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Flashcards in Deploy, configure, and maintain systems Deck (43)
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1

networking dynamically(from DHCP)

#cat /etc/sysconfig/network-cripts/ifcfg-eth1
DEVICE=eth1
HWADDR=[Mac Address]
TYPE=ethernet
UUID=[uuid number(hex)]
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=dhcp

2

Networking statically

-edit file /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE="eth1"
BOOTPROTO="static"
DNS1="10.1.1.1"
GATEWAY="10.1.1.1"
HWADDR=[MAC Address]
IPADDR="10.1.1.3"
NETMASK="255.255.255.0"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="[UUID hex number]"

3

after making changes to eth files

#ifdown eth1
#ifup eth1

or
#service network restart

4

Primary network configuration files

/etc/hosts
/etc/resolv.conf
/etc/sysconfig/network
/etc/sysconfig/network-scripts/ifcfg-

5

Cron VS at

Cron is used to schedule recurring task while at is used to schedule a task to run at a particular time

6

Setting up a cron

#chkconfig --list crond make sure that crond is set to boot
# service crond status check that crond is started
# cat /etc/crontab see rule example of job definition
* * * * *
1st star is for min(0-59)
2nd star is for hours(0-23)
3rd star is for day (1-31)
4th star is for month(1-12)
5th star is for day of the week(Sunday = 0 or 7, 0-6 Sunday-Saturday)

Review
#ls /var/spool/cron
#cat /var/spool/cron/root

7

Cron jobs that run periodically

These jobs are stored and run periodically
# /etc/cron.daily
# /etc/cron.weekly
# /etc/cron.hourly
# /etc/cron.monthly

8

List crontab

#crontab -l list crontab as owner
#crontab -l -u user1 list crontab as root for user1

9

edit crontab

#crontab -e edit crontab for current user
# crontab -e -u user1 edit crontab for user1
only root can edit other user's crontab

10

/etc/cron.deny and /etc/cron.allow

add user to /etc/cron.deny or /etc/cron.allow to deny or allow them to be able to create cron jobs

11

Setting up at

#service atd status check that the atd service has started
# chkconfig --list atd make sure it's set to start at boot

12

List of commands for at

#at -f file.sh now+2minutes sets a job to run in 2 mins
# atq jobs that are submitted
# atrm 3 remove a job(enter job number)
#at -f some.sh 12pm tomorrow run at 12PM tomorrow
#ls /var/spool/at where the scrip for scheduled jobs are

13

Kickstart

-After an install a ks file is automatically created and stored in /root/anaconda-ks.cfg
- You can create a ks file by hand or you can use the system kickstart utility located here:
Applications -> System tools -> kickstart (it's not installed by default)
- in the kickstart file, the lines that starts with"@" means a group package to be installed. The lines that starts with "-" means to exclue those packages from being installed.

14

Installing from a KS in an NFS partition

-first boot from the boot cd. Then press the ESC key
-at the boot prompt type(press Enter afterward)
boot: linus ks=nfs:IP:/srv/nfs/ks.cfg

15

Installing from a KS in an FTP or http location

While still booting from an actual install cd, you could add the location of the ks to an ftp or http server, and add such entry in the KS file:
usr --url=http://ip/rhel6
-After booting from the DVD install, press the tab key, then enter:
> vmlinuz initrd = initrd.img ks=http://ip/rhel/ks.cfg ksdevice=eth0

or
> vmlinuz initrd = initrd.img asknetwork ks=http://your.web.com/rhel6.cfg ksdevice=eth0

16

Kernel boot options:

- linux ks = ftp://host/ks.cfg
- linux ks = http://host/ks.cfg
- linux ks = nfs:host:/ks.cfg
- linux ks=hd:/dev/dir/ks.cfg
- linux ks=file:/dev/dir/ks.cfg

17

NTP

You can syncronize the system clock with a remote server over the network Time Protocol(NTP). for the one-time synchronication only use the ntpdate command

18

the ntpdate command

1- first check whether the selected NTP server is accessible
#ntpdate -q server-address
2- run the command followed by one or more server addresses
#ntpdate server_address ....
enable running the ntpdate at boot time
#chkconfig ntpdate on

19

Note if the synchronization with the time server at boot time keeps failing

You can find a relevant error message in the /var/log/boot.log. Then try to add the following line to /etc/sysconfig/network
NETWORKINGWAIT=1

20

Best to set the ntpd daemon

The most convenient way is to set the netpd daemon to synchronize the time at boot time automatically
1. Open the NTP configuration file /etc/ntp.conf
2. add or edit the list of public NTP servers
server 0 rhel.pool.ntp.org iburst
-The iburst directive is to speed up the initial synchronization as of redhat 6.5, it is added by default.
3. In the same file, set the proper permissions giving unrestricted access to localhost only
restrict 127.0.0.1
restrict 6::1
4. save all changes, exit and restart the NTP daemon
#service ntpd restart
5 make sure that ntp is started at boot time
#chkconfig ntpd on

Note, if you are setting up the NTP server for others to access, remember to enable port 123 in the firewall.

21

Yum repos

- yum repos are located in /etc/yum.repos.d
- all repository should end with .repo
- no two repository can have the same repository ID

22

Example of a repo file

[localnet]
name = local network yum repo
baseurl = ftp://192.168.75.132/pub/
enabled=1
gpgcheck=0
gpgkey=file:///etc/......

review man yum.conf

23

To register for red hat subscription

#rhn_register then follow the instructions

24

Setting up a local repo with a disk

- first mount the disk
-copy the packages from Packages into another directory
-next install the package createrepo
- once installed add into the directory and run
# createrepo
-Then create a file in /etc/yum.repos.d/ similar to
# vi mylocal.repo
[mylocal]
name=mylocal
baseurl=file:///directory/path/to/repo
enabled=1
gpgcheck=0

25

To test for a specific package

# yum list httpd

26

Install and update software packages using rpm

#rpm -ivh mypackage.rpm
#rpm -Uvh mypackage.rpm

27

How to import the gpg key of repository

#rpm --import gpgkey

28

to see a list of repos

#yum repolist

29

installing and update via yum

#yum install vsftp
#yum update vsftp

30

Get kernel current version

#uname -r