Centos7 OpenSSH漏洞整改-蒲公英云

OpenSSHow漏洞风险提示，因此需要进行升级整改

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一、安装telnet(以防升级失败，ssh连不上服务器)

1、查看是否已经安装telnet服务

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

2、yum安装

[root@localhost ~]# yum -y install telnet* 
[root@localhost ~]# yum -y install xinetd

3、启动telnet服务并设置自动启动

[root@localhost ~]# systemctl enable xinetd.service
[root@localhost ~]# systemctl start  xinetd.service
[root@localhost ~]# systemctl enable telnet.socket
[root@localhost ~]# systemctl start  telnet.socket

4、添加

#在文本最后添加
[root@localhost ~]# vi /etc/securetty 
pts/0
pts/1
pts/2
#查看
[root@localhost ~]# tail -3 /etc/securetty 
pts/0
pts/1
pts/2

5、重启服务并查看端口

[root@localhost ~]# systemctl restart xinetd
[root@localhost ~]# ss -ntlp|grep 23
LISTEN     0      128         :::23                      :::*                   users:(("systemd",pid=1,fd=43))

二、升级OpenSSl

1、查看系统原版本

[root@localhost ~]# openssl version
OpenSSL 1.0.2k-fips  26 Jan 2017

2、下载https://ftp.openssl.org/source/

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3、安装依赖包

[root@localhost ~]# yum install -y gcc gcc-c++ glibc make autoconf openssl openssl-devel pcre-devel pam-devel pam* zlib*

4、解压

[root@localhost ~]# tar zxvf openssl-1.1.1k.tar.gz

5、检测环境

[root@localhost ~]# cd openssl-1.1.1k
[root@localhost openssl-1.1.1k]# ./config --prefix=/usr/local/openssl

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6、编译并安装

[root@localhost openssl-1.1.1k]# make && make install

7、替换当前系统的旧版本openssl(先保存原来的)

[root@localhost openssl-1.1.1k]# which openssl
/usr/bin/openssl
[root@localhost openssl-1.1.1k]# mv /usr/bin/openssl /usr/bin/openssl.old
[root@localhost openssl-1.1.1k]# mv /usr/lib64/openssl /usr/lib64/openssl.old
[root@localhost openssl-1.1.1k]# mv /usr/lib64/libssl.so /usr/lib64/libssl.so.old
[root@localhost openssl-1.1.1k]# ln -s /usr/local/openssl/bin/openssl /usr/bin/openssl
[root@localhost openssl-1.1.1k]# ln -s /usr/local/openssl/include/openssl /usr/include/openssl
[root@localhost openssl-1.1.1k]# ln -s /usr/local/openssl/lib/libssl.so /usr/lib64/libssl.so
[root@localhost openssl-1.1.1k]# echo "/usr/local/openssl/lib" >> /etc/ld.so.conf
[root@localhost openssl-1.1.1k]# ldconfig -v

8、确认版本

三、升级openssh

1、查看系统原版本

[root@localhost ~]# ssh -V
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017

2、下载https://openbsd.hk/pub/OpenBSD/OpenSSH/portable/

3、解压

[root@localhost ~]# tar zxvf openssh-8.6p1.tar.gz

4、移除旧版本

#移除之后，不能退出当前终端。若退出，只能通过telnet连接
[root@localhost ~]# mv /etc/ssh /etc/ssh.old

5、编译并安装

[root@localhost ~]# cd openssh-8.6p1
[root@localhost openssh-8.6p1]# ./configure --prefix=/usr/local/openssh --sysconfdir=/etc/ssh --with-pam --with-ssl-dir=/usr/local/openssl --with-md5-passwords --mandir=/usr/share/man --with-zlib=/usr/local/zlib --without-hardening
[root@localhost openssh-8.6p1]# make && make install

6、修改启动脚本

#拷贝启动脚本
[root@localhost openssh-8.6p1]# cp ./contrib/redhat/sshd.init /etc/init.d/sshd
#修改启动脚本
[root@localhost openssh-8.6p1]# vi /etc/init.d/sshd
#按如下图修改,需要注意，此路径是你安装新版本的openssh路径，根据你的实际情况修改
SSHD=/usr/local/openssh/sbin/sshd

7、修改sshd配置文件/etc/ssh/sshd_config

#直接用root登录终端（此处根据自身情况考虑）
[root@localhost openssh-8.6p1]# echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
#设置是否允许X11转发
[root@localhost openssh-8.6p1]# echo 'X11Forwarding yes' >> /etc/ssh/sshd_config
#是否允许密码验证
[root@localhost openssh-8.6p1]# echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config

8、卸载原有ssh（先安装后卸载，也是怕升级失败）

for i in  $(rpm -qa |grep openssh);do rpm -e $i --nodeps ;done

提示告警

将警告中被修改的文件名字再改回来

[root@localhost ~]# mv /etc/ssh/ssh_config.rpmsave /etc/ssh/ssh_config
[root@localhost ~]# mv /etc/ssh/sshd_config.rpmsave /etc/ssh/sshd_config
[root@localhost ~]# mv /etc/ssh/moduli.rpmsave /etc/ssh/moduli

9、替换相关命令，并重启sshd服务

[root@localhost ~]# cp -arp /usr/local/openssh/bin/* /usr/bin/
[root@localhost ~]# systemctl restart sshd

10、验证升级版本

11、设置开机启动

[root@localhost ~]# systemctl enable sshd

12、ssh正常登陆之后为了系统安全，需要停用telnet服务

[root@localhost ~]# systemctl stop xinetd
[root@localhost ~]# systemctl disable  xinetd
[root@localhost ~]# systemctl stop telnet.socket
[root@localhost ~]# systemctl disable  telnet.socket

四、隐藏openssh版本号

修改ssh默认端口之后，版本号也想隐藏

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1、（重点）要在执行编译步骤之前修改version.h文件

[root@localhost ~]# cd openssh-8.6p1
[root@localhost openssh-8.6p1]# vi version.h 
/* $OpenBSD: version.h,v 1.90 2021/04/16 03:42:00 djm Exp $ */
#define SSH_VERSION     "OpenSSH_8.6"
#define SSH_PORTABLE    "p1"
#define SSH_RELEASE     SSH_VERSION SSH_PORTABLE