Category: Linux

  • lsblk

    lsblk list all block level devices available on your system.

    Example

    root@ok:~# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0  100G  0 disk 
├─sda1   8:1    0   98G  0 part /
├─sda2   8:2    0    1K  0 part 
└─sda5   8:5    0    2G  0 part [SWAP]
sdb      8:16   0  700G  0 disk 
└─sdb1   8:17   0  700G  0 part /backup
sr0     11:0    1  655M  0 rom  
loop0    7:0    0 36.4M  1 loop /snap/heroku/1513
loop1    7:1    0 83.8M  1 loop /snap/core/3748
loop2    7:2    0   16M  1 loop /snap/heroku/1527
root@ok:~#

    See fs

  • Add Server to R1Soft Server Backup Manager

    After installing r1soft backup agent, you need to add the server to R1Soft Server Backup Manager SE.

    Click on “Protected Machines” link on left side menu.

    Click on “New Machine” button.

    r1soft backup

    On this page, enter following details “Machine Name” and “Hostname / IP”. I used host name as Machine Name. Then used IP address. I don’t enable Encryption, you can enable it for added security.

    Click Save button.

    Now login to server where Backup Agent is installed (Protected Machine) and run

    serverbackup-setup --get-key http://url-of-backup-manager-server

    Example

    [root@server1 ~]# serverbackup-setup --get-key https://22536.r1softlicenses.com
Key '22536.r1softlicenses.com' successfully installed
[root@server1 ~]#

    Now verify key is added with command

    [root@server1 ~]# serverbackup-setup --list-keys
Installed keys:
    22536.r1softlicenses.com
1 keys installed

[root@server1 ~]#

    Next, you need to Configure Server Backup in R1Soft Backup Manager

  • Install R1Soft Agent

    To install R1Soft Agent on CentOS, create a file

    vi /etc/yum.repos.d/r1soft.repo

    Add

    [r1soft]
name=R1Soft Repository Server
baseurl=http://repo.r1soft.com/yum/stable/$basearch/
enabled=1
gpgcheck=0

    Now you can install Agent with command

    yum install serverbackup-enterprise-agent -y

    Install module with command

    r1soft-setup --get-module

    Restart cdp-agent

    /etc/init.d/cdp-agent restart

    You can stop/start agent with command

    service cdp-agent stop
service cdp-agent start
service cdp-agent status

    Once installed, verify connectivity with command

    serverbackup-setup --test-connection

    See r1soft

  • Delta RPMs disabled

    When i install software on CentOS server, i get following warning

    Delta RPMs disabled because /usr/bin/applydeltarpm not installed.

    You can install deltaparm package

    yum install deltarpm -y

    This will save you some bandwidth as yum will only download difference between previous package.

  • r1soft

    r1soft is a backup software from https://www.r1soft.com

    Installing Agent

    r1Soft Setup

    Using r1Soft Server Backup

    r1Soft Errors

    See Backup

  • fs

    btrfs

    lsblk

    xfs

  • btrfs

    On Ubuntu, install it with

    apt install btrfs-tools

    To format a partition in btrfs, run

    root@backup:~# mkfs.btrfs -L mydisk /dev/sdc
btrfs-progs v4.4
See http://btrfs.wiki.kernel.org for more information.

Performing full device TRIM (32.00GiB) ...
Label:              mydisk
UUID:               14049348-3ebd-4e4e-b932-f4a041e72e46
Node size:          16384
Sector size:        4096
Filesystem size:    32.00GiB
Block group profiles:
  Data:             single            8.00MiB
  Metadata:         DUP               1.01GiB
  System:           DUP              12.00MiB
SSD detected:       no
Incompat features:  extref, skinny-metadata
Number of devices:  1
Devices:
   ID        SIZE  PATH
    1    32.00GiB  /dev/sdc

root@backup:~# parted /dev/sdc print
Model: ATA QEMU HARDDISK (scsi)
Disk /dev/sdc: 34.4GB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags: 

Number  Start  End     Size    File system  Flags
 1      0.00B  34.4GB  34.4GB  btrfs

root@backup:~#

    To mount, use

    mkdir /mydisk
mount /dev/sdc /mydisk

    Since we don’t create any partition inside /dev/sdc, we just use sdc instead of normal sdc1.

    I tried with /dev/sdc1, but did not work.

    root@backup:~# mount /dev/sdc1 /mydisk
mount: special device /dev/sdc1 does not exist
root@backup:~# mount /dev/sdc /mydisk
root@backup:~#
  • zypper

    zypper

    zypper command is used for package management in OpenSUSE.

    To update your system, run

    zypper update

    Install a Software

    zypper install PACKAGE_NAME

    Example

    zypper install

    Finding Package

    To find package that provide the software need, you can use 

    zypper search PACKAGE_NAME

    Example

    zypper search php

    SUSE | openSUSE

  • yast

    yast is configuration manager for openSUSE linux.

    openSUSE

  • hostnamectl

    To set hostname for your server in CentOS 7, run

    hostnamectl set-hostname YOUR_HOST_NAME

  • CloudLinux

    CloudLinux has 2 types of licenses, IP based and key based.

    You can check the type of license you have at

    https://cln.cloudlinux.com/console/check-license

    If you have IP based, run

    /usr/sbin/clnreg_ks --force

    For key-based, run

    /usr/sbin/rhnreg_ks --activationkey=KEY_HERE --force

    PHP Selector

  • ufw

    The Uncomplicated Firewall (ufw) is a user-friendly interface for managing netfilter, the standard firewall utility included with most Ubuntu and Debian-based Linux distributions. ufw simplifies firewall configuration by providing straightforward commands for enabling, disabling, and managing firewall rules without requiring extensive networking knowledge.

    To enable ufw to start automatically at boot:

    systemctl enable ufw

    To start or stop the firewall:

    ufw enable
ufw disable

    To see the status, run

    ufw status
ufw status numbered

    Open Ports

    Here are some commands to open ports.

    ufw allow ssh
ufw allow http
ufw allow https
ufw allow 3333/tcp

    Following command open tcp ports 8000 to 9000.

    ufw allow 8000:9000/tcp

    Disable all other ports by default for incoming and allow all outbound traffic

    ufw default deny incoming
ufw default allow outgoing

    Block a port, below example will block port 80

    ufw deny 80/tcp

    Whitelist an IP

    To allow an IP to access all services

    ufw allow from IP_ADDR_HERE

    To allow to specific PORT

    ufw allow from IP_ADDR_HERE proto tcp to any port PORT_HERE
ufw allow from IP_ADDR_HERE proto udp to any port PORT_HERE

    Enable Logging

    To enable logging, run

    ufw logging on

    By default ufw logs to /var/log/kern.log.

    To log to different file, edit

    vi /etc/rsyslog.d/20-ufw.conf

    Uncomment the line

    :msg,contains,"[UFW " /var/log/ufw.log

    rstart rsyslog

    systemctl restart rsyslog

    To allow all Cloudflare IP addresses for web traffic, use the following command. This is useful if your server is behind Cloudflare’s CDN:

    for cfip in `curl -sw '\n' https://www.cloudflare.com/ips-v{4,6}`; do ufw allow proto tcp from $cfip comment 'Cloudflare IP'; done

    To list available apps, run

    ufw app list

    See firewall