With a world that is vastly growing in size so does our use for technology. With this use of technology come lots of potential threats and hazards. Our world today is ever so growing with its relationship with the internet or World Wide Web (WWW). Many places use the internet to access sites, software, music, book, and so forth, the list goes on. But with this advance in technology come lots of threats to consumers alike. Such as hackers, viruses, people who don’t know what they are doing, and even people who you may call your best friend. Threat comes in many shapes and sizes which is why operating systems such as Linux develop ways to keep your personal files safe from these unwarranted threats. Some of these measures include, but is not limited to; iptables, SELinux, chroot jail, TCP Wrappers, firewalls, PolicyKit, NX or No eXecute, PIE or Position Independent Executables, Netfilter, and the list goes on (“Fedora Projects” & Vepstas).
When a user first approaches Linux it looks similar to what a windows operating system would resemble. With Linux a user has the ability to access every file within the operating system through the use of a terminal or command prompt. Through the use of Linux programming potential threats can gain access to you file system and everything housed within it. Linux is free software that comes with many great security features that any user or administrator greater access and control over the system. The choice can be a bit much for most, but we will discuss a few of these choices here.
Security-Enhanced Linux also known as SELinux is a security program that was developed in partner by the National Security Agency or NSA and Red Hat Developers (“Fedora Project”). So what exactly is it that SELinux does? SELinux was designed so that the Administrator could enforce policies that will limit what a user or particular program would be able to access. SELinux is also a MAC or Mandatory Access Control based security that is enabled by default. Some of the policies used by SELinux was designed to keep out unwanted processes and to protect its users by pretty much being a watch dog. If someone were to attack your system the SELinux limits what damage could actually be done by preventing a file from being read or tampered with.
SELinux will assign a string that states the role, user name, and domain type. If you are not configured by this policy to access certain files you will be denied access. It will let the Admin know what security threats have been made, such a Joe Bob trying to hack into your system to get some personal laughs. SELinux runs on three different states (modes): enforcing-which is the default state of SELinux and is set so that no user or program can do anything without the proper clearance, permissive-which is a diagnostic state that sends warnings, but nothing is enforced and makes a good guide for building a new security policy, and disabled-which basically means its shut off no policy is enforced or loaded., which you can read more about on page 414, Chapter 11 of “A Practical Guide to Fedora and Red Hat Enterprise Linux” cited in the works cited of this document. Another Linux based security program that can be obtained and used is iptables. Linux uses iptables to build and manipulate the network packet filtering rules within the kernel (Sobell, Pg.819). Iptables allow an administrator to setup NAT or Network Address Translation (found on page 1095 of Sobell’s book cited in the works cited page if you want to read more about this), which allow multiple hosts to share a single internet connection and it also filters IP packets, by allowing the admin to accept or deny certain communications ports. Iptables also allow for the creation of firewalls, which is a good source of protection from malicious users and or software. Iptables is a utility that comes with Linux so the user does not need to install it to their system. Iptables is also composed with Netfilter which provide hook handling within the Linux kernel for dealing with network packets.
Another good security program to run on your Linux system is chroot jail (changes the root). This allows for changing of the file system root that a process can see. This limits the process to a subdirectory of the actual system so that if it’s hacked the hacker cannot gain access to directories outside of the jail (Vepstas). There are many ways to break this particular type of security, which include but are not limited to root privileges from within the jail itself. A good source to read about breaking out of a chroot jail is “Simon’s: How to break out of a chroot () jail”, which is cited in the work cited page at the end of this paper.
A chroot is a good thing to use in the line of security, because without it a user may just find their way to top level access despite their permissions. According to Steve Friedl’s web site, also located in the work cited page, there a few general principles one must follow: run in the jail as a non-root user, “give up” permissions correctly, explicitly chdir into the jail, keep as little in the jail as you can, limit non-jail use, create permission-setting script, and try to do the chroot within the daemon itself. These are just listing a few things to keep in mind when setting up a chroot within in your Linux system. You don’t want someone reading something that they shouldn’t be seeing in the first place.
As a person reads more about Linux security they will see that there are vast ways to protect you from harmful outside/inside sources. There is no program out there that can’t be broken into, but one can take extra measure to insure of the chance to less likely happen by protecting themselves and familiarizing themselves with the appropriate security software. Study how to use it, how it works in and out, and even go as far as to learn how it could be broken into. Such attacks like man-in-the=middle attacks, viruses, malware, worms can happen on a regular basis and no one is obsolete from this. If you want to be safe and protect yourself and your company its good practices to know what you’re using.