The configuration method of the Ubuntu Telnet Server _linux

1. First introduce the daemon in Linux

The Linux system has a special daemon inetd (Internet Services Daemon), which is used for Internet standard services and is typically started when the system starts. The inetd configuration file can be given by the command line, which lists the services provided by inetd. If a configuration file is not given on the command line, INETD will read its configuration information from the file/etc/inetd.conf. The primary task of inetd is to listen for requests for server processes that are not started when the system is initialized, to listen for requests on TCP or UDP ports that are associated with services listed in the configuration file, and to start the corresponding server process when a request arrives at these protocol ports. inetd When a request reaches a service port managed by inetd, inetd forwards the request to a program named TCPD. TCPD based on the configuration file Host.{allow,deny} to determine whether the service is allowed to the request. If the request is allowed just the appropriate server program (such as: FTPD, Telnet) will be started. This mechanism is also known as Tcp_wrapper.

XINETD (exended InterNET Services Daemon) provides functionality similar to Inetd+tcp_wrapper, but is more powerful and secure. The commercial systems of mainstream Linux publishers such as red flags have gradually replaced inetd with xinetd, and provide access control, enhanced logging and resource management capabilities, and become the Internet Standard Super daemon for Linux systems. Many system services use xinetd such as FTP, IMAP, Pop, and Telnet. When all the services in the/etc/services access the server through their ports, the XINETD handles it first, before invoking the service request, XINETD first verifies that the requester satisfies the access control rules specified in the configuration file and that the current access exceeds the number of concurrent accesses specified. There are other rules specified in the configuration file, such as check through, xinetd the request to the corresponding service to deal with, they enter the sleep state, waiting for the next request processing.

2. Installation software

1, $sudo apt-get install xinetd telnetd

2, $sudo vim/etc/inetd.conf and add the following line:

Telnet Stream TCP nowait telnetd/usr/sbin/tcpd/usr/sbin/in.telnetd

3, $sudo vim/etc/xinetd.conf and add the following content:

# Simple configuration file for xinetd 
# Some defaults, and include/etc/xinetd.d/ 
defaults 
{ 
# E that you need a log_type line to is able to use Log_on_success 
# and Log_on_failure. The default is the following: 
# log_type = syslog Daemon Info 
instances = 
Log_type = syslog Authpriv 
log_on_success = Host PID 
log_on_failure = host 
cps = 
} 

4, $sudo vim/etc/xinetd.d/telnet and add the following content:

# default:on 
# description:the telnet Server serves Telnet sessions;it uses 
# unencrypted Username/password pair s for authentication. 
Service Telnet 
{ 
disable = no 
flags = reuse 
Socket_type = stream wait 
= no 
user = root 
serve r =/usr/sbin/in.telnetd 
log_on_failure + + USERID 
}

5, restart the machine or restart the network service $sudo/etc/init.d/xinetd restart

6, test configuration is successful (can be logged through the Telent server to Ubuntu is successful)

Method One: Login using Telnet client remote (Putty login tool, etc.)

Method Two: XP DOS (that is, start → run →cmd), enter Telnet, then open Ubuntu IP address (for example: Open 192.168.7.106)

The above is a small set to introduce the Ubuntu under the Telnet Server configuration method, I hope to help you, if you have any questions please give me a message, small series will promptly reply to everyone. Here also thank you very much for the cloud Habitat Community website support!