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–>
第五章 SSH远程管理服务实战
第五章 SSH远程管理服务实战1. SSH基本概述2. SSH相关命令3. SSH验证方式4. SSH场景实践5. SSH安全优化
1. SSH基本概述
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SSH是一个安全协议，在进行数据传输时，会对数据包进行加密处理，加密后在进行数据传输。确保了数据传输安全。那SSH服务主要功能有哪些呢？
1. 提供远程连接服务器的服务
2. 对传输的数据进行加密
那么除了SSH协议能提供远程连接服务，Telnet也能提供远程连接服务, 那么分别的区别是什么呢?
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SSH服务会对传输数据进行加密, 监听在本地22/tcp端口, ssh服务默认支持root用户登录
Telnet服务不对数据进行加密, 监听在本地23/tcp端口, Telnet默认不支持root用户登录
| 服务连接方式 | 服务数据传输 | 服务监听端口 | 服务登陆用户 |
|---|---|---|---|
| SSH | 加密 | 22/tcp | 默认支持root用户登陆 |
| Telnet | 明文 | 23/tcp | 不支持root用户登陆 |
案例: 使用wireshark验证telnet明文传输与ssh加密传输
1.安装 Telnet服务并运行
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[root@m01 ~]# yum install telnet-server -y
[root@m01 ~]# systemctl start telnet.socket
2.使用wireshark检测vmnet8网卡上telnet的流量
3. telnet是无法使用root用户登录Linux系统，需要创建普通用户
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[root@m01 ~]# useradd qls
[root@m01 ~]# echo "1"| passwd --stdin qls
4. 使用普通用户进行telnet登录
5. 搜索wireshark包含telnet相关的流量
6. 使用wireshark分析ssh流量
2. SSH相关命令
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SSH有客户端与服务端，我们将这种模式称为C/S架构，ssh客户端支持Windows、Linux、Mac等平台。
在ssh客户端中包含 ssh|slogin远程登陆、scp远程拷贝、sftp文件传输、ssh-copy-id秘钥分发等应用程序。
1. ssh远程登录服务器命令示例
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ssh -p22 root@10.0.0.61
# -p指定连接远程主机端口，默认22端口可省略
# root@remotehost
# "@"前面为用户名，如果用当前用户连接，可以不指定用户
# "@"后面为要连接的服务器的IP
2. scp复制数据至远程主机命令(全量复制)
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# -P 指定端口，默认22端口可不写
# -r 表示递归拷贝目录
# -p 表示在拷贝文件前后保持文件或目录属性不变
# -l 限制传输使用带宽(默认kb)
#推：将本地/tmp/qls推送至远端服务器10.0.0.61的/tmp目录，使用对端的root用户
[root@m01 ~]# scp -P22 -rp /tmp/qls root@10.0.0.61:/tmp
#拉：将远程10.0.0.61服务器/tmp/oldboy文件拉取到本地/opt/目录下
[root@m01 ~]# scp -P22 -rp root@10.0.0.61:/tmp/qls /opt/
#限速
[root@m01 ~]# scp /opt/1.txt root@172.16.1.31:/tmp
root@172.16.1.31 password:
test 100% 656MB '83.9MB/s' 00:07
#限速为8096kb，换算为MB，要除以 8096/8=1024KB=1MB
[root@m01 ~]# scp -rp -l 8096 /opt/1.txt root@172.16.1.31:/tmp
root@172.16.1.31s password:
test 7% 48MB '1.0MB/s' 09:45
#结论：
1.scp通过ssh协议加密方式进行文件或目录拷贝。
2.scp连接时的用户作为为拷贝文件或目录的权限。
3.scp支持数据推送和拉取，每次都是全量拷贝，效率较低。
3. Sftp远程数据传输命令
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# sftp> --- 进入到ftp文件传输模式（ftp相关命令）
# bye --- 离开ftp模式
# cd path --- 切换远程主机的目录
# get --- 从远程服务器上将数据下载到本地
# lcd /tmp --- 进行本地切换目录信息
# lpwd --- 查看本地所在路径信息
# put --- 进行数据上传操作
#默认可以通过sftp命令连接sftp服务
sftp root@10.0.0.61
sftp -oPort=52113 root@10.0.0.61 #sftp的特殊端口连接
# sftp使用get下载文件至于本地服务器
sftp> get conf.txt /tmp/
# sftp使用put上传本地服务器文件至远程服务器
sftp> put /root/t1.txt /root/
3. SSH验证方式
1. 基于账户密码远程登录
知道服务器的IP端口，账号密码，即可通过ssh客户端命令登陆远程主机。
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[C:\~]$ ssh -p22 root@10.0.0.61
root@10.0.0.61 password:
[root@m01 ~]#
2. 基于秘钥远程登录
默认情况下，通过ssh客户端命令登陆远程服务器，需要提供远程系统上的帐号与密码，但为了降低密码泄露的机率和提高登陆的方便性，建议使用密钥验证方式。
01. 在服务器上生成非对称密钥，使用-t指定密钥类型,使用-C指定用户邮箱
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[root@m01 ~]# ssh-keygen -t rsa -C 1176494252@qq.com
...
#默认一路回车即可
...
02. 将A服务器上的公钥推送至B服务器
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#命令示例: ssh-copy-id [-i [identity_file]] [user@]machine
ssh-copy-id #命令
-i #指定下发公钥的路径
[user@] #以什么用户身份进行公钥分发（root）,如果不输入，表示以当前系统用户身份分发公钥
machine #下发公钥至那台服务器, 填写远程主机IP地址
#分发秘钥，[将A服务器的公钥写入B服务器~/.ssh/authorized_keys文件中]
[root@m01 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@172.16.1.41
03. A服务器连接B服务器是无需密码的，如果能直接连接无需密码则表示秘钥已配置成功
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#远程登录对端主机方式
[root@m01 ~]# ssh root@172.16.1.41
[root@nfs ~]#
#不登陆远程主机bash，但可在对端主机执行命令
[root@m01 ~]# ssh root@172.16.1.41 "hostname -i"
172.16.1.41
4. SSH场景实践
实践场景，用户通过Windows/MAC/Linux客户端连接跳板机免密码登录，跳板机连接后端无外网的Linux主机实现免密登录，架构图如下。
实践多用户登陆一台服务器无密码
实践单用户登陆多台服务器免密码
1. Windows客户端使用Xshell生成秘钥对，并下发公钥至跳板机
1) Xshell–>选择工具->新建密钥生成工具
2) 生成公钥对，选择下一步
3) 填写秘钥名称。秘钥增加密码则不建议配置
4) Windows会提示密码，继续即可
5) 生成秘钥后，点击Xshell->工具->用户秘钥管理者->选择对应秘钥的属性
6) 选择对应秘钥的公钥，将其复制
7) 将从Windows下复制好的公钥粘贴至跳板机~/.ssh/authorized_keys中，然后测试
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[root@m01 ~]# cd ; umask 077; mkdir -p .ssh ;cd .ssh
[root@m01 .ssh]# vim authorized_keys #添加windows公钥
2. 跳板机下发公钥至后端主机
1) 在跳板机上生成秘钥对
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[root@m01 ~]# ssh-keygen -t rsa -C 1176494252@qq.com
2) 拷贝跳板机上的密钥至后端主机，如果SSH不是使用默认22端口,使用-p指定对应端口
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[root@m01 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub "-p22 root@172.16.1.31"
[root@m01 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub "-p22 root@172.16.1.41"
3) 在m01管理机上测试是否成功登陆两台服务器
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[root@m01 ~]# ssh root@172.16.1.41
[root@nfs01 ~]# exit
[root@m01 ~]# ssh root@1172.16.1.31
[root@backup ~]# exit
3. 通过跳板机能实现scp拷贝文件免密码
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[root@manager ~]# scp /etc/hosts root@172.16.1.31:/tmp
/etc/hosts 100% 0 0.0KB/s 00:00
[root@manager ~]# scp /etc/hosts root@172.16.1.41:/tmp
/etc/hosts 100% 0 0.0KB/s 00:00
请思考以下几个问题？
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#问题一：
执行：ssh qls@10.0.0.51 能不能连接？
说明：基于密钥连接，会识别用户身份信息
#问题二：
密钥分发的实际过程：执行ssh-copy-id命令都干了什么？
01) 将公钥文件传输到被管理服务器相应用户的家目录中
[root@m01 ~]# scp -rp ~/.ssh/id_dsa.pub root@10.0.0.51:~
输入密码
02) 被管理服务在家目录下面创建一个.ssh目录
[root@m01 ~]# mkdir ~/.ssh/
03) 将公钥文件移动到.ssh目录中，并进行修改名称和授权
[root@m01 ~]# mv ~/id_dsa.pub ~/.ssh/authorized_keys
[root@m01 ~]# chmod 600 ~/.ssh/authorized_keys
04) 为什么要进行重命名?
[root@m01 ~]# cat /etc/ssh/sshd_config
47 AuthorizedKeysFile .ssh/authorized_keys
#问题三：
如何实现自动批量分发公钥？
#!/bin/bash
# 删除旧的密钥对
rm -f ~/.ssh/id_rsa*
# 创建密钥对
ssh-keygen -t rsa -f ~/.ssh/id_rsa -N "" &>/dev/null
# 批量分发公钥的操作
for ip in 5 6 7 8 9 31 41 51 61 71
do
sshpass -p1 ssh-copy-id -i ~/.ssh/id_rsa.pub "-o StrictHostKeyChecking=no" 172.16.1.$ip &>/dev/null
if [ $? -eq 0 ];then
echo -e "\033[32mhost 172.16.1.$ip Distribution of the secret key Success!!! \033[0m"
echo
else
echo -e "\033[31mhost 172.16.1.$ip Distribution of the secret key Failed !!! \033[0m"
echo
fi
done
5. SSH安全优化
SSH作为远程连接服务，通常我们需要考虑到该服务的安全，所以需要对该服务进行安全方面的配置。
1.更改远程连接登陆的端口
2.禁止ROOT管理员直接登录
3.密码认证方式改为密钥认证
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
SSH服务登录防护需进行如下配置调整，先对如下参数进行了解
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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
将如下具体配置添加至/etc/ssh/sshd_config文件中，参数需根据实际情况进行调整
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###SSH###
#Port 6666
#PasswordAuthentication no
#PermitRootLogin no
GSSAPIAuthentication no
UseDNS no
###END###
#注意：修改完配置文件一定要重启生效。
