The idea was :

use two servers; server1, and server2
create user: user1 in both server1 and server2
use nmtui to assign IP Addresses to both
use ifdown and ifup to check if IPs are assigned properly
change /etc/hosts and add the server ips and names
use ping to know that you can reach each other
use ssh-key gen to create key files
use ssh-copy-id to transfer public key file to remote hosts
then use ssh commands to reach to without passwords
try scp and sftp : to copy files/folder to and from

Then use TCP wrappers to allow or deny remote hosts, users, or domains

SSH:

2 useradd user1
3 passwd user1
4 ip addr
5 nmtui
6 vim /etc/hosts
7 ping server2
8 ip addr
9 nmtui
10 ifdown ens33
11 ifup ens33
12 ping 192.168.1.200
13 vim /etc/hosts
14 ping server2
15 su user1

ssh-keygen
1 ssh server2 /bin/ls -l
2 scp file1 server2:
3 touch file1
4 scp file1 server2:
5 scp server2:/usr/bin/zip .

7 sftp server2
8 su root

10 w
11 last

13 tail /var/log/secure

15 sudo tail /var/log/secure

19 getcwd

24 ssh-keygen

27 ssh-copy-id -i ~/.ssh/id_rsa.pub server2

31 vim .ssh/authorized_keys
32 ssh server2

———————

TCP wrappers
/etc/hosts.allow : to allow to services from whom
/etc/hosts.allow : to deny to services from whom

Install TCP Wrappers. I used rpm as I turned off internet in the VMware workstation I used

27 rpm -ivh tcp_wrappers*
28 yum info tcp_wrappers
29 ls /etc/hosts.allow
30 vim /etc/hosts.allow
30 vim /etc/hosts.allow

example rules on hosts.allow

All:All
All:user1
All:user1@server2
All:.justetc.com
sshd:LOCAL
vsftpd:192.168.1.200
All Except sshd:192.168.1.200 From: http://sitestree.com/?p=11978
Categories:DevOps
Tags:
Post Data:2017-12-15 12:37:07

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RHCE: MariaDB Administration on Redhat/Fedora/CentOS

Check if mariaDB is installed or not

130 yum list installed | grep ^mariadb

mariaDB originated from MySQL – after MySQL Got Bought by Oracle

133 yum list installed | grep ^mariadb

I see – installed though not completely

Output:

mariadb-libs.x86_64 1:5.5.52-1.el7 @anaconda

There are two other components: mariaDB – client component. MariaDB-server: Server Component

The MariaDB packages:
138 mariadb-bench.x86_64 mariadb-devel.x86_64 mariadb-server.x86_64 mariadb-test.x86_64 mariadb.x86_64

Install all packages at once

139 yum install mariadb*
140 yum list installed | grep ^mariadb

Now, I see the following, after I have installed – all MariaDB packages available in my system
mariadb.x86_64 1:5.5.52-1.el7 @local
mariadb-bench.x86_64 1:5.5.52-1.el7 @local
mariadb-devel.x86_64 1:5.5.52-1.el7 @local
mariadb-libs.x86_64 1:5.5.52-1.el7 @anaconda
mariadb-server.x86_64 1:5.5.52-1.el7 @local
mariadb-test.x86_64 1:5.5.52-1.el7 @local

MariaDB Configuration Files
149 ls /etc/my.cnf
150 ls /etc/my.cnf.d/*

The files
/etc/my.cnf.d/client.cnf /etc/my.cnf.d/mysql-clients.cnf /etc/my.cnf.d/server.cnf

153 vim /etc/my.cnf
154 vim /etc/my.cnf.d/client.cnf
155 vim /etc/my.cnf.d/server.cnf
156 vim /etc/my.cnf.d/mysql-clients.cnf
157 main config file /etc/my.cnf

158 grep -v ^# /etc/my.cnf : will show lines that are not comments
159 grep -v ^# /etc/my.cnf

The content of my.cnf : some lines are self explanatory

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

MariaDB messages are logged at: /var/log/mariadb/mariadb.log

MySQL Specific Selinux Contexts
171 ps -eZ | grep mysqld
I do not see anything as mysqld/maridb is not running

178 systemctl start mariadb.service
179 systemctl enable mariadb.service
180 ps -eZ | grep mysqld

now the output:
system_u:system_r:mysqld_safe_t:s0 4428 ? 00:00:00 mysqld_safe
system_u:system_r:mysqld_t:s0 4585 ? 00:00:00 mysqld

184 mysqld runs on it’s own domain mysqld_t

Related Selinux file type: mysql_exec_t
etc_t is for /etc/my.cnf.d
mysql_db_t is for /var/lib/mysql/
mysql_log_t is for /var/log/mariadb/
189 ll -dZ /usr/libexec/mysqld /etc/my.cnf.d /var/lib/mysql /var/log/mariadb

The output – please note the Selinux Contexts in the output
drwxr-xr-x. root root system_u:object_r:mysqld_etc_t:s0 /etc/my.cnf.d
-rwxr-xr-x. root root system_u:object_r:mysqld_exec_t:s0 /usr/libexec/mysqld
drwxr-xr-x. mysql mysql system_u:object_r:mysqld_db_t:s0 /var/lib/mysql
drwxr-x—. mysql mysql system_u:object_r:mysqld_log_t:s0 /var/log/mariadb

Corresponding Selinux Port Type: mysql_port_t
196 semanage port -l | grep mysqld
output:
mysqld_port_t tcp 1186, 3306, 63132-63164

Related Selinux Booleans: mysql_connect_any, selinuxuser_mysql_connect_enabled
200 getsebool -a | grep mysql

I see the output
mysql_connect_any –> off
selinuxuser_mysql_connect_enabled –> off

To install MariaDB-Server:
205 yum -y install mariadb-server
already installed. we installed with yum -y install mariadb* [installed everything together]

207 systemctl enable mariadb

We can run mysql_secure_installation – to secure our MariaDB installation
209 mysql_secure_installation

—–

The Output: from mysql_secure_installation command
NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!
In order to log into MariaDB to secure it, we’ll need the current
password for the root user. If you’ve just installed MariaDB, and
you haven’t set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none):
OK, successfully used password, moving on…

Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.

Set root password? [Y/n] y
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
… Success!

By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them. This is intended only for testing, and to make the installation
go a bit smoother. You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] y
… Success!

Normally, root should only be allowed to connect from ‘localhost’. This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] y
… Success!

By default, MariaDB comes with a database named ‘test’ that anyone can
access. This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] y
– Dropping test database…
… Success!
– Removing privileges on test database…
… Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] y
… Success!

Cleaning up…

All done! If you’ve completed all of the above steps, your MariaDB

installation should now be secure.
Thanks for using MariaDB!

Enable MariaDB through Firewall and Allow traffic on Port 3306 – default mysql port
218 firewall-cmd –add-service=mysql –perm
220 firewall-cmd –reload

221 systemctl start mariadb
222 systemctl status mariadb
223 start mysql/mariadb

Run MySQL

224 mysql -u root -p

mysqldump is used to backup a database
mysql command can be used to restore a database
you can even use IDEs such as MySQL Workbench to backup and restore MySQL Databases

228 mysql -u root -p
229 mysqldump -u root -p testsayed > testsayeddb.sql

to restore – you need to use < testsayeddb.sql
231 mysql -u root -p testsayed < testsayeddb.sql

Backup and Restore MySQL Database

You can backup multiple databases at once, you can even backup some tables or other database objects using mysqldump

similarly, you can restore multiple databases at the same time using mysql command
just use multiple datbase or database object names with NO comma – one after another

235 mysqldump -u root -p DB1 DB2 DB3 > alldb.sql

when you use restore and give the sql file – if you use db name or table name before < then only that part will be restored irrespective hiow much data is there on the file

example
238 mysql -u root -p DB1 tbl1 < alldb.sql ;

you can use –all-databases or –databases with mysqldump command From: http://sitestree.com/?p=12128
Categories:DevOps, RHCE
Tags:
Post Data:2018-01-03 18:59:06

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AutoFS and Mounting in Linux/Redhat/CentOS

echo “AutoFS – Automatic FS system Mounting – Dec 26th, 2017 by Sayed”

check if Autofs installed or not
yum list installed | grep autofs

I just installed; hence it is there
you can install with yum -y install autofs

944 yum -y install autofs

then you can enable autofs
946 systemctl status autofs
947 systemctl start autofs
948 systemctl enable autofs

enable – will start this service at reboot/system start

AutoFS in general does not use /etc/fstab
AutoFS uses /etc/mtab file
Also, AutoFS has some files under /etc and starting with auto. You can also define which file will contain the mounting mapping. the file that will act like /etc/fstab for autofs

AutoFS has direct mapping and indirect mapping
let’s see some files under /etc for autofs

955 ls /etc/auto*

The files

/etc/auto.direct /etc/autofs.conf /etc/autofs_ldap_auth.conf /etc/auto.master /etc/auto.misc /etc/auto.net /etc/auto.smb /etc/auto.master.d:

I saw to use /etc/auto.master for configuring which file will do the mapping for direct mounting.
I saw to use /etc/auto.misc for configuring which file will do the mapping for indirect mounting for AutoFS.

One more config file is under: /etc/sysconfig/autofs

961 cat /etc/sysconfig/autofs

the content
#
# Init system options
#
# If the kernel supports using the autofs miscellanous device
# and you wish to use it you must set this configuration option
# to “yes” otherwise it will not be used.
#
USE_MISC_DEVICE=”yes”
#
# Use OPTIONS to add automount(8) command line options that
# will be used when the daemon is started.
#
#OPTIONS=””
#

For mounting NFS i.e. remote/network file-systems/folders – we can use the regular mounting i.e. /etc/fstab and mount command. However, that is kinda manual. We can mount NFS using AutoFS that will be automatic mount

We use AutoFS for LDAP clients to auto mount Users’ home directories. We just configure, then the mounting happens automatically. You remember that getent passwd user-name mounted the remote users’ home directory into local system. we used /etc/auto.master to tell that auto.guests will have the mounting configurations. then on /etc/auto.guests file – we configured that users’ home directories will be mounted on /home/guests. you can check our notes on LDAP client configuration

979 cat /etc/auto.master
980 vim /etc/auto.master

we added the following line on /etc/auto.master
/etc/auto.guests /etc/auto.direct

it just tells that AutoFS will consult /etc/auto.guests file for direct mapping

984 vim /etc/auto.guests
we added the following line on /etc/auto.guests
/home/guests 192.168.1.15:/nfsrh

it just tells remote /nfsrh will be automatically mounted to /home/guests
you can try to restart autofs

989 systemctl restart autofs

Indirect Map
indirectly mounted points are only visible when accessed
automatically mounts shares under one common parent directory
each indirect map put only one entry in the mtab file
local and indirect maps cannot exist in the same parent directory
for indirect mapping – you use /etc/auto.misc file From: http://sitestree.com/?p=12070
Categories:DevOps, RHCSA
Tags:
Post Data:2017-12-26 15:27:27

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598 echo “dec 24th, 2017”
599 echo “NTP Client”
600 yum list ntp
601 yum list installed |grep ntp

602 To activate ntp
603 yum -y install ntp system-config-date
604 cat /etc/ntp.conf
605 grep ^server /etc/ntp.conf

606 systemctl restart ntpd
607 systemctl enable ntpd
608 systemctl start ntpd

609 ntpq -p

612 nmtui
613 ip addr

619 system-config-date
620 system-config-authentication

  From: http://sitestree.com/?p=12062
Categories:DevOps, RHCSA
Tags:
Post Data:2017-12-24 22:27:52

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echo “Dec 24th, 2017”
532 echo “Basic Networking in Linux”
533 hostname
534 uname -a
535 uname -n
536 cat /etc/hostname
537 nmcli general hostname
538 changing hostname temporarily
539 hostname server10.example.com
540 for permanent change
541 hostnamectl set-hostname server100.example.com
542 or change /etc/hostname file
543 vim /etc/hostname
544 restart systemctl
545 systemctl restart systemd-hostnamed
546 systemctl restart systemd-hostnamed.service
547 echo “IPV4 addresses”
548 ip addr
549 cat /etc/protocols
550 ip neighbor
551 yum install arp*
552 cat /etc/services
553 cat /etc/protocols
554 ip neighbor
555 interface configuration files
556 cat /etc/sysconfig/network-scripts/
557 ll /etc/sysconfig/network-scripts/
558 ll /etc/sysconfig/network-scripts/ifcfg-*
559 you can change parameters for the interface config files
560 ll /etc/sysconfig/network-scripts/ifcfg-ens33
561 cat /etc/sysconfig/network-scripts/ifcfg-ens33
562 name and IP conversion. /etc/hosts – DNS is the system to do this.
563 interface stop and start
564 ifdown ens33; ifup ens33
565 cat /etc/default/grub
566 it used to be eth0 eth1, now default is ens
567 you can change that using some config changes
568 ip
569 nm-connection-editor
570 nm-connection-editor is graphical nmtui is text based – not command line but text based interface
571 nmtui is command line based. nmtui is text-based interface based
572 nmcli
573 nmcli device show
574 nm-connection-editor
586 to set ipv4 address – one example

589 ip addr add 192.168.0.111/24 broadcast 192.168.0.255 dev ens33
590 ip addr
591 ip addr add 192.168.0.111/24 broadcast 192.168.0.255 dev eth1
592 ls
593 systemctl status NetworkManager
594 nmcli con show
595 nmcli dev status
596 exit
597 history From: http://sitestree.com/?p=12059
Categories:DevOps, RHCSA
Tags:
Post Data:2017-12-24 22:13:22

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