安装telnet-server发现yum代理问题

一 问题如下:

[root@Ben tech]# yum install xinetd

Loading "installonlyn" plugin
Setting up Install Process
Setting up repositories
core                                                                 [1/4]
Cannot find a valid baseurl for repo: core
Error: Cannot find a valid baseurl for repo: core

安装telnet-server发现yum问题, 最初认为是repo出了问题, 查找error: cannot find a valid baseurl for repo:core, 通过网络查找, 没有什么问题.比较adsl上网同实验室上网的差异, 觉得可能是由于proxy服务器的原因.

通过google查 yum proxy problem得如下问题解
Re: Yum proxy problem

--------------------------------------------------------------------------------

From: Jeff Vian <jvian10@xxxxxxxxxxx>
Date: Sun, 19 Mar 2006 11:44:35 -0600

--------------------------------------------------------------------------------
On Sun, 2006-03-19 at 22:41 +0530, Sumeet Pal Singh wrote:

Hi
I installed FC4 and tried to configure yum to work. I am behind a
proxy server which requires authentication.
My /etc/yum.conf file is

[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
distroverpkg=redhat-release
tolerant=1
exactarch=1
retries=20
obsoletes=1
gpgcheck=0

# The proxy server - proxy server:port number
proxy=http://vsnlproxy.iitk.ac.in:3128/
# The account details for yum connections
proxy_username=spsingh
proxy_password=password

I had a password with % in it. When trying yum update I got HTTP Error
407 ie proxy authentication required. When i tried to search for the
problem on net, I came across this
http://beau.org/pipermail/whitebox-users/2004-March/000781.html
which shows that the guy had problem connecting because of special
character which yum could not understand/encrypt.
I did the same.Changed my password so that it had alphanumeric only
and yum worked!!!!!
Wget, apt (on ubuntu5.10 and FC4) used to work with old password.
Is this a problem with yum. Can someone please test it out!! Also can
I submit it as bug?

Not a problem but a design of the program.
% is a special character to the shell and it must be escaped so it is
passed literally or not used in most of these circumstances.

 

I had same problem while installing gentoo previous month. it did not
emerge and finally I gave up the installation. Can someone please test
this and let me know. i will appreciate it. My email id is
sumeetpalsingh@xxxxxxxxx

Thanks in Advance.

 

----------------------------------------------------------------

解决代理问题后, 就可以根据鳥哥的 Linux 私房菜遠端連線伺服器 Telnet / SSH / VNC / XDMCP / RSH
http://202.43.217.123/search/cache.html?ei=UTF-8&icp=1&u=linux.vbird.org/linux_server/0310telnetssh.php&w=sftp&d=Lo7ztxIeOTVE&s=5285d9a3c1937841c2e0862829b55784
 来配置安装telnet-server了.

终于搞定. 虽然ssh安全可靠,但netterm的界面明显比putty好看, 感觉上更好. 所以还是配上玩玩, 再个xinetd上以前不是挂了很多服务的吗?慢慢玩吧, 可能service 的配置更集中, 好管理吧.

最后还是再推荐一下"鳥哥的 Linux 私房菜:"写得太好了.

二、启动telnet服务(转自http://www.51cto.com/art/200510/6020.htm)

1、开启服务

方法一：使用ntsysv,在出现的窗口之中，将 telnet前面*加上，然后按下 OK 。

方法二：编辑 /etc/xinetd.d/telnet

[root@wljs root]# vi /etc/xinetd.d/telnet

找到 disable = yes 将 yes 改成 no 。

2、激活服务

[root@wljs root]# service xinetd restart
 

三、测试服务

[root@wljs root]#telnet ip(或者hostname）
 

如果配置正确，系统提示输入远程机器的用户名和密码

Login:

Password:
 

注：默认只允许普通用户

四、设置telnet端口

#vi /etc/services

进入编辑模式后查找telnet(vi编辑方式下输入/telnet)

会找到如下内容：

telnet 23/tcp

telnet 23/udp
 

将23修改成未使用的端口号(如：2000)，退出vi，重启telnet服务，telnet默认端口号就被修改了。

五、Telnet服务限制

telnet是明文传送口令和数据的，如果你对其默认的设置不满意，有必要对其服务范围进行限制。假设你

的主机的ip是210.45.160.17，就可以按如下方式设置了，^_^!

#vi /etc/xinetd.d/telnet

service telnet

{

disable = no #激活 telnet 服务,no

bind = 210.45.160.17 #your ip

only_from = 210.45.0.0/16 #只允许 210.45.0.0 ~ 210.45.255.255 这个网段进入

only_from = .edu.cn #只有教育网才能进入！

no_access = 210.45.160.{115,116} #这两个ip不可登陆

access_times= 8:00-12:00 20:00-23:59 # 每天只有这两个时间段开放服务

......

}
 

六、Telnet root用户的登入

telnet 不是很安全，默认的情况之下不允许 root 以 telnet 进入 Linux 主机 。若要允许root用户登

入，可用下列方法：

[root @wljs /root]# vi /etc/pam.d/login

#auth required pam_securetty.so #将这一行加上注释！

或

[root@wljs root]# mv /etc/securetty /etc/securetty.bak

这样， root 就可以直接进入 Linux 主机了。不过，建议不要这样做。也可以在普通用户进入后，切换

到root用户,拥有root的权限。