Increase the number of telnet sessions allowed

Q. I am using Fedora Linux and it act as telnet server for our University UNIX lab. We have total 250 computers. At a pick time more than 100 people try to connect server. Only 90 connections are allowed (configured by old admin). Now I want to take this limit to 300 connections or instances. How do I increase the number of telnet sessions allowed?

A. Under Fedora Linux (and old Red Hat Linux or RHEL) xinetd use to control telnet server. The eXtended InterNET Daemon, is an open-source daemon which runs on on many Unix systems and manages Internet-based connectivity. It offers a more secure extension to or version of inetd, the Internet daemon.

xinetd features access control mechanisms, extensive logging capabilities, and the ability to make services available based on time. It can place limits on the number of servers that the system can start, and has deployable defence mechanisms to protect against port scanners, among other things.

You need to edit /etc/xinetd.conf or /etc/xinetd.conf/telnet file and set instances = unlimited:# vi /etc/xinetd.confEdit instances line so that it should read as follows:instances = unlimitedORinstances = 300Restart the xinetd service:# /etc/init.d/xinetd restart

Posted by: SXI ADMIN

The author is the creator of SXI LLC and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.