DEV Community: Muhammad Shahidul Islam

CentOS Stream 9 : Initial Settings : Add User Accounts

Muhammad Shahidul Islam — Thu, 28 Nov 2024 11:53:23 +0000

To add user accounts on CentOS Stream Server, Configure like follows.
[1] For example, Add [centos] user.

[root@localhost ~]# useradd centos
[root@localhost ~]# passwd centos
Changing password for user centos.
New UNIX password:              # input any password you'd like to set
Retype new UNIX password:       # confirm
passwd: all authentication tokens updated successfully.

[2] If you'd like to switch to root account from a user added above, use [su] command to do so.

localhost login: centos         # login username
password:                       # input user password
[centos@localhost ~]$ su -      # switch to root
Password:                       # input root password
[root@localhost ~]#             # just switched to root

[3] If you'd like to limit users to run [su] command, configure like follows.
On the example below, only users in [wheel] group can run [su] command.

[root@localhost ~]# usermod -aG wheel centos
[root@localhost ~]# vi /etc/pam.d/su
#%PAM-1.0
auth            sufficient      pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth           sufficient      pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
# uncomment the following line
auth            required        pam_wheel.so use_uid
auth            substack        system-auth
auth            include         postlogin
account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet
account         include         system-auth
password        include         system-auth
session         include         system-auth
session         include         postlogin
session         optional        pam_xauth.so

# verify settings with a user who is not in allowed group
[redhat@localhost ~]$ su -
Password:
su: Permission denied     # denied normally

[4] If you'd like to remove a user accounts, Set like follows.

# remove a user [centos] (only removed user account)
[root@localhost ~]# userdel centos
# remove a user [centos] (removed user account and his home directory both)
[root@localhost ~]# userdel -r centos

CentOS Stream 9 : Install Samba to Configure File Server.

Muhammad Shahidul Islam — Thu, 28 Nov 2024 11:48:05 +0000

For example, Create a fully accessed shared Folder which anybody can read and write, and also authentication is not required.
[1] Install and Configure Samba.

[root@smb ~]# dnf -y install samba
[root@smb ~]# mkdir /home/share
[root@smb ~]# chmod 777 /home/share
[root@smb ~]# vi /etc/samba/smb.conf
[global]
        # line 11 : add (set charset)
        unix charset = UTF-8
        workgroup = SAMBA
        security = user
        # add IP addresses you allow to access
        hosts allow = 127. 10.0.0. 
        # add (no authentication)
        map to guest = Bad User

.....
.....

# add to the end
# any Share name you like
[Share]
        # specify shared directory
        path = /home/share
        # allow writing
        writable = yes
        # allow guest user (nobody)
        guest ok = yes
        # looks all as guest user
        guest only = yes
        # set permission [777] when file created
        force create mode = 777
        # set permission [777] when folder created
        force directory mode = 777 

[root@smb ~]# systemctl enable --now smb

[2] If SELinux is enabled and also use [/home] like this example, Change SELinux policy.


[root@smb ~]# setsebool -P samba_enable_home_dirs on
[root@smb ~]# restorecon -R /home/share

[3] If Firewalld is running, allow Samba service.

[root@smb ~]# firewall-cmd --add-service=samba
success
[root@smb ~]# firewall-cmd --runtime-to-permanent
success

CentOS Stream 9 : Memcached : PHP

Muhammad Shahidul Islam — Wed, 27 Nov 2024 08:01:48 +0000

This is the example to use Memcached on PHP.

# install from EPEL, CRB
[root@localhost ~]# dnf --enablerepo=epel,crb -y install php-pecl-memcached

This is the Basic usage on PHP.

[cent@dlp ~]$ vi use_memcache.php
<?php
$memcache = new Memcached();
$memcache->addServer('localhost', 11211);
$memcache->setOption(Memcached::OPT_COMPRESSION, false);

// set and get a Key
$memcache->set('key01', 'value01');
print 'key01.value : ' . $memcache->get('key01') . "\n";

// append and get a Key
$memcache->append('key01', ',value02');
print 'key01.value : ' . $memcache->get('key01') . "\n";

$memcache->set('key02', 1);
print 'key02.value : ' . $memcache->get('key02') . "\n";

// increment
$memcache->increment('key02', 100);
print 'key02.value : ' . $memcache->get('key02') . "\n";

// decrement
$memcache->decrement('key02', 51);
print 'key02.value : ' . $memcache->get('key02') . "\n";

?>

# run
[cent@localhost ~]$ php use_memcache.php
key01.value : value01
key01.value : value01,value02
key02.value : 1
key02.value : 101
key02.value : 50

CentOS Stream 9 : Memcached : Install

Muhammad Shahidul Islam — Wed, 27 Nov 2024 07:53:53 +0000

Install Memcached, which is the distributed memory caching system.

Install Memcached.

# install from EPEL, CRB
[root@localhost ~]# dnf --enablerepo=epel,crb -y install php-pecl-memcached

It's possible to change settings of Memcached on [/etc/sysconfig/memcached].
For other options, you can see [man memcached].

[root@localhost ~]# vi /etc/sysconfig/memcached
# listening port
PORT="11211"
# process owner
USER="memcached"
# max connections
MAXCONN="1024"
# max cache memory size (MB)
CACHESIZE="64"
# possible to specify options here
# listen on localhost by default like follows
# if you'd like to use memcached from other Hosts, change to own IP address or to [0.0.0.0]
OPTIONS="-l 127.0.0.1,::1"
[root@dlp ~]# systemctl enable --now memcached

If you'd like to use Memcached from other Hosts and also Firewalld is running, allow service.

[root@dlp ~]# firewall-cmd --add-service=memcache
success
[root@dlp ~]# firewall-cmd --runtime-to-permanent
success