Can not log in as root via telnet when "ktelnet" service is enabled
This document (7007097) is provided subject to the disclaimer at the end of this document.
Environment
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 11 Service Pack 1
SUSE Linux Enterprise Server 11 Service Pack 1
Situation
You have followed TID 3485070 - How To Enable Root Login for Telnet to enable root login to the system via telnet. Yet, when trying to log in with the root user, you receive a message "login incorrect" and the login attempt fails. The telnet-server and the krb5-apps-servers packages are installed on the system. Both "telnet" and "ktelnet" services are enabled.
Resolution
The krb5-apps-servers package contains a telnet server, /usr/lib/mit/sbin/telnetd, which does not respect the /etc/securetty settings mentioned in TID 3485070.
At the same time, the krb5-apps-servers package contains a xinetd config file, /etc/xinetd.d/ktelnet, which declares itself as the handler for the telnet service. When xinetd reads its configuration at startup, /etc/xinetd.d/ktelnet takes precedence over /etc/xinetd.d/telnet, and therefore xinetd will launch the /usr/lib/mit/sbin/telnetd daemon after a telnet client connects to the server on TCP port 23, instead of launching /usr/sbin/in.telnetd.
To resolve this issue, edit the /etc/xinetd.d/ktelnet file and change the "service telnet" declaration on line 4 to "service ktelnet". After doing this change, run "rcxinetd restart". Now, the /etc/securetty aware /usr/sbin/in.telnetd daemon will be available on port 23, and the kerberized telnet daemon /usr/lib/mit/sbin/telnetd will be available on port 6623, which is the IANA Registered Port number[*] for this service. This configuration will allow you to log in as root via telnet to TCP port 23.
[*] http://www.iana.org/assignments/port-numbers
At the same time, the krb5-apps-servers package contains a xinetd config file, /etc/xinetd.d/ktelnet, which declares itself as the handler for the telnet service. When xinetd reads its configuration at startup, /etc/xinetd.d/ktelnet takes precedence over /etc/xinetd.d/telnet, and therefore xinetd will launch the /usr/lib/mit/sbin/telnetd daemon after a telnet client connects to the server on TCP port 23, instead of launching /usr/sbin/in.telnetd.
To resolve this issue, edit the /etc/xinetd.d/ktelnet file and change the "service telnet" declaration on line 4 to "service ktelnet". After doing this change, run "rcxinetd restart". Now, the /etc/securetty aware /usr/sbin/in.telnetd daemon will be available on port 23, and the kerberized telnet daemon /usr/lib/mit/sbin/telnetd will be available on port 6623, which is the IANA Registered Port number[*] for this service. This configuration will allow you to log in as root via telnet to TCP port 23.
[*] http://www.iana.org/assignments/port-numbers
Disclaimer
This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.
- Document ID:7007097
- Creation Date: 25-Oct-2010
- Modified Date:28-Sep-2022
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- SUSE Linux Enterprise Server
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