Steps are as follows:
1, ready to work
1.1, download the relevant software packages
OpenSSH need to rely on ZLIB and OpenSSL, therefore you need to download the three source package from the official website. Note that: OpenSSH latest version 8.1p1 dependent OpenSSL version 1.0.2k, rather than the latest version 1.1.0e (use this upgrade version will fail), ZLIB can use the latest version 1.2.11. Three source code Download:
http://www.zlib.net/
http://www.openssl.org/
http://www.openssh.org/
1.2, view the current system software version
# rpm -q zlib
# openssl version
# ssh -V
1.3, configure yum online source
# cd /etc/yum.repos.d
# Rm -rf * # delete all current yum source files
# Wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo # source connected to Ali goes online
1.4, install and enable the telnet service
Because the process need to uninstall OpenSSH upgrade existing OpenSSH, so in order to maintain a remote connection to the server is available, you need to enable telnet services as an alternative, such as upgrading problems, it can also be rolled back through telnet login server.
A, install the telnet service
# yum -y install telnet-server*
B, enable telnet
Turn off the firewall, telnet or may not be connected
# service iptables stop
# chkconfig iptables off
# We /etc/xinetd.d/telnet
Yes which will disable read no field to enable telnet service
# mv / etc / securetty /etc/securetty.old # allow root user login through telnet
# /etc/init.d/xinetd start # start telnet service
# chkconfig xinetd on # enable telnet service start-up, after the upgrade process to avoid an unexpected restart the server can not remote login system
success enabled # telnet [ip] # new terminal to open a remote telnet login authentication
1.5, install the build kit
# yum -y install gcc pam-devel zlib-devel