install and configure x11vnc on ubuntu server 18.04 LTS

sudo apt-get install x11vnc

x11vnc -storepasswd 

Enter VNC password: *********
Verify password: *********  
Write password to /home/rahul/.vnc/passwd?  [y]/n y
Password written to: /home/rahul/.vnc/passwd

sudo x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth /home/rahul/.vnc/passwd -rfbport 5900 -shared

script auto start

1. make file x11vnc.service in /etc/systemd/system :
sudo mcedit /etc/systemd/system/x11vnc.service (mcedit – my prefered editor , i’m sorry for vi :)))

with text (change RAHUL for you name):

[Unit]
Description=x11vnc remote desktop server
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth /home/RAHUL/.vnc/passwd -rfbport 5900 -shared

Restart=on-failure

[Install]
WantedBy=multi-user.target

2. sudo systemctl daemon-reload
sudo systemctl start x11vnc
sudo systemctl status x11vnc

3. if it’s worked
sudo systemctl enable x11vnc.service

Ref: setup-x11vnc-server-on-ubuntu-linuxmint

install and configure snmp

1. For CentOS 7
install service snmp

yum install net-snmp net-snmp-utils -y

Set configure file /etc/snmp/snmpd.conf
--------------------------------edit------------------------------------------------------------
#       sec.name  source          community
com2sec mynetwork  default       systemsecret

####
# Second, map the security name into a group name:

#       groupName      securityModel securityName
group   notConfigGroup v1           mynetwork
group   notConfigGroup v2c          mynetwork

# Make at least  snmpwalk -v 1 localhost -c public system fast again.

#       name           incl/excl     subtree         mask(optional)

view    systemview    included   .1.3.6.1.2.1.1

view    systemview    included   .1.3.6.1.2.1.25.1.1

####

# Finally, grant the group read-only access to the systemview view.

#       group          context sec.model sec.level prefix read   write  notif

access  notConfigGroup ""      any       noauth    exact  systemview none none

--------------------------------save configure-----------------------------------------------

Enable service

systemctl enable snmpd

systemctl start snmpd

systemctl status snmpd

Check port runing

netstat -tulpn

udp        0      0 0.0.0.0:161             0.0.0.0:*                           21402/snmpd

Test snmpd at local server

snmpwalk -v 1 -c systemsecret -O e 127.0.0.1

Add firewall

firewall-cmd --permanent --add-port=161/udp

firewall-cmd --reload

firewall-cmd --list-all

Ref: install-configure-snmp-rhel-7-centos-7

2. For Debain 9
Install service snmpd

apt install snmpd snmp libsnmp-dev

Edit configure /etc/snmp/snmpd.con
---------------------------------------------------------
#  AGENT BEHAVIOUR
#
#  Listen for connections from the local system only
agentAddress  udp:127.0.0.1:161,udp:192.168.0.xx:161

#  ACCESS CONTROL

#

                                                 #  system + hrSystem groups only

view   systemonly  included   .1.3.6.1.2.1.1

view   systemonly  included   .1.3.6.1.2.1.25.1

                                                 #  Full access from the local host

#rocommunity public  localhost

                                                 #  Default access to basic system info

# rocommunity public  default    -V systemonly

 rocommunity serversecret  default    -V systemonly

                                                 #  rocommunity6 is for IPv6

 rocommunity6 public  default   -V systemonly

#rocommunity secret  10.0.0.0/16

                                                 #  Full read-only access for SNMPv3

 rouser   authOnlyUser

#  SYSTEM INFORMATION

#

#  Note that setting these values here, results in the corresponding MIB objects being 'read-only'

#  See snmpd.conf(5) for more details

sysLocation    Sitting on the Dock of the Bay

sysContact     Me

                                                 # Application + End-to-End layers

sysServices    72

---------------------------------------------------------------------------

Enable service

systemctl enable snmpd

systemctl start snmpd

systemctl status snmpd

Check port runing

netstat -tulpn

udp        0      0 192.168.0.xx:161         0.0.0.0:*                           12142/snmpd         

udp        0      0 127.0.0.1:161           0.0.0.0:*                           12142/snmpd

ss -alnp | grep snmp | grep 161

udp    UNCONN     0      0      192.168.0.xx:161                   *:*                   users:(("snmpd",pid=12142,fd=12))

udp    UNCONN     0      0      127.0.0.1:161                   *:*                   users:(("snmpd",pid=12142,fd=9))

Test snmpd at local server

snmpwalk -v2c -c serversecret localhost

Add firewall

firewall-cmd --permanent --add-port=161/udp

firewall-cmd --reload

firewall-cmd --list-all

Ref: how-to-configure-snmp-version-2c-on-debian-9

Configure Master / Slave BIND DNS Server on CentOS 8 / RHEL 8

Configure Master / Slave BIND DNS Server on CentOS 8 / RHEL 8

install-bind-private-dns-server-on-rhel-8

for check zone file

named-checkzone abc.com /var/named/abc.com.zone

Directory zone = /var/named/

dnstop ens192
dnstop -l 2 ens192
dnstop -l 3 ens192
yum install dnstop

How to Add New Disks Using LVM to an Existing Linux System

Read on this web site add-new-disks-using-lvm-to-linux

how to change screen login ubuntu 18.04 budgie

1. create file slick-greeter.conf on /etc/lightdm/

sudo vim /etc/lightdm/slick-greeter.conf
------------------------------------------------------
[Greeter]
#background=/usr/share/backgrounds/Definitive_Light_Zen_Orange_by_Pierre_Cante.jpg
background=/usr/share/backgrounds/cat-login.jpg

-----------------------------------------------------
save file

2. bring your screen login to the folder /usr/share/backgrounds/

3. reboot

Ref:
Greeter

How to check if port is in use on Linux or Unix

sudo lsof -i -P -n | grep LISTEN
sudo netstat -tulpn | grep LISTEN
sudo lsof -i:22 ## see a specific port such as 22 ##
sudo nmap -sTU -O IP-address-Here

Option #1: lsof command
$ sudo lsof -i -P -n
$ sudo lsof -i -P -n | grep LISTEN
$ doas lsof -i -P -n | grep LISTEN ### [OpenBSD] ###

Linux netstat syntax
netstat -tulpn | grep LISTEN
watch netstat -tulpn
sudo ss -tulw
sudo ss -tulwn


netstat -tulpn |grep tcp |grep -v 127.0.0.1 |grep -v 192.168.101.36
-v is invert matching (every thing except 127.0.0.1 and 192.168.101.36)

Where ss command options are as follows:

• -t : Show only TCP sockets on Linux
• -u : Display only UDP sockets on Linux
• -l : Show listening sockets. For example, TCP port 22 is opened by SSHD server.
• -p : List process name that opened sockets
• -n : Don’t resolve service names i.e. don’t use DNS

FreeBSD/MacOS X netstat syntax

$ netstat -anp tcp | grep LISTEN
$ netstat -anp udp | grep LISTEN

OpenBSD netstat syntax

$ netstat -na -f inet | grep LISTEN
$ netstat -nat | grep LISTEN

Option #3: nmap command

The syntax is:
$ sudo nmap -sT -O localhost
$ sudo nmap -sU -O 192.168.2.13 ##[ list open UDP ports ]##
$ sudo nmap -sT -O 192.168.2.13 ##[ list open TCP ports ]##

You can combine TCP/UDP scan in a single command:
$ sudo nmap -sTU -O 192.168.2.13

A note about Windows users

You can check port usage from Windows operating system using following command:
netstat -bano | more
netstat -bano | grep LISTENING
netstat -bano | findstr /R /C:"[LISTEING]"

Ref:
unix-linux-check-if-port-is-in-use-command

How to install and use powershell on ubuntu

snap install powershell –classic

Run Powershell

#powershell

Connect to O365

Create file connect powershell

-------------------connect-exchangeonline.ps1-----------------------------
Set-ExecutionPolicy remotesigned
$UserCredential = (Get-Credential -Credential email@domain.com)
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session -DisableNameChecking

#Remove-PSSession $session


Connect-MsolService -Credential $UserCredential
-------------------End--------------------------------------------------------------

#PS /home/hades/Downloads> ./connect-exchangeonline.ps1
PowerShell credential request
Enter your credentials.

Password for user email@domain.com: *********

Success

Test command
Check version
PS /home/hades/Downloads> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      6.2.1
PSEdition                      Core
GitCommitId                    6.2.1
OS                             Linux 4.15.0-54-generic #58-Ubuntu SMP Mon Jun 24 10:55:24 UTC 2019
Platform                       Unix
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

WSManStackVersion              3.0

MFA 

Connect Exopssession: Connect-EXOPSSession -UserPrincipalName email@yourdomain.com

MFA Function

Connect-MsolService

Close power shell connection:Get-PSSession
Get-PSSession | Remove-PSSession

Create new Distribution group
New-DistributionGroup -Name "Group-test01" -DisplayName "Group test by hades" -Type "Security"

Check distribution group information?
Get-DistributionGroup -Identity "distribution group"

Get-DistributionGroup -Identity "distribution group" | Format-List

Get-DistributionGroup "distribution group" | Format-Table

* Set receive mail from out side

Get-DistributionGroup -Identity Group name | Set-DistributionGroup -RequireSenderAuthenticationEnabled $False

* Show member on group with name and email address
Get-DistributionGroupMember "distribution group" | Format-Table Name, PrimarySMTPAddress -Auto

Check list member email on Distribution group
Get-DistributionGroupMember -Identity "distribution group" | Format-Table Name, Alias, PrimarySMTPAddress -Auto

* Export email form distribute group
Get-DistributionGroupMember -Identity "distribution group" ` | Select-Object Displayname,Name,PrimarySMTPAddress ` | Export-CSV -Path "/home/User/Downloads/distribution group.csv" -Encoding UTF8

* Import email form distribute group
1. create new file .csv like Distibute group.csv and input data like this see below.
-----------------Distibute group.csv---------------
name,emailaddress
jack,jack@domain.com
mack,mack@domain.com
---------------------------------------------
2. run command
Import-Csv group.csv | foreach {Add-DistributionGroupMember -Identity "Distibute group" -Member $_.name}

Add member to distribution group
Add-DistributionGroupMember -Identity "distribution group" -Member "email@domain.com"

Remove distribution group and Member in group

Remove-DistributionGroupMember -Identity "distribution group"
Remove-DistributionGroupMember -Identity "distribution group" -Member "email@domain.com"

View all O365group list
Get-UnifiedGroup -Identity *

View member on O365 group list
Get-UnifiedGroup -Identity groupname | Get-UnifiedGroupLinks -LinkType Member | Format-Table Name, PrimarySMTPAddress

View member on O365 subscribers list ตรวจสอบกรณีคนในกลุ่ม O365 ไม่ได้รับเมล
Get-UnifiedGroupLinks -Identity groupname@domain.com -LinkType subscribers

ให้แอดเพิ่มเข้าไป ด้วยคำสั่งนี้
Add-UnifiedGroupLinks -Identity groupname@domain.com -LinkType subscribers -Links email1@domain.com

Unsubscribers member O365 group
Remove-UnifiedGroupLinks -Identity "groupname" -LinkType Members -Links abc.d@domain.com,abcde.f@domain.com

Export member on O365 group list
Get-UnifiedGroup -Identity groupname | Get-UnifiedGroupLinks -LinkType Member | select Name, PrimarySMTPAddress |Export-Csv C:\Users\user01\Documents\groupname.csv

Add Owner distribution group
-Check owner on distribution
Get-DistributionGroup -Anr "distribution name" | Format-Table Name, ManagedBY, Alias, Email -Auto

-Replace
Set-DistributionGroup "distribution group" -ManagedBy "email@domain.com" -BypassSecurityGroupManagerCheck

-Add more one email
Set-DistributionGroup "distribution group" -ManagedBy 'admin01','admin02','systemadmin' -BypassSecurityGroupManagerCheck

Get mailbox permission
Get-MailboxPermission "user1"

Add Full access mailbox permission : user2 full access user1
Add-MailboxPermission -Identity "user1" -User "user2" -AccessRights FullAccess -InheritanceType All

Remove Full access mailbox permission 
Remove-MailboxPermission -Identity "user1" -User "user2" -AccessRights FullAccess -InheritanceType All

Get Last login:
Get-MailboxStatistics "user1"

Get Mailbox size:
Get-MailboxStatistics "user1" | ft DisplayName, TotalItemSize, ItemCount

Get All Mailbox
Get-Mailbox | Select-Object DisplayName, primarySMTPAddress

Get one mailbox
Get-Mailbox "user1" | Select-Object DisplayName, primarySMTPAddress

Display the list of a SMTP aliases and the primary address 
Get-Mailbox "user1" | fl EmailAddresses, PrimarySmtpAddresses

Add Permission Calendar access mailbox 
Add-MailboxFolderPermission -Identity "user1:\Calendar" -User "user2" -AccessRights Reviewer

Add permission Calendar access Default to Reviewer
Set-MailboxFolderPermission -Identity "user1:\Calendar" -User Default -AccessRights Reviewer

Set permission Calendar access Default (back)
Set-MailboxFolderPermission -Identity "user1:\Calendar" -User Default -AccessRights AvailabilityOnly

View permission calendar who access mailbox
Get-MailboxFolderPermission -Identity "user1:\Calendar"

foreach($i in Get-Mailbox -ResultSize 100 -Filter 'DisplayName -like "*ห้องประชุม*"') {Get-MailboxFolderPermission $($i.Alias + ":\Calendar")| Select-Object Identity,User,AccessRights | Sort-Object Identity}

* -ResultSize Unlimited

Delete user access pemission calendar
Remove-MailboxFolderPermission -Identity "user1:\Calendar" -User "user2"

View number of account license
Get-MsolAccountSku

Get all assigned License office O365
Get-MsolUser -All | Where-Object { ($_.licenses).AccountSkuId -match "nanyangtextilegroup:STANDARDPACK" } | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State,WhenCreated | Export-Csv C:\Users\hades\Documents\allmaillicense2-1.csv

Get-MsolUser -MaxResults 10 | Where-Object { ($_.licenses).AccountSkuId -match "nanyangtextilegroup:STANDARDPACK" } | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State,WhenCreated | Format-Table


Get-MsolUser -All | Where-Object { $_.isLicensed -eq "E1" } | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State,WhenCreated | Export-Csv C:\Users\hades\Documents\allmaillicense2-1.csv

Get all Unlicense office O365
Get-MsolUser -UnlicensedUsersOnly | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State | Export-Csv C:\Users\hades\Documents\unlicense.csv

Get all email user on Department "QA"
Get-MsolUser -MaxResults 1000 | where {$_.Department -eq "QA"} | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State | Format-Table

Get all email user by Contry "Vietnam"
Get-MsolUser -MaxResults 1000 | where {$_.Country -eq "Vietnam"} | Select-Object DisplayName,UserPrincipalName,Licenses,Department,Title,Country,State | Format-Table

Get view detail email 
Get-MsolUser -All | where {$_.DisplayName -eq "ABC DEFC"} | Select-Object DisplayName,UserPrincipalName,Department,Title,Country,State,WhenCreated | Format-Table

Display a list of users who haven’t changed their passwords for more than 90 days:
Get-MsolUser -MaxResults 20 | Where-Object { $_.LastPasswordChangeTimestamp -lt (Get-Date).AddDays(-90)} | Select-Object DisplayName,UserPrincipalName,LastPasswordChangeTimestamp,Licenses,PasswordNeverExpires | Format-Table

Change new password email with Powershell
Set-MsolUserPassword -UserPrincipalName user1@onmicrosoft.com -NewPassword P@SSw0rd!

Rebuild Index email O365 
New-MoveRequest -Identity user1@domain.com

Check status rebuild Index
Get-MoveRequest -Identity user1@domain.com

Get mail Inbox Forwarding
Get-Mailbox -ResultSize 2000 | select UserPrincipalName,ForwardingSmtpAddress,DeliverToMailboxAndForward | Export-csv Office365Forwards.csv -NoTypeInformation

Get email Forwarding
Get-Mailbox email@domain.com | FL DeliverToMailboxAndForward,ForwardingAddress,ForwardingSmtpAddress

Create new external contact 
New-MailContact -Name "My-gmail" -ExternalEmailAddress email@gmail.com


Display user not set Archive
Get-Mailbox -Filter {ArchiveStatus -Eq "None" -AND RecipientTypeDetails -eq "UserMailbox"}


Check for Archive status for some user

Get-mailbox usermail|fl ArchiveStatus

Get-Mailbox usermail |fl ArchiveStatus,Archivedatabase,Archiveguid

Enable Archive all 

Get-Mailbox -Filter {ArchiveStatus -Eq "None" -AND RecipientTypeDetails -eq "UserMailbox"} | Enable-Mailbox –Archive 

Enable one person 

Enable-Mailbox -Identity "user mail” -Archive 

Example : Enable-Mailbox -Identity "akom.b” -Archive 

Search and Delete mail by Subject

1. Search-Mailbox -Identity "email@domain.com" -SearchQuery 'Subject:"subject send mail"' -DeleteContent

2. Get-Mailbox -ResultSize unlimited | Search-Mailbox -SearchQuery 'Subject:"subject send mail"' -DeleteContent

Copy all email from one to another mail

Search-Mailbox "sourcmail" -TargetMailbox "targetmail" -TargetFolder "TargetFolder" -LogLevel Full

example: Search-Mailbox "email.a" -TargetMailbox "email.c" -TargetFolder "Email User" -LogLevel Full

Check archive In-place size

Ref:
get-msoluser
office-365-powershell-commands
how-to-install-microsoft-powershell-on-ubuntu
forward email
search and delete mail
copy mailbox

check disk size sort by bigger

sudo apt install tree
tree -ihafF /home | tr '[]' ' '|sort -k1hr|head -10

Install monitorix and reset password

sudo htpasswd -d -c /var/lib/monitorix/htpasswd admin

New password: 
Re-type new password: 
Adding password for user admin

Install monitorix

ปรับแต่งสคริป send mail alert โดยให้ส่งผ่าน smtp ที่ต้องการ

ปรับแต่งสคริป เพื่อให้ส่งเมลผ่านไปยัง smtp ที่เราทำไว้สำหรับส่งเมล ไม่ให้ส่งออกจากเครื่อง Server นั้น ๆ

สคริป

echo "Check all health hard disk backup complete" | mail -S smtp=IP:PORT -s "Check smart disk on Data Center was completed" -r noreply@domain.com -q /root/checkhealthdisk.txt -v admin@domain.com

คำอธิบาย

• echo "Check all health hard disk backup complete" ใส่ข้อความเข้าไปในส่วนล่างสุดของเมล
• mail -S smtp=IP:PORT ใส่ค่า smtp server ที่ต้องการเช่น 192.168.0.2 และพอร์ต 25 ตัวอย่าง 192.168.0.2:25
• -s "Check smart disk on Data Center was completed" คือ Subject mail
• -r noreply@domain.com คือ Sender mail
• -q /root/checkhealthdisk.txt คือ กรณีมีไฟล์ที่ต้องการแนบไปในเมล
• -v admin@domain.com คือ Receive mail (ผู้ร้บเมล)