mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
vim /etc/yum.repos.d/CentOS-Base.repo
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$releasever - Base
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
yum clean all
yum makecache
yum install telnet-server xinetd -y
systemctl start telnet.socket
systemctl start xinetd
mv /etc/securetty /etc/securetty.bak
yum remove openssh -y
yum install -y gcc openssl-devel pam-devel rpm-build *libcrypto*
tar xf openssh-8.3p1.tar.gz
cd openssh-8.3p1
chmod 600 /etc/ssh/ssh_host_rsa_key
chmod 600 /etc/ssh/ssh_host_ecdsa_key
chmod 600 /etc/ssh/ssh_host_ed25519_key
./configure --prefix=/usr/ --sysconfdir=/etc/ssh/ --with-ssl --with-md5-passwords mandir=/usr/share/man/
make && make install
cp contrib/redhat/sshd.init /etc/init.d/sshd
echo 'PermitRootLogin yes' >> /etc/ssh/sshd_config
chkconfig sshd on
systemctl start sshd
systemctl enable sshd
systemctl restart sshd
systemctl stop telnet.socket
systemctl stop xinetd
systemctl disable telnet.socket
systemctl disable xinetd
ssh -V