© 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Security Strategies in Linux Platforms and Applications Lesson 2 Basic Components of Linux Security

Page 2 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Learning Objective  Describe components of Linux security.

Page 3 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Key Concepts  Understand boot loaders  Security considerations while using kernel and user space components  Discretionary access control (DAC) and access control lists (ACLs)  Mandatory access control (MAC) with Security Enhanced Linux (SELinux)  Concepts of a packet filtering firewall

Page 4 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. DISCOVER: CONCEPTS

Page 5 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Common Boot Loaders  Grand Unified Bootloader (GRUB)  Linux Loader (LILO)  Loadlin  Universal Bootloader (U-Boot)

Page 6 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Configuration OptionsComments default=0Is for default kernel to boot timeout=0Sets the timeout to zero color green/blueSpecifies the color for the GRUB screen password – md5 Is for the encrypted password splashimage=(hd0,0)/gru b/splash.xpm.gz Is for “splash” image that shows when you access the GRUB menu GRUB Configuration Options

Page 7 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. The Linux Firewall Location of iptables Location of netfilter User

Page 8 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Layered Security

Page 9 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. DISCOVER: PROCESS

Page 10 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Common Linux Access Controls

Page 11 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. DISCOVER: ROLES

Page 12 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Access Control Mechanisms DAC  Defines the access control for objects in the filesystem ACLs  Grants “special” permissions to users or groups for an object in the filesystem that are not specified in the DAC permissions MAC  Adds additional categories to objects in the filesystem

Page 13 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. DISCOVER: CONTEXTS

Page 14 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Kernel Space  Kernel space has access and can control all aspects of a Linux system  Loadable kernel modules (LKMs) are a common avenue for rootkits

Page 15 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. User Space  User space is the most likely avenue that black-hat hackers attempt to exploit the Linux system.  It is common for black-hat hackers to gain unauthorized access simply by guessing an easy password from a user account.

Page 16 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. DISCOVER: RATIONALE

Page 17 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Importance of a Firewall  Firewall on each host server provides an additional layer of security:  If the network perimeter firewall allows unauthorized traffic into the network, firewall protects servers from the unauthorized traffic.  Firewall provides additional protection to host servers if a rogue program infects the local area network (LAN).

Page 18 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Importance of Securing Core Components  Default settings, improper file permissions, and insecure user accounts are common methods used by black-hat hackers to gain unauthorized access.  Best practices and compliance standards require basic security and can result in hefty fines, if not followed.

Page 19 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Summary  Understand boot loaders  The process of Linux access control  Access control mechanisms such as DAC, ACLs, and MAC  Considerations for using kernel space and user space  Importance of firewall and securing core components

Page 20 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. OPTIONAL SLIDES

Page 21 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. A Linux Kernel Configuration Menu

Page 22 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. Red Hat’s Authentication Configuration Tool

Page 23 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. The Security Level Configuration Tool for Firewalls

Page 24 Security Strategies in Linux Platforms and Applications © 2013 Jones and Bartlett Learning, LLC, an Ascend Learning Company All rights reserved. The SELinux Administration Tool