Enable the root permission telnet for centos

Telnet: provides the telnet service, which is verified by unencrypted user/password groups and is attached to the xinetd service. The file is located in/etc/xinetd. d/telnet. Krb5-telnet: provides telnet service, allows normal telnet login, default is not allow root user login, use os5 authentication, attached to the xinetd service. & 3 different telnet methods:
Telnet: provides the telnet service, which uses unencrypted user/password groups for verification and is attached to the xinetd service. The file is located in/etc/xinetd. d/telnet.
Krb5-telnet: provides telnet service, allows normal telnet login, default is not allow root user login, use os5 authentication, attached to the xinetd service.
The file is located at/etc/xinetd. d/krb5-telnet.
Ekrb5-telnet: provides encrypted telnet service, but requires an encrypted server of ekrb5. The file is located at/etc/xinetd. d/ekrb5-telnet.

Enabling krb5-telnet allows normal telnet, but root does not allow direct login, resulting in the root of the write system command is not available

Enable the common telnet service:
1. redhat is not installed with the common telnet service. you can install it on your own.
Rpm-ivh telnet-server-0.17-38.el5.i386.rpm

2. the configuration file vim/etc/xinetd. d/telnet
Modify disable = no
/Etc/pam. d/login
Note out # auth [user_unknown = ignore success = OK ignore = ignore default = bad] pam_securetty.so

Number of consoles
/Etc/securetty
Pts/1
...

3. restart the service
Open telnet service
Chkconfig telnet on
Restart the daemon
Service xinetd restart
OR/etc/inet. d/xinetd restart