2、gdm配置

尝试以下方法：

一般情况执行以上命令就可以连接，包括root账户，如果root账户不能登录，别的账号可以登录的话请执行以下操作。
    # vi /usr/share/gdm/defaults.conf
  [security]
# Allow root to login.  It makes sense to turn this off for kiosk use, when
# you want to minimize the possibility of break in.
AllowRoot=true
# Allow login as root via XDMCP.  This value will be overridden and set to
# false if the /etc/default/login file exists and contains
# "CONSOLE=/dev/login", and set to true if the /etc/default/login file exists
# and contains any other value or no value for CONSOLE.
AllowRemoteRoot=true
# This will allow remote timed login.
AllowRemoteAutoLogin=false
# 0 is the most restrictive, 1 allo
  
  
#vi /etc/securetty
......
tty2
tty3
tty4
tty5
tty6
tty7
tty8
tty9
tty10
tty11
pts/0
pts/1
pts/2
pts/3
pts/4
  添加这一些。
  
  
# vi /etc/pam.d/login

  #%PAM-1.0
#auth [user_unknown=ignore success=ok ignore=ignore default=bad] pam_securetty.so
auth       include      system-auth
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    include      system-auth
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    optional     pam_keyinit.so force revoke
~
  
#vi  /etc/pam.d/remote
  
#%PAM-1.0
#auth       required     pam_securetty.so
auth       include      system-auth
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    include      system-auth
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    optional     pam_keyinit.so force revoke
~
~
  
#vi /etc/xinetd.d/krb5-telnet           //or telnet

# default: on
# description: The telnet server serves telnet sessions; it uses \
#       unencrypted username/password pairs for authentication.
service telnet
{        

        disable         = no 
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
}

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还可以尝试：

a、配置文件位置：/etc/gdm/custom.conf

增加配置选项：

[xdmcp]段下

Enable=true 

b、或图形界面下,运行gdmsetup，修改安全设置，允许root远程访问就可以了。