一、安裝配置telnet

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

? ?? [root@localhost ~]# cat > /etc/xinetd.d/telnet <<EOF

? ? ?service telnet {

????disable = no

????flags = REUSE

????socket_type = stream????

????wait = no

????user = root

????server = /usr/sbin/in.telnetd

????log_on_failure += USERID

????}

????EOF

????[root@localhost ~]# cat >> /etc/securetty <<EOF

????pts/0

????pts/1

????pts/2

????pts/3

????pts/4

????EOF

????[root@localhost ~]# systemctl enable xinetd --now

????[root@localhost ~]# systemctl enable telnet.socket --now

????[root@localhost ~]# ss -nltp | grep 23

????LISTEN? ? ?0? ? ? 64? ? ? ? [::]:23? ? ? ? ? ? ? ? ? ? [::]:*? ? ? ? ? ? ? ? ? ?users:(("xinetd",pid=1744,fd=5))

二、安裝openssh

[root@localhost ~]# yum remove openssh-server

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

[root@localhost openssh-8.8p1]# pwd

/tmp/openssh-8.8p1

[root@localhost openssh-8.8p1]# ./configure --prefix=/usr --sysconfdir=/etc/ssh --with-md5-passwords --with-pam

[root@localhost openssh-8.8p1]# echo $?

[root@localhost openssh-8.8p1]# make && make install

echo "UseDNS no" >> /etc/ssh/sshd_config

echo 'PermitRootLogin yes' >> /etc/ssh/sshd_config

echo 'PubkeyAuthentication yes' >> /etc/ssh/sshd_config

echo 'PasswordAuthentication yes' >> /etc/ssh/sshd_config

# if GUI

echo "X11Forwarding yes" >> /etc/ssh/sshd_config

echo "X11UseLocalhost no" >> /etc/ssh/sshd_config

echo "XAuthLocation /usr/bin/xauth" >> /etc/ssh/sshd_config

[root@localhost ssh]# ssh -V

OpenSSH_8.8p1, OpenSSL 1.0.2k-fips? 26 Jan 2017

[root@localhost redhat]# pwd

/tmp/openssh-8.8p1/contrib/redhat

[root@localhost redhat]# ls

gnome-ssh-askpass.csh? gnome-ssh-askpass.sh? openssh.spec? sshd.init? sshd.pam

[root@localhost redhat]# cp -a sshd.init /etc/init.d/sshd

[root@localhost redhat]# cp -a sshd.pam /etc/pam.d/sshd.pam

[root@localhost redhat]# cd /etc/ssh

[root@ykt01 ssh]# chmod 600 ssh_host_ecdsa_key ssh_host_ed25519_key ssh_host_rsa_key

[root@localhost ~]# chkconfig --add sshd

[root@localhost ~]# systemctl enable sshd --now

# 切換ssh登陸

[root@localhost ~]# systemctl disable xinetd.service --now

[root@localhost ~]# systemctl disable telnet.socket --now