telnet安装以及telnet(密码正确)无法登录！

telnet安装以及telnet(密码正确)无法登录！

1.telnet下载

先在yum源当中查找是否有这两个安装包

test login: Connection closed by foreign host.
[[email protected] xinetd.d]# yum list | grep telnet
telnet.x86_64                            1:0.17-66.el7                 @updates 
telnet-server.x86_64                     1:0.17-66.el7                 @updates 
[[email protected] xinetd.d]# 

如上述我们查到了有两个安装包

2.安装telnet

[[email protected] xinetd.d]# yum -y install telnet

[[email protected] xinetd.d]# yum -y install telnet-server

3.telnet安装成功之后我们启动telnet

由于telnet下载默认是存放在xinetd当中，但是我们启动xinetd发现没有这个依赖包。

[[email protected] xinetd.d]# service xinetd start
Redirecting to /bin/systemctl start xinetd.service
Failed to start xinetd.service: Unit not found.
[[email protected] xinetd.d]# 

4.下载xinetd，并重启xinetd

[[email protected] xinetd.d]# yum -y install xinetd

[[email protected] xinetd.d]# service xinetd start         //启动成功
Redirecting to /bin/systemctl start xinetd.service
[[email protected] xinetd.d]# 
[[email protected] xinetd.d]# ls /etc/xinetd.d/        //但是我们查看发现并没有telnet，所以我们要自己创建
chargen-dgram   daytime-dgram   discard-dgram   echo-dgram   tcpmux-server  time-dgram
chargen-stream  daytime-stream  discard-stream  echo-stream  telnet         time-stream
[[email protected] xinetd.d]# 

5.创建telnet，并且写入文本内容

注意的是，这文本里的第一行disable中的yes要改成no

[[email protected] xinetd.d]# cd /etc/xinetd.d/
[[email protected] xinetd.d]# vi telnet
[[email protected] xinetd.d]# cat  telnet
service telnet
{
        disable = no
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
 
}
[[email protected] xinetd.d]# 

查看一下端口号

[[email protected] xinetd.d]# netstat -tnl grep 23   //telnet默认端口23，下面已查出telnet端口号
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN     
tcp6       0      0 :::22                   :::*                    LISTEN     
tcp6       0      0 :::23                   :::*                    LISTEN     
tcp6       0      0 ::1:25                  :::*                    LISTEN     
[[email protected] xinetd.d]# 

在此telnet就以及配置完成了。

6.telnet（密码正确）无法登录

在这里我们telnet但是如果用户密码正确，还是不能登录，那么我们可以直接ssh连接进去进行配置更改

[[email protected] ~]# cat /etc/pam.d/login       //注意这里将第二行auth [...注释掉，然后保存退出
#%PAM-1.0
#auth [user_unknown=ignore success=ok ignore=ignore default=bad] pam_securetty.so
auth       substack     system-auth
auth       include      postlogin
account    required     pam_nologin.so
account    include      system-auth
password   include      system-auth
# pam_selinux.so close should be the first session rule
session    required     pam_selinux.so close
session    required     pam_loginuid.so
session    optional     pam_console.so
# pam_selinux.so open should only be followed by sessions to be executed in the user context
session    required     pam_selinux.so open
session    required     pam_namespace.so
session    optional     pam_keyinit.so force revoke
session    include      system-auth
session    include      postlogin
-session   optional     pam_ck_connector.so
[[email protected] ~]# 

7.重启telnet

[[email protected] ~]# service xinetd restart
Redirecting to /bin/systemctl restart xinetd.service
[[email protected] ~]# 

8.添加pts/0并重启

默认情况下linux都是认为pts0是不安全的连接，所以会拒绝掉，那么我可以放行pts0，在这里拉菲不介绍太多，如果要问怎么看，可以去/var/log/securre里面查询是那个被拒绝掉了霍。。。。

[[email protected] ~]# cat /etc/securetty      //进入这个文件，在最后一行添加pts/0
console
vc/1
vc/2
略。。。。。
pts/0
[[email protected] ~]# 

重启xinetd

[[email protected] ~]# service xinetd restart
Redirecting to /bin/systemctl restart xinetd.service
[[email protected] ~]# 

重启完就可以再连接，输入用户和密码就可以进去啦！！！

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