1. The Open Source Solutions Center
Red Hat Enterprise Linux
Installation, Trouble Shooting and
Security Services
Prepared By: KIM Heanh

2. About: KIM Heanh
• 6 years experiences on Network Professional Trainer
• Completed Training Skill from India

3. Objectives
• RED HAT Enterprise Linux
• The Fedora Project
• RED HAT Installation Method
• Fault Analysis
• Fix problems in different areas of the Linux system
• Boot the system into various runlevels
• Use the Rescue environment
• TCP_wrappers
• SELinux Management
• Iptables rules considerations

4. RED HAT Enterprise Linux
• Enterprise-targeted operating system
• Focused on mature open source technology
• 18-24 month release cycle

5. The Fedora Project
• Red Hat sponsored open source project
• Focused on latest open source technology
– Rapid four to six month release cycle
– Available as free download from the Internet
• An open, community-supported proving
ground for technologies which may be used in
upcoming enterprise products
• Red Hat does not provide formal support

6. RED HAT Installation Method
• Available Installation Methods:
– Local CDROM
– USB
– Hard drive
– NFS image
– FTP
– HTTP
– PXE
– vmlinuz
– vnc
• Kickstart
– Scripted Installation method
– Supports all Anaconda features

7. Fault Analysis
• Useful commands
– grub-install
– mkinitrd
– chroot
– rpm -ivh --force
– service <service process> configtest
• Useful file locations
– /etc/inittab
– /etc/fstab
– /etc/grub.conf

8. Fix problems in different areas of the Linux system
• Based on console running
Ctrl + Alt (F1-F6)
• ssh remote

9. Recovery Run-Levels
• The default runlevel file /etc/inittab
• Runleve 1, s, S or single

10. Rescue Environment
• Required when root filesystem is unavailable
• Boot from CDROM (boot.iso or CD #1)
• Boot from diskboot.img on USB key

11. tcp_wrappers
• Three stages of access checking
Is access explicitly permitted?
Otherwise, is access explicitly denied?
Otherwise, by default, permit access!
• Configuration stored in two files:
Permissions in /etc/hosts.allow
Denials in /etc/hosts.deny

12. SELinux: Management
• Modes: Enforcing, Permissive, Disabled
Changing enforcement is allowed in the
Targeted policy
getenforce
setenforce 0 | 1
Disable from GRUB with selinux=0

13. iptables rules considerations
• Mostly closed is appropriate
iptables -P INPUT DROP
iptables -A INPUT -j DROP
iptables -A INPUT -j REJECT
• Criteria also apply to loopback interface
The example rules above will have the side
effect of blocking localhost!

14. Question?