选择用普通用户做互信,先将hosts文件发送到该用户的家目录,然后给rsync添加SUID权限,然后让该用户用rsync将hosts文件在推送到本地的/etc
    [[email protected] ~]# chmod u+s /usr/bin/rsync 
    [[email protected] ~]# ls -l `which rsync`      
    -rwsr-xr-t. 1 root root 410536 Apr 30  2014 /usr/bin/rsync
    [[email protected] ~]# chmod u+s /usr/bin/rsync
    [[email protected] ~]# ls -l `which rsync`
    -rwsr-xr-x. 1 root root 410536 Apr 30  2014 /usr/bin/rsync
    [[email protected] ~]# chmod u+s /usr/bin/rsync 
    [[email protected] ~]# ls -l `which rsync`
    -rwsr-xr-x. 1 root root 410536 Apr 30  2014 /usr/bin/rsync
    我们把分发脚本稍微改一下,重新命名fengfa2.sh
    [[email protected] ~]$ vim /service/scripts/fengfa2.sh               
    #!/usr/bin/env bash
    ##############################################################
    # File Name: /service/scripts/fengfa1.sh
    # Version: V1.0
    # Author: OuYoung
    # Blog: http://blog.51cto.com/ouyangtao
    # Created Time : 2018-05-23 13:18:25
    # Description:
    ##############################################################
    . /etc/init.d/functions
    FILE=$1
    REMOUTEDIR=$2
    if [ $# -ne 2 ]
    then
    echo "WARNINT: $0: LOCAL FILE AND REMOUTE DIR "
    exit 1;
    fi
    for n in 2 3 4
    do
    cp -r $FILE  /fengfa/  &&scp /fengfa/$(basename $FILE) [email protected]$n:~/ &>/dev/null  &&ssh [email protected]$n "rsync ~/$(basename $FILE) $REMOUTEDIR" &>/dev/null                            if  [ $? -eq 0 ]
    then
        action "192.168.50.$n fengfa $1 is OK" true
    else
        action "192.168.50.$n fengfa $1 is fail" false
    fi
    done
    再次进行测试发现:
    [[email protected] ~]$ sh /service/scripts/fengfa2.sh /etc/hosts /etc
    192.168.50.2 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.3 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.4 fengfa /etc/hosts is OK                       [  OK  ]
  3. 当然方法二也不安全,把rsync的权限设置为SUID的话,那么任何用户执行rsync都可以像root执行rsync一样,那安全隐患也很大,我们继续限制让只有test用户才可以执行rsync,其他的普通用户依然不能执行rsync,这样安全性减少很多。因此我们利用sudo,在每个客户端上将rsync设置为test用户可以执行,如:
    [[email protected] ~]# chmod u-s `which rsync`
    [[email protected] ~]# echo "test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync" >>/etc/sudoers
    [[email protected] ~]# tail -1 /etc/sudoers
    test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync
    [[email protected] ~]# visudo -c
    /etc/sudoers: parsed OK
    [[email protected] ~]# chmod u-s `which rsync`
    [[email protected] ~]# echo "test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync" >>/etc/sudoers
    [[email protected] ~]# tail -1 /etc/sudoers
    test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync
    [[email protected] ~]# visudo -c
    /etc/sudoers: parsed OK
    [[email protected] ~]# chmod u-s `which rsync`
    [[email protected] ~]# echo "test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync" >>/etc/sudoers
    [[email protected] ~]# chmod u-s `which rsync`
    [[email protected] ~]# tail -1 /etc/sudoers
    test   ALL=(ALL)       NOPASSWD: /usr/bin/rsync
    [[email protected] ~]# visudo -c
    /etc/sudoers: parsed OK
    分发脚本稍微改一下,重新命名fengfa23.sh
    [[email protected] ~]$ vim /service/scripts/fengfa3.sh 
    #!/usr/bin/env bash
    ##############################################################
    # File Name: /service/scripts/fengfa1.sh
    # Version: V1.0
    # Author: OuYoung
    # Blog: http://blog.51cto.com/ouyangtao
    # Created Time : 2018-05-23 13:18:25
    # Description:
    ##############################################################
    . /etc/init.d/functions
    FILE=$1
    REMOUTEDIR=$2
    if [ $# -ne 2 ]
    then
    echo "WARNINT: $0: LOCAL FILE AND REMOUTE DIR "
    exit 1;
    fi
    for n in 2 3 4
    do
    cp -r $FILE  /fengfa/  &&scp /fengfa/$(basename $FILE) [email protected]$n:~/ &>/dev/null  &&ssh -t [email protected]$n "sudo rsync ~/$(basename $FILE) /etc/" &>/dev/null 
    if  [ $? -eq 0 ]
    then
        action "192.168.50.$n fengfa $1 is OK" true 
    else
        action "192.168.50.$n fengfa $1 is fail" false 
    fi
    done
    [[email protected] ~]$ sh /service/scripts/fengfa3.sh /etc/hosts /etc 
    192.168.50.2 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.3 fengfa /etc/hosts is OK                       [  OK  ]
    192.168.50.4 fengfa /etc/hosts is OK                       [  OK  ]

    6. 批量分发小结

    其实现在很多人批量分发都看不起sshkey,他们大都采用puppet和saltstack,诚然puppet和saltstack必然是更加专业而且更加强大,但是配置起来比起sshkey的方案难太多了,根据linux的基本原则,如果简单易用的方法可以解决需求,那请尽量选择简单易用的方案,如果不满足需求才考虑其他更优的方案,因为我们的运维法则是简单,易用,高效,毕竟ssh key才是中小企业最基本实用的批量分发,管理方案。

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