编译环境

系统版本： CentOS 7
软件版本：

  • openssh-8.8p1.tar.gz
  • x11-ssh-askpass-1.2.4.1.tar.gz

编译 OpenSSH

  1. 依赖包
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yum install rpm-build zlib-devel openssl-devel gcc krb5-devel pam-devel libX11-devel libXt-devel gtk2-devel imake -y
  1. 创建编译目录
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mkdir -p /root/rpmbuild/{SOURCES,SPECS}
  1. 下载 openssh-8.8p1编译包和 x11-ssh-askpass 依赖包并解压修改配置

    https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-8.8p1.tar.gz

    https://src.fedoraproject.org/repo/pkgs/openssh/x11-ssh-askpass-1.2.4.1.tar.gz/8f2e41f3f7eaa8543a2440454637f3c3/x11-ssh-askpass-1.2.4.1.tar.gz

安装包上传至/root/rpmbuild/SOURCES目录下

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cd /root/rpmbuild/SOURCES
tar -zvxf openssh-8.8p1.tar.gz
cp openssh-8.8p1/contrib/redhat/openssh.spec  /root/rpmbuild/SPECS/

sed -i -e "s/%define no_x11_askpass 0/%define no_x11_askpass 1/g" /root/rpmbuild/SPECS/openssh.spec
sed -i -e "s/%define no_gnome_askpass 0/%define no_gnome_askpass 1/g" /root/rpmbuild/SPECS/openssh.spec
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vim /root/rpmbuild/SPECS/openssh.spec
# 注释掉 BuildRequires: openssl-devel < 1.1 这一行
  1. 开始编译
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rpmbuild -ba /root/rpmbuild/SPECS/openssh.spec

编译成功后 RPM 软件包存放在 /root/rpmbuild/RPMS/x86_64/ 目录下

image-20221130170410196

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cd /root/rpmbuild/RPMS/x86_64/ && ll

image-20221130170206509

安装 OpenSSH

前提条件

​ 必须使用多台物理机在不用网络环境下（有线连接和手机热点连接）打开多个SSH终端，避免因为网络中断安装失败，导致 SSH 连接不上主机。

​ 安装过程中不能断开当前 SSH 终端连接，必须在 OpenSSH 服务启动后并且测试新的 SSH 终端可以连接的情况下断开。否则主机将无法连接进入终端。

安装 OpenSSH

  1. 备份 PAM
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cp /etc/pam.d/sshd /etc/pam.d/sshd.bak

以下为 /etc/pam.d/sshd 内容备份

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#%PAM-1.0
auth       required     pam_sepermit.so
auth       substack     password-auth
auth       include      postlogin
# Used with polkit to reauthorize users in remote sessions
-auth      optional     pam_reauthorize.so prepare
account    required     pam_nologin.so
account    include      password-auth
password   include      password-auth
# pam_selinux.so close should be the first session rule
session    required     pam_selinux.so close
session    required     pam_loginuid.so
# pam_selinux.so open should only be followed by sessions to be executed in the user context
session    required     pam_selinux.so open env_params
session    required     pam_namespace.so
session    optional     pam_keyinit.so force revoke
session    include      password-auth
session    include      postlogin
# Used with polkit to reauthorize users in remote sessions
-session   optional     pam_reauthorize.so prepare
  1. 安装 OpenSSH RPM 软件包 （会自动处理依赖关系）
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cd /root/rpmbuild/RPMS/x86_64/
yum install openssh-8.8p1-1.el7.x86_64.rpm  openssh-clients-8.8p1-1.el7.x86_64.rpm openssh-server-8.8p1-1.el7.x86_64.rpm
  1. 允许 Root 用户登录

注意检查 /etc/ssh/sshd_config 中是否启用Root登录密码登录

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PasswordAuthentication yes
PermitRootLogin yes
  1. 给予权限
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cd /etc/ssh
chmod 600 ssh_host_ecdsa_key ssh_host_ed25519_key ssh_host_rsa_key
  1. 恢复 PAM
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cp /etc/pam.d/sshd.bak /etc/pam.d/sshd
  1. 重启 OpenSSH 并检查启动状态
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ssh -V
systemctl daemon-reload
systemctl restart sshd
systemctl status sshd
systemctl enable sshd

image-20221130171218520

至此，升级完成，先别关闭当前SSH终端，直接新开一个终端，连接到服务器测试。

降级 OpenSSH

正常情况下，降级是不会覆盖 /etc/pam.d/sshd 和 vi /etc/ssh/sshd_config , 但保险起见还是对文件进行备份检查。

  1. 备份 PAM
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cp /etc/pam.d/sshd /etc/pam.d/sshd.bak2
  1. 降级
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yum downgrade openssh openssh-clients openssh-server
  1. 检查配置文件
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vi /etc/ssh/sshd_config

PermitRootLogin yes
PasswordAuthentication yes
  1. 检查 PAM 如果被修改则恢复
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cat /etc/pam.d/sshd

image-20221130171319866

  1. 重启服务
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ssh -V
systemctl daemon-reload
systemctl restart sshd
systemctl status sshd
systemctl enable sshd

至此，降级完成，先别关闭当前SSH终端，直接新开一个终端，连接到服务器测试。

编译安装 OpenSSL3.0.7

官方下载地址: https://www.openssl.org/source/openssl-3.0.7.tar.gz

  1. 安装依赖包
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yum install perl-IPC-Cmd perl-Data-Dumper
  1. 解压源码包
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tar -zvxf openssl-3.0.7.tar.gz
  1. 配置
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cd openssl-3.0.7
./config

image-20221208144603419

  1. 安装
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make
make install
  1. 更换 openssl
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# 备份 openssl
mv /usr/bin/openssl /usr/bin/openssl.old
mv /usr/lib64/openssl /usr/lib64/openssl.old

# 链接新版 openssl
ln -s /usr/local/bin/openssl /usr/bin/openssl
ln -s /usr/local/include/openssl/ /usr/include/openssl
  1. 更新动态链接库数据
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echo "/usr/local/lib/" >> /etc/ld.so.conf
echo "/usr/local/lib64/" >> /etc/ld.so.conf
# 重新加载动态链接库
ldconfig -v
  1. 更新完成
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openssl version -a

image-20221208151255143

降级 OpenSSL

  1. 恢复 OpenSSL 可执行文件
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mv /usr/bin/openssl.old /usr/bin/openssl
mv /usr/lib64/openssl.old /usr/lib64/openssl
  1. 删除遗留文件
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rm /usr/local/bin/openssl
rm -r /usr/local/ssl
rm -r /usr/local/include/openssl
rm -r /usr/local/lib64/engines-3
  1. 重新安装 OpenSSL1.0.2
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yum reinstall openssl openssl-libs -y

image-20221208165433853