Getting Started with the Linux Intrusion Detection System
This article assumes that you have installed LIDS and its associated administration tools.
We will set up a system with tight security settings, and the services that will be allowed to run are MySQL, Apache and Bind.
The sample commands below assume that the Apache installation resides in /usr/local/apache, with a log directory of /var/log/httpd, and also assumes your Apache configuration directory is /etc/httpd. MySQL is assumed to be installed in /usr/local/mysql. Obviously, you'll want to change the commands to suit your installation if it differs.
It is beyond the scope of this article to cover everything necessary to secure your system completely. However, these examples of how access control is administered in LIDS should get you started.
After you restart LIDS, you can begin adding access controls to various system binaries and libraries. The following sets the /sbin, /bin, /usr/bin and /lib to read-only:
lidsconf -A -o /sbin -j READONLY lidsconf -A -o /bin -j READONLY lidsconf -A -o /usr/bin -j READONLY lidsconf -A -o /lib -j READONLY
Next, we define some additional access controls for /opt, /etc and /usr/local/etc, which should be read-only, and we deny all access to /etc/shadow and the boot manager file:
lidsconf -A -o /etc -j READONLY lidsconf -A -o /usr/local/etc -j READONLY lidsconf -A -o /etc/shadow -j DENY lidsconf -A -o /etc/lilo.conf -j DENY
Because we have denied all access to /etc/shadow, the system will not be able to authenticate logins, thus we need to allow login and vlock to have read-only access to the file. Additionally, su also should have read-only access to the /etc/shadow file:
lidsconf -A -s /bin/login -o /etc/shadow -j READONLY lidsconf -A -s /usr/bin/vlock -o /etc/shadow -j READONLY lidsconf -A -s /bin/su -o /etc/shadow -j READONLY
We need to set some other access controls for su, in order for it to work with UIDs and GIDs, and access the /etc/shadow file:
lidsconf -A -s /bin/su -o CAP_SETUID -j GRANT lidsconf -A -s /bin/su -o CAP_SETGID -j GRANT lidsconf -A -s /bin/su -o /etc/shadow -j READONLY
Now, we need to allow init, login and associated applications to have write access to log files:
lidsconf -A -o /var/log -j APPEND lidsconf -A -s /bin/login -o /var/log/wtmp -j WRITE lidsconf -A -s /bin/login -o /var/log/lastlog -j WRITE lidsconf -A -s /sbin/init -o /var/log/wtmp -j WRITE lidsconf -A -s /sbin/init -o /var/log/lastlog -j WRITE lidsconf -A -s /sbin/halt -o /var/log/wtmp -j WRITE lidsconf -A -s /sbin/halt -o /var/log/lastlog -j WRITE lidsconf -A -s /etc/rc.d/rc.sysinit -o /var/log/wtmp -i 1 -j WRITE lidsconf -A -s /etc/rc.d/rc.sysinit -o /var/log/lastlog -i 1 -j WRITE
Now, we set up access control for root's home folder. We allow only the bash history file to be appended:
f -A -o /root -j READONLY lidsconf -A -s /bin/bash -o /root/.bash_history -j APPEND
Finally, we allow the init program to kill processes on shutdown:
lidsconf -A -s /sbin/init -o CAP_INIT_KILL -j GRANT lidsconf -A -s /sbin/init -o CAP_KILL -j GRANT
Now, we allow fstab and init scripts to mount filesystems, kill processes and unmount filesystems:
lidsconf -A -s/etc/fstab -o CAP_SYS_ADMIN -j 1 -j GRANT lidsconf -A -s /etc/rc.d/init.d/halt -o CAP_INIT_KILL -i 1 -j GRANT lidsconf -A -s /etc/rc.d/init.d/halt -o CAP_KILL -i 1 -j GRANT lidsconf -A -s /etc/rc.d/init.d/halt -o CAP_NET_ADMIN -i 1 -j GRANT lidsconf -A -s /etc/rc.d/init.d/halt -o CAP_SYS_ADMIN -i 1 -j GRANT
Apache needs to have setuid and setgid capabilities. We also need to allow Apache to access log files and deny other applications from accessing the httpd binary:
lidsconf -A -s /usr/local/apache/bin/httpd -o CAP_SETUID -j GRANT lidsconf -A -s /usr/local/apache/bin/httpd -o CAP_SETGID -j GRANT lidsconf -A -o /etc/httpd -j DENY lidsconf -A -s /usr/local/apache/bin/httpd -o /etc/httpd -j READONLY lidsconf -A -o /usr/local/apache -j DENY lidsconf -A -s /usr/local/apache/bin/httpd -o /usr/local/apache -j READONLY lidsconf -A -o /var/log/httpd -j DENY lidsconf -A -s /usr/local/apache/bin/httpd -o /var/log/httpd -j APPEND lidsconf -A -s /usr/local/apache/bin/httpd -o /usr/local/apache/logs -j WRITE
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide