December 2005
Beginner
480 pages
13h 27m
English
Content preview from Linux Server Hacks, Volume TwoBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Hack #3. Deny All Access in One Second or Less
Here's a safe way to keep out all users while doing temporary maintenance or troubleshooting.
All administrators eventually need to have a machine running in full multiuser mode, with all services running, but at the same time completely deny login access to the machine. This is usually for the purpose of troubleshooting a problem, testing a new software installation, or performing maintenance or software upgrades. There are a couple of really quick ways to do this.
The first method is by far the quickest. Just run the following command (as root):
# touch /etc/nologinThis will deny access to anyone trying to log in to the machine. You'll want to be sure to keep an active login session on the machine after you create this file or make sure that root is allowed to log in on the local console or via SSH, since a root login will bypass this mechanism. You'll know it's working because the logs for some services will tell you that access was denied because of the presence of the nologin file. Others will just say "failed password."
This method can be improved through the use of a nologin.txt file, where you can put some text that users will see when they try to log in. If you have a scheduled downtime, for instance, you can put the details into this file so that users will get a friendly reminder that the machine is unavailable during the downtime window.
The second method works only if the services you're running are linked against libwrap ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.