Ensurepass 9. Other System Administration 9.1 Date/Time 1. redhat-config-time o a.k.a redhat-config-date, dateconfig o GUI based. o Set system time/date. o Select timezone. o Enable Network Time Protocol (NTP). o Set whether hardware clock is set to UTC. 2. timeconfig o TUI based. o Select timezone. o Set whether hardware clock is set to UTC. 3. date o CLI based. o Set system date/time. 4. hwclock o Used to query/set hardware clock. o Can sync the hardware clock to the system clock Read more [...]
Ensurepass 8. Network Administration 8.1 Utilities 1. ifconfig ifconfig is used to configure network interfaces. Example: ifconfig eth0 192.168.1.10 netmask 255.255.255.0 up This configures interface eth0 with an IP of 192.168.1.10/255.255.255.0. Note that "up" is assumed if left off. A default network mask will also be determined by the IP if it is not specified. 2. route route is used configure routing information. Example: route add -net 10.20.30.40 netmask 255.255.255.248 eth0 route Read more [...]
Ensurepass 7. User & Group Administration 7.1 Adding Users 1. useradd o Command line interface o If not specified, defaults in /etc/defaults/useradd and /etc/login.defs are used. o Defaults: 1. userid - lowest unused value >= UID_MIN in /etc/login.defs. 2. home directory - /home/. 3. primary group - a group with the same name as the username. 4. shell - /bin/bash. o Options: o -u - userid o -g - primary group o -s - shell o -d - home directory o -c - comment (Commonly used to specify full Read more [...]
Ensurepass 6. Service Management 6.1 Types of services 1. System V services o Managed by System V init scripts o Scripts are stored in /etc/init.d 2. xinetd services o Services started by the xinetd daemon. o xinetd service control files located in /etc/xinetd.d o Defaults for xinetd set in /etc/xinetd.conf o xinetd itself is a System V service. 3. init services o Configured in /etc/inittab. o Provides respawn capability if service dies. 6.2 Management tools 1. System V services o Read more [...]
Ensurepass 5. Boot up 5.1 Steps 1. BIOS loads first stage boot loader from the first sector of available disks (floppy, hard drive, cd-rom, etc.) 2. First stage boot loader then loads the second stage boot loader. 3. Second stage boot loader allows user to choose what kernel to boot. 4. Chosen kernel then booted and devices are initialized. 5. Kernel then executes init process. 6. Init starts services according to /etc/inittab: o rc.sysinit - System initialization scripts 1. Mounts /proc. Read more [...]
Ensurepass 41. Copyright & Disclaimer 41.1 General Disclaimer First off, I am not currently a RHCE (as of date on this study guide at the top), although I'm planning to get my certification later this year. I created this guide to help myself study for the exam. While the information in this document is correct to the best of my knowledge, I DO NOT guarantee the accuracy of ANY of the information contained in this document. This information comes without any warranty of any kind, implied or otherwise. Read more [...]
Ensurepass 40.1 ?/.fetchmailrc 1. Create a .fetchmailrc file in your home directory similar to the following: 2. poll pop3.somedomain.com with protocol pop3: 3. user steve there is user gandalf here 4. password "super_secret" The first line says that pop3.somedomain.com hosts our pop3 account and that we will contact it using the pop3 protocol. The second line states that the user account on the pop3 server is steve and our local account is gandalf. The last line contains our password for the Read more [...]
Ensurepass 4. Boot Loaders 4.1 Concepts 1. Invocation Invocation of the boot loader usually occurs in one of two ways: o BIOS loads the first stage boot loader from the drive's MBR. o BIOS loads another boot loader which then loads the first stage boot loader from a partition's boot sector. The first stage boot loader is also known as Initial Program Loader (IPL). It must be less than 512 bytes in size, so it is fairly limited. It's primary job is to load a more functional boot loader (a.k.a. Read more [...]
Ensurepass 39. stunnel 39.1 Overview 1. Provides encryption services for applications without modifying the application. 2. Uses public key encryption. 3. Packages stunnel 39.2 Configuration 1. Create stunnel.pem 2. # Generate private key and certificate 3. 4. openssl req -new -newkey rsa:1024 -nodes -x509 -keyout /tmp/key -out /tmp/cert 5. 6. # Create stunnel.pem 7. 8. echo >> /tmp/key 9. cat /tmp/cert >> /tmp/key 10. echo >> /tmp/key 11. rm /tmp/cert 12. mv /tmp/key /usr/share/ssl/certs/stunnel.pem 13. Read more [...]
Ensurepass 38. Encryption (GPG & OpenSSL) 38.1 Overview 1. Why use it? o Prevent password and data sniffing. o Maintain integrity of data. o Prevents authentication manipulation. 2. Packages o OpenSSL - Provides crypto-graphic libraries used by other programs which communicate via the network. o gnupg - Used to insure integrity and encrypt files (e.g. data, e-mail, etc.) o OpenSSH - A secure replacement for ftp, telnet, rsh, rlogin, etc. Covered elsewhere. o stunnel - Provides network encryption Read more [...]
Ensurepass 37. IMAP & POP 37.1 Overview 1. Package o imap 1. The imap package includes the POP daemon also. 2. Provides POP2, POP3, and POP3s (POP3 over SSL) service. 3. Provides IMAP and IMAPs (IMAP over SSL) service. 2. Ports o POP2 - TCP 109 o POP3 - TCP 110 o POP3S (over SSL) - TCP 995 o IMAP - TCP 143 o IMAPS (over SSL) - TCP 993 37.2 Setup 1. Executed by xinetd. 2. Simply install the imap package and enable service(s) in xinetd. Download the Ensurepass Latest 2013 RHCE EX300 Read more [...]