Centos7如何升级openSSH

软件实施干货分享 2020-04-24

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因为服务器被扫描出来openssh漏洞，客户要求必须尽快修复，所以研究了一下漏洞报告，发现通过把openssh升级至最新版本可以有效规避漏洞。

升级之前我们首先要了解到，万一我们升级openssh失败的话，会造成什么后果，后果就是无法远程登陆服务器！

为了避免SSH升级失败造成远程登录失败的情况发生，首先要开启linux服务器的telnet服务，万一SSH登录失败，可以telnet登录服务器进行一些挽救操作。但是切记升级完成确认无问题之后，最好关闭telnet服务，因为telnet服务并不安全。

话不多说，开始进入正题

一、centos7 telnet服务的安装和启动

①在安装Telnet前先检查系统是否安装了telnet-server和xinetd

rpm -qa | grep telnet
rpm -qa | grep xinetd

如果没有安装，则开始安装，安装之前先查找Telnet的安装包

yum list | grep telnet
yum list | grep xinetd

②开始安装，客户端和服务端

yum -y install telnet-server.x86_64
yum -y install telnet.x86_64
yum -y install xinetd.x86_64

注：telnet-server服务启动依赖xinetd服务。

xinetd：eXtended InterNET services daemon，超级Internet服务器，用来管理多种轻量级Internet服务。

查看是否安装xinetd (若安装则不安装)：

[root@localhost ~]# rpm -qa | grep xinetd

如果未安装，则安装

[root@localhost init.d]# yum -y install xinetd

③telnet服务默认是不开启的，修改文件/etc/xinetd.d/telnet来开启服务

备注：telnet文件如有则修改，若不存在，可自己vi创建修改：修改 disable = yes 为 disable = no

# default: yes
# description: The telnet server servestelnet sessions; it uses \
# unencrypted username/password pairs for authentication.
service telnet
{  
  flags           = REUSE  
  socket_type     = stream  
  wait            = no  
  user            = root  
  server          =/usr/sbin/in.telnetd  
  log_on_failure  += USERID  
  disable         = no

④安装后检查

[root@192 ~]# rpm -qa | grep telnet
telnet-0.17-64.el7.x86_64
telnet-server-0.17-64.el7.x86_64
[root@192 ~]# rpm -qa | grep xinetd
xinetd-2.3.15-13.el7.x86_64
[root@192 ~]#

⑤启动telnet和依赖的xinetd服务

在centos7之前：

$ service  xinetd restart

或

$ /etc/rc.d/init.d/xinetd  restart

在centos7中(无xinetd的service启动项)：

[root@CentOS-Slave1 xinetd.d]# service xinetd restart  
Redirecting to /bin/systemctl restart  xinetd.service

或

[root@CentOS-Slave1 xinetd.d]# systemctl restart  xinetd.service 
# /bin/systemctl restart  xinetd.service

查看启动情况：

[root@CentOS-Slave1 xinetd.d]# ps -ef | grep xinetd  
root      6641     1  0 23:22 ?        00:00:00 /usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid  
root      6644  5817  0 23:24 pts/3    00:00:00 grep --color=auto xinetd

⑥测试telent，输入ip+用户名+密码登陆

[root@CentOS-Slave1 pam.d]# telnet 192.168.10.56

⑦设置服务开机启动：

[root@CentOS-Slave1 rc3.d]# chkconfig --level 35 xinetd on  
Note: Forwarding request to 'systemctl enable xinetd.service'.  
[root@CentOS-Slave1 rc3.d]# systemctl enable xinetd.service

⑧查看

[root@CentOS-Slave1 rc3.d]# chkconfig --list

⑨问题备注（可能出现的）

telnet下root登录,密码正确,总提示：Login incorrect
解决1：注释/etc/pam.d/remote的第一行,
即:auth required pam_securetty.so

二、SSH升级(严格按照文档，保准没问题)

如果ssh版本过低，最好先yum update openssh升级下到目前yum仓库默认的openssh7.4p1版本

默认centos7.3的ssh是如下版本

[root@linux-node3 ~]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)
[root@linux-node3 ~]# ssh -V
OpenSSH_6.6.1p1, OpenSSL 1.0.1e-fips 11 Feb 2013
[root@linux-node3 ~]#

执行yum update openssh先升级下（反正官方提供的这种升级是没问题的。如果之前手动编译操作过openssh的升级，变更了默认配置文件路径什么的请自行测试。）

（这里准备统一openssh版本为7.4p1之后再统一编译安装升级到openssh8.xp1）

[root@linux-node3 ~]# yum update openssh -y
 
[root@linux-node3 ~]# ssh -V
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017
[root@linux-node3 ~]#

安装依赖包

升级需要几个组件，有些是和编译相关的等

[root@linux-node3 ~]# yum install  -y gcc gcc-c++ glibc make autoconf openssl openssl-devel pcre-devel  pam-devel
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.163.com
 * epel: mirrors.aliyun.com
 * extras: mirrors.cn99.com
 * updates: mirrors.cn99.com
Package gcc-4.8.5-36.el7_6.1.x86_64 already installed and latest version
Package gcc-c++-4.8.5-36.el7_6.1.x86_64 already installed and latest version
Package glibc-2.17-260.el7_6.4.x86_64 already installed and latest version
Package 1:make-3.82-23.el7.x86_64 already installed and latest version
Package autoconf-2.69-11.el7.noarch already installed and latest version
Package 1:openssl-1.0.2k-16.el7_6.1.x86_64 already installed and latest version
Package 1:openssl-devel-1.0.2k-16.el7_6.1.x86_64 already installed and latest version
Package pcre-devel-8.32-17.el7.x86_64 already installed and latest version
Package pam-devel-1.1.8-22.el7.x86_64 already installed and latest version
Nothing to do
[root@linux-node3 ~]#

安装pam和zlib等（后面的升级操作可能没用到pam，安装上也没啥影响，如果不想安装pam请自行测试）

[root@linux-node3 ~]# yum install  -y pam* zlib*
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.163.com
 * epel: mirrors.aliyun.com
 * extras: mirrors.cn99.com
 * updates: mirrors.cn99.com
Package pam_yubico-2.26-1.el7.x86_64 already installed and latest version
Package pam_script-1.1.8-1.el7.x86_64 already installed and latest version
Package pam_oath-2.4.1-9.el7.x86_64 already installed and latest version
Package pam_snapper-0.2.8-4.el7.x86_64 already installed and latest version
Package pam_ssh_agent_auth-0.10.3-2.16.el7.x86_64 already installed and latest version
Package pam_2fa-1.0-1.el7.x86_64 already installed and latest version
Package pam_mapi-0.3.4-1.el7.x86_64 already installed and latest version
Package pam_ssh_user_auth-1.0-1.el7.x86_64 already installed and latest version
Package pam_mount-2.16-5.el7.x86_64 already installed and latest version
Package pam_radius-1.4.0-3.el7.x86_64 already installed and latest version
Package pamtester-0.1.2-4.el7.x86_64 already installed and latest version
Package pam_afs_session-2.6-5.el7.x86_64 already installed and latest version
Package pam_pkcs11-0.6.2-30.el7.x86_64 already installed and latest version
Package pam-1.1.8-22.el7.x86_64 already installed and latest version
Package pam_ssh-2.3-1.el7.x86_64 already installed and latest version
Package 1:pam_url-0.3.3-4.el7.x86_64 already installed and latest version
Package pam_wrapper-1.0.7-2.el7.x86_64 already installed and latest version
Package pam-kwallet-5.5.2-1.el7.x86_64 already installed and latest version
Package pam-devel-1.1.8-22.el7.x86_64 already installed and latest version
Package pam_krb5-2.4.8-6.el7.x86_64 already installed and latest version
Package zlib-devel-1.2.7-18.el7.x86_64 already installed and latest version
Package zlib-static-1.2.7-18.el7.x86_64 already installed and latest version
Package zlib-1.2.7-18.el7.x86_64 already installed and latest version
Package zlib-ada-1.4-0.5.20120830CVS.el7.x86_64 already installed and latest version
Package zlib-ada-devel-1.4-0.5.20120830CVS.el7.x86_64 already installed and latest version
Nothing to do
[root@linux-node3 ~]#

下载openssh包和openssl的包

我们都下载最新版本，下载箭头指的包

https://openbsd.hk/pub/OpenBSD/OpenSSH/portable/

https://ftp.openssl.org/source/

开始安装openssl

个人习惯把安装包或者工具之类的放下面目录。根据个人喜好随便放，不影响安装

[root@linux-node3 ~]# mkdir /data/tools -p
[root@linux-node3 ~]# cd /data/tools/
[root@linux-node3 /data/tools]# rz -E
rz waiting to receive.
[root@linux-node3 /data/tools]# ll
total 5224
-rw-r--r-- 1 root root 5348369 Apr 27 12:19 openssl-1.0.2r.tar.gz
 
 
 
解压文件
[root@linux-node3 /data/tools]# tar xfz openssl-1.0.2r.tar.gz
[root@linux-node3 /data/tools]# ll
total 5228
drwxr-xr-x 20 root root    4096 Apr 27 12:20 openssl-1.0.2r
-rw-r--r--  1 root root 5348369 Apr 27 12:19 openssl-1.0.2r.tar.gz
[root@linux-node3 /data/tools]# cd
[root@linux-node3 ~]#
 
 
现在是系统默认的版本，等会升级完毕对比下
[root@linux-node3 ~]# openssl version
OpenSSL 1.0.2k-fips  26 Jan 2017
[root@linux-node3 ~]#

备份下面2个文件或目录（如果存在的话就执行）

[root@linux-node3 ~]# ll /usr/bin/openssl
-rwxr-xr-x 1 root root 555248 Mar 12 18:12 /usr/bin/openssl
[root@linux-node3 ~]# mv /usr/bin/openssl /usr/bin/openssl_bak
 
[root@linux-node3 ~]# ll /usr/include/openssl
total 1864
-rw-r--r-- 1 root root   6146 Mar 12 18:12 aes.h
-rw-r--r-- 1 root root  63204 Mar 12 18:12 asn1.h
-rw-r--r-- 1 root root  24435 Mar 12 18:12 asn1_mac.h
-rw-r--r-- 1 root root  34475 Mar 12 18:12 asn1t.h
-rw-r--r-- 1 root root  38742 Mar 12 18:12 bio.h
-rw-r--r-- 1 root root   5351 Mar 12 18:12 blowfish.h
......
 
[root@linux-node3 ~]# mv /usr/include/openssl /usr/include/openssl_bak
[root@linux-node3 ~]#

编译安装新版本的openssl

配置、编译、安装3个命令一起执行

&&符号表示前面的执行成功才会执行后面的

[root@linux-node3 ~]# cd /data/tools/openssl-1.0.2r/
 
[root@linux-node3 /data/tools/openssl-1.0.2r]# ./config shared && make && make install

以上命令执行完毕，echo $?查看下最后的make install是否有报错，0表示没有问题

下面2个文件或者目录做软链接（刚才前面的步骤mv备份过原来的）

[root@linux-node3 ~]# ln -s /usr/local/ssl/bin/openssl /usr/bin/openssl
[root@linux-node3 ~]# ln -s /usr/local/ssl/include/openssl /usr/include/openssl
[root@linux-node3 ~]# ll /usr/bin/openssl
lrwxrwxrwx 1 root root 26 Apr 27 12:31 /usr/bin/openssl -> /usr/local/ssl/bin/openssl
[root@linux-node3 ~]# ll /usr/include/openssl -ld
lrwxrwxrwx 1 root root 30 Apr 27 12:31 /usr/include/openssl -> /usr/local/ssl/include/openssl
[root@linux-node3 ~]#

命令行执行下面2个命令加载新配置

echo "/usr/local/ssl/lib" >> /etc/ld.so.conf
 
/sbin/ldconfig

查看确认版本。没问题

[root@testssh ~]# openssl version
OpenSSL 1.0.2r  26 Feb 2019

安装openssh

上传openssh的tar包并解压

[root@testssh ~]# cd /data/tools/
[root@testssh tools]# ll
total 7628
-rw-r--r--  1 root root 1597697 Apr 18 07:02 openssh-8.0p1.tar.gz
drwxr-xr-x 20 root root    4096 Apr 23 23:12 openssl-1.0.2r
-rw-r--r--  1 root root 5348369 Feb 26 22:34 openssl-1.0.2r.tar.gz
-rwxr-xr-x  1 root root  853040 Apr 11  2018 sshd
[root@testssh tools]# tar xfz openssh-8.0p1.tar.gz
[root@testssh tools]# cd openssh-8.0p1
 
 
可能文件默认显示uid和gid数组都是1000，这里重新授权下。不授权可能也不影响安装（请自行测试）
[root@testssh tools]# chown -R root.root /data/tools/openssh-8.0p1

命令行删除原先ssh的配置文件和目录

然后配置、编译、安装

注意下面编译安装的命令是一行，请把第一行末尾的 \ 去掉，然后在文本里弄成一行之后放命令行执行

rm -rf /etc/ssh/*
 
./configure --prefix=/usr/ --sysconfdir=/etc/ssh  --with-openssl-includes=/usr/local/ssl/include \
 --with-ssl-dir=/usr/local/ssl   --with-zlib   --with-md5-passwords   --with-pam  && make && make install

参考下我的截图

安装完毕检查下结果

修改配置文件最终为如下内容，其他的不要动

[root@linux-node3 ~]# grep "^PermitRootLogin"  /etc/ssh/sshd_config
PermitRootLogin yes
[root@linux-node3 ~]# grep  "UseDNS"  /etc/ssh/sshd_config
UseDNS no
[root@linux-node3 ~]#

从原先的解压的包中拷贝一些文件到目标位置（如果目标目录存在就覆盖）

(可能下面的ssh.pam文件都没用到，因为sshd_config配置文件貌似没使用它，请自行测试。我这边是拷贝了)

[root@linux-node3 /data/tools/openssh-8.0p1]# cp -a contrib/redhat/sshd.init /etc/init.d/sshd
[root@linux-node3 /data/tools/openssh-8.0p1]# cp -a contrib/redhat/sshd.pam /etc/pam.d/sshd.pam
[root@linux-node3 /data/tools/openssh-8.0p1]# chmod +x /etc/init.d/sshd
 
[root@linux-node3 /data/tools/openssh-8.0p1]# chkconfig --add sshd
[root@linux-node3 /data/tools/openssh-8.0p1]# systemctl enable sshd
[root@linux-node3 /data/tools/openssh-8.0p1]#

把原先的systemd管理的sshd文件删除或者移走或者删除，不移走的话影响我们重启sshd服务

[root@linux-node3 ~]# mv  /usr/lib/systemd/system/sshd.service  /data/

设置sshd服务开机启动

[root@linux-node3 ~]# chkconfig sshd on
Note: Forwarding request to 'systemctl enable sshd.socket'.
Created symlink from /etc/systemd/system/sockets.target.wants/sshd.socket to /usr/lib/systemd/system/sshd.socket.

接下来测试启停服务。都正常

以后管理sshd通过下面方式了
[root@linux-node3 ~]# /etc/init.d/sshd restart
Restarting sshd (via systemctl):                           [  OK  ]
[root@linux-node3 ~]#
[root@linux-node3 ~]#
[root@linux-node3 ~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      31800/sshd         
tcp6       0      0 :::22                   :::*                    LISTEN      31800/sshd         
tcp6       0      0 :::23                   :::*                    LISTEN      1/systemd          
[root@linux-node3 ~]# /etc/init.d/sshd stop
Stopping sshd (via systemctl):                             [  OK  ]
[root@linux-node3 ~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp6       0      0 :::23                   :::*                    LISTEN      1/systemd          
[root@linux-node3 ~]# /etc/init.d/sshd start
Starting sshd (via systemctl):                            [  OK  ]
[root@linux-node3 ~]#
[root@linux-node3 ~]#

使用systemd方式也行

[root@linux-node3 ~]# systemctl stop sshd
[root@linux-node3 ~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp6       0      0 :::23                   :::*                    LISTEN      1/systemd          
[root@linux-node3 ~]# systemctl start sshd
[root@linux-node3 ~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      31958/sshd         
tcp6       0      0 :::22                   :::*                    LISTEN      31958/sshd         
tcp6       0      0 :::23                   :::*                    LISTEN      1/systemd          
[root@linux-node3 ~]# systemctl restart sshd
[root@linux-node3 ~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name   
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      31999/sshd         
tcp6       0      0 :::22                   :::*                    LISTEN      31999/sshd         
tcp6       0      0 :::23                   :::*                    LISTEN      1/systemd          
[root@linux-node3 ~]#

测试版本。都正常

[root@linux-node3 ~]# ssh -V
OpenSSH_8.0p1, OpenSSL 1.0.2r  26 Feb 2019
[root@linux-node3 ~]#
 
[root@linux-node3 ~]# telnet 127.0.0.1 22
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
SSH-2.0-OpenSSH_8.0

如果不是生产机器。可以试着重启机器测试下登录sshd是否正常。我这边测试都没问题

测试没问题后可以把telnet服务关闭了

[root@linux-node3 ~]# systemctl disable xinetd.service
Removed symlink /etc/systemd/system/multi-user.target.wants/xinetd.service.
[root@linux-node3 ~]# systemctl stop xinetd.service
[root@linux-node3 ~]# systemctl disable telnet.socket
[root@linux-node3 ~]# systemctl stop telnet.socket
[root@linux-node3 ~]# netstat -lntp

本文参考链接：

https://www.cnblogs.com/nmap/p/10779658.html
https://blog.csdn.net/f110300641/article/details/82758372

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Centos7如何升级openSSH

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