引用:http://www.qqread.com/linux/2008/03/e401966.html
1、確定你的telnet服務打開沒有：
[root@111 ~]# chkconfig --list|grep telnet
ekrb5-telnet: off
krb5-telnet: off
[root@111 ~]#
注意檢查結果這裡是關閉狀態
2、打開telnet服務：
[root@111 ~]# chkconfig krb5-telnet on
[root@111 ~]# chkconfig --list|grep telnet
ekrb5-telnet: offv
krb5-telnet: on
[root@111 ~]#
檢查已經被打開了
3、修改登陸文件securetty,主要增加要登陸的終端點
[root@111 ~]# vi /etc/securetty
增加如下幾行：
pts/1
pts/2
pts/3
pts/4
pts/5
……
保存退出即可。
如果是chkconfig krb5-telnet on
會提示Unencrypted connection refused. Goodbye.Connection closed by foreign host.看錯誤信息好像是說的為加密的連接被拒絕，查看了他的配置文件也沒發現有什麼關於加密的選項，而且配置文件也很正確，於是到google上去搜索了一大圈，最後終於找到一個老外寫的一個解決方法：
I really needed a bit of guidance and you provided it./sbin/chkconfig --list |grep telnetThe above command told me I had both krb5-telnet and ekrb5-telnet, andalso the installed telnet all on. Initially I did not know what theywere all for. After turning them on and off and testing my telnetconnection from another box I realised that "ekrb5-telnet" was theencrypted telnet server that I needed to turn off to run "krb-telnet"which allowed non-encrypted telnet connections.eg /sbin/chkconfig ekrb5-telnet off
原來ekrb5-telnet是一個需要加密的telnet服務，把這個服務啟動上當然就需要加密了。解決方法：將/etc/xinetd.d/ekrb5-telnet裡面的disable改成=yes，再重啟xinetd服務service xinetd restart就OK了！
