[root@localhost root]#rpm -qa telnet
telnet-0.17-25
//telnet.rpm是默认安装的//
[root@localhost root]#rpm -qa telnet-server
空
//telnet-server.rpm是默认没有安装的//
（2） 配置yum源
国内的两大门户网易和搜狐都有镜像服务器
下载repo文件
备份并替换系统的repo文件
[root@192 ~]# cd /etc/yum.repos.d/
[root@192 ~]# mv CentOS-Base.repo CentOS-Base.repo.bak
[root@192 ~]# mv /root/CentOS6-Base-163.repo CentOS-Base.repo
3. 执行yum源更新
[root@192 ~]# yum clean all
[root@192 ~]# yum makecache
[root@192 ~]# yum update
（3） 安装telnet-server
[root@192 ~]# yum install telnet-server
Loaded plugins: axelget, downloadonly, fastestmirror
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository addons is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Repository contrib is listed more than once in the configuration
Loading mirror speeds from cached hostfile
* addons: mirror.neu.edu.cn
* base: mirror.neu.edu.cn
* extras: mirror.neu.edu.cn
* updates: mirror.neu.edu.cn
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package telnet-server.i386 1:0.17-41.el5 set to be updated
--> Finished Dependency Resolution
Installing:
telnet-server i386 1:0.17-41.el5 base 35 k
Transaction Summary
===============================================================
Install 1 Package(s)
Upgrade 0 Package(s)
Total download size: 35 k
Is this ok [y/N]: y
Downloading Packages:
Package base download size 36202 less than 54000,Skip plugin!
telnet-server-0.17-41.el5.i386.rpm | 35 kB 00:03
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : telnet-server 1/1
Installed:
telnet-server.i386 1:0.17-41.el5
Complete!
（4） 在远端使用putty登陆
图 3.3使用Putty远程登录Linux
3.2.4 安装环境所需软件包
1.Dkms
2.kernel_ppp_mppe MPPE （Microsoft Point to Point Encryption，微软点对点加密）
3.ppp PPP（Point-to-Point Protocol，点到点协议）
4.pptpd
（1） 查看还需安装哪些软件，由于RHEL 5 的 2.6.18 内核已经集成了MPPE和高版本的ppp
[root@192 ~]# rpm -q ppp
ppp-2.4.4-9.0.rhel5
[root@192 ~]# strings '/usr/sbin/pppd'|grep -i mppe|wc -l
46
检查PPP是否支持MPPE,若结果显示“0”则表示不支持，而“30”或更大的数字就表示支持。 Linux系统下VPN的研究与部署实现(11):http://www.751com.cn/jisuanji/lunwen_9562.html