1、查看是否安装telnet
rpm -qa|grep telnet
rpm -qa|grep xinetd
2、从别的系统上使用ftp或者scp进行拷贝telnet
ftp 135.191.27.195
mget telnet-server-0.17-47.el6_3.1.x86_64.rpm telnet-0.17-47.el6_3.1.x86_64.rpm
rpm -ivh xinetd-2.3.14-38.el6.x86_64.rpm
rpm -ivh telnet-0.17-47.el6_3.1.x86_64.rpm
rpm -ivh telnet-server-0.17-47.el6_3.1.x86_64.rpm
3、修改配置文件
(1)修改系统安全配置文件
mv /etc/securetty /etc/securetty.bak
(2)修改telnet配置文件
1.vi /etc/xinetd.d/telnet
将disable改为no
2.vi /etc/pam.d/login
将pam_securetty.so这一行加上注释
(3)重启Xinetd服务
service xinetd restart
(注：此时退出ssh登录协议，用telnet登录）
4.开始升级SSH服务 （保证此服务器上openssh-6.7p1.tar.gz openssl-1.0.1h.tar.gz zlib-1.2.8.tar.gz这三个tar包文件，如没有就用scp,ftp上传与下载）
service sshd stop
cp /etc/init.d/sshd /root/
rpm -e openssh --nodeps
rpm -e openssh-server --nodeps
rpm -e openssh-clients --nodeps
rpm -e openssh-askpass
chmod -R 777 *
cd /mnt
tar -zxvf zlib-1.2.8.tar.gz
cd zlib-1.2.8
./configure
make
make install
cd /mnt
tar -zxvf openssl-1.0.1h.tar.gz
cd openssl-1.0.1h
./config shared zlib
make
make install
mv /usr/bin/openssl /usr/bin/openssl.1FF
mv /usr/include/openssl /usr/include/openssl.1FF
ln -s /usr/local/ssl/bin/openssl /usr/bin/openssl
ln -s /usr/local/ssl/include/openssl /usr/include/openssl
echo "/usr/local/ssl/lib" >> /etc/ld.so.conf
/sbin/ldconfig -v
mv /etc/ssh /etc/ssh_bak
cd /mnt
tar -zxvf openssh-6.7p1.tar.gz
cd openssh-6.7p1
./configure --prefix=/usr --sysconfdir=/etc/ssh --with-zlib --with-ssl-dir=/usr/local/ssl --with-md5-passwords --mandir=/usr/share/man
make
make install
cp -p contrib/redhat/sshd.init /etc/init.d/sshd
chmod +x /etc/init.d/sshd
chkconfig --add sshd
cp sshd_config /etc/ssh/sshd_config
y
cp sshd /usr/sbin/sshd
y
5.重启SSH服务并检查版本是否有改变
service sshd restart
ssh -V
6.关闭telnet（参考前面打开telnet服务的步骤反之）
mv /etc/securetty.bak /etc/securetty
vi /etc/xinetd.d/telnet
vi /etc/pam.d/login
service xinetd restart