Use Mailx to send emails using office 365

just something that came up while setting up a monitoring script using mailx, figured ill note it down here so i can get it to easily later when I need it 😀

Important prerequisites

  • You need to enable smtp basic Auth on Office 365 for the account used for authentication
  • Create an App password for the user account
  • nssdb folder must be available and readable by the user running the mailx command

Assuming all of the above prerequisite are $true we can proceed with the setup

Install mailx

RHEL/Alma linux

sudo dnf install mailx

NSSDB Folder

make sure the nssdb folder must be available and readable by the user running the mailx command

certutil -L -d /etc/pki/nssdb

The Output might be empty, but that’s ok; this is there if you need to add a locally signed cert or another CA cert manually, Microsoft Certs are trusted by default if you are on an up to date operating system with the local System-wide Trust Store

Reference – RHEL-sec-shared-system-certificates

Configure Mailx config file

sudo nano /etc/mail.rc

Append/prepend the following lines and Comment out or remove the same lines already defined on the existing config files

set smtp=smtp.office365.com
set smtp-auth-user=###[email protected]###
set smtp-auth-password=##Office365-App-password#
set nss-config-dir=/etc/pki/nssdb/
set ssl-verify=ignore
set smtp-use-starttls
set from="###[email protected]###"

This is the bare minimum needed other switches are located here – link

Testing

echo "Your message is sent!" | mailx -v -s "test" [email protected]

-v switch will print the verbos debug log to console

Connecting to 52.96.40.242:smtp . . . connected.
220 xxde10CA0031.outlook.office365.com Microsoft ESMTP MAIL Service ready at Sun, 6 Aug 2023 22:14:56 +0000
>>> EHLO vls-xxx.multicastbits.local
250-MN2PR10CA0031.outlook.office365.com Hello [167.206.57.122]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
>>> STARTTLS
220 2.0.0 SMTP server ready
>>> EHLO vls-xxx.multicastbits.local
250-xxde10CA0031.outlook.office365.com Hello [167.206.57.122]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH LOGIN XOAUTH2
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
>>> AUTH LOGIN
334 VXNlcm5hbWU6
>>> Zxxxxxxxxxxxc0BmdC1zeXMuY29t
334 UGsxxxxxmQ6
>>> c2Rxxxxxxxxxxducw==
235 2.7.0 Authentication successful
>>> MAIL FROM:<###[email protected]###>
250 2.1.0 Sender OK
>>> RCPT TO:<[email protected]>
250 2.1.5 Recipient OK
>>> DATA
354 Start mail input; end with <CRLF>.<CRLF>
>>> .
250 2.0.0 OK <[email protected]> [Hostname=Bsxsss744.namprd11.prod.outlook.com]
>>> QUIT
221 2.0.0 Service closing transmission channel 

Now you can use this in your automation scripts or timers using the mailx command

#!/bin/bash

log_file="/etc/app/runtime.log"
recipient="[email protected]"
subject="Log file from /etc/app/runtime.log"

# Check if the log file exists
if [ ! -f "$log_file" ]; then
  echo "Error: Log file not found: $log_file"
  exit 1
fi

# Use mailx to send the log file as an attachment
echo "Sending log file..."
mailx -s "$subject" -a "$log_file" -r "[email protected]" "$recipient" < /dev/null
echo "Log file sent successfully."

Secure it

sudo chown root:root /etc/mail.rc
sudo chmod 600 /etc/mail.rc

The above commands change the file’s owner and group to root, then set the file permissions to 600, which means only the owner (root) has read and write permissions and other users have no access to the file.

Use Environment Variables: Avoid storing sensitive information like passwords directly in the mail.rc file, consider using environment variables for sensitive data and reference those variables in the configuration.

For example, in the mail.rc file, you can set:

set smtp-auth-password=$MY_EMAIL_PASSWORD

You can set the variable using another config file or store it in the Ansible vault during runtime or use something like Hashicorp.

Sure, I would just use Python or PowerShell core, but you will run into more locked-down environments like OCI-managed DB servers with only Mailx is preinstalled and the only tool you can use 🙁

the Fact that you are here means you are already in the same boat. Hope this helped… until next time

Change the location of the Docker overlay2 storage directory

If you found this page you already know why you are looking for this, your server /dev/mapper/cs-root is filled due to /var/lib/docker taking up most of the space

Yes, you can change the location of the Docker overlay2 storage directory by modifying the daemon.json file. Here’s how to do it:

Open or create the daemon.json file using a text editor:

sudo nano /etc/docker/daemon.json

{
    "data-root": "/path/to/new/location/docker"
}

Replace “/path/to/new/location/docker” with the path to the new location of the overlay2 directory.

If the file already contains other configuration settings, add the "data-root" setting to the file under the "storage-driver" setting:

{
    "storage-driver": "overlay2",
    "data-root": "/path/to/new/location/docker"
}

Save the file and Restart docker

sudo systemctl restart docker

Don’t forget to remove the old data

rm -rf /var/lib/docker/overlay2

Azure AD Sync Connect No-Start-Connection status

Issue

Received the following error from the Azure AD stating that Password Synchronization was not working on the tenant.

When i manually initiate a delta sync, i see the following logs

"The Specified Domain either does not exist or could not be contacted"

(click to enlarge)

Checked the following

  • Restarted ADsync Services
  • Resolve the ADDS Domain FQDN and DNS – Working
  • Test required ports for AD-sync using portqry – issues with the Primary ADDS server defined on the DNS values

Root Cause

Turns out the Domain controller Defined as the primary DNS value was pointing was going thorough updates, its responding on the DNS but doesn’t return any data (Brown-out state)

Assumption

when checking DNS since the DNS server is connecting, Windows doesn’t check the secondary and tertiary servers defined under DNS servers.

This might happen if you are using a ADDS server via a S2S tunnel/MPLS when the latency goes high

Resolution

Check make sure your ADDS-DNS servers defined on AD-SYNC server are alive and responding

in my case i just updated the “Primary” DNS value with the umbrella Appliance IP (this act as a proxy and handle the fail-over)

Hybrid Exchange mailbox On-boarding : Target user already has a primary mailbox – Fix

During an Office 365 migration on a Hybrid environment with AAD Connectran into the following scenario:

  • Hybrid Co-Existence Environment with AAD-Sync
  • User [email protected] has a mailbox on-premises. Jon is represented as a Mail User in the cloud with an office 365 license
  • [email protected] had a cloud-only mailbox prior to the initial AD-sync was run
  • A user account is registered as a mail-user and has a valid license attached
  • During the office 365 Remote mailbox move, we end up with the following error during validation and removing the immutable ID and remapping to on-premise account won’t fix the issue
Target user 'Sam fisher' already has a primary mailbox.
+ CategoryInfo : InvalidArgument: (tsu:MailboxOrMailUserIdParameter) [New-MoveRequest], RecipientTaskException
+ FullyQualifiedErrorId : [Server=Pl-EX001,RequestId=19e90208-e39d-42bc-bde3-ee0db6375b8a,TimeStamp=11/6/2019 4:10:43 PM] [FailureCategory=Cmdlet-RecipientTaskException] 9418C1E1,Microsoft.Exchange.Management.Migration.MailboxRep
lication.MoveRequest.NewMoveRequest
+ PSComputerName : Pl-ex001.Paladin.org

It turns out this happens due to an unclean cloud object on MSOL, This is because Exchange online keeps pointers that indicate that there used to be a mailbox in the cloud for this user

Option 1 (nuclear option)

to fix this problem was to delete *MSOL User Object* for Sam and re-sync it from on-premises. This would delete [email protected] from the cloud – but it will delete him/her from all workloads, not only Exchange. This is problematic because Sam is already using Teams, One-drive, SharePoint.

Option 2

Clean up only the office 365 mailbox pointer information

PS C:\> Set-User [email protected] -PermanentlyClearPreviousMailboxInfo 
Confirm
Confirm
Are you sure you want to perform this action?
Delete all existing information about user "[email protected]"?. This operation will clear existing values from
Previous home MDB and Previous Mailbox GUID of the user. After deletion, reconnecting to the previous mailbox that
existed in the cloud will not be possible and any content it had will be unrecoverable PERMANENTLY. Do you want to
continue?
[Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is "Y"): a

Executing this leaves you with a clean object without the duplicate-mailbox problem,

in some cases when you run this command you will get the following output 

 “Command completed successfully, but no user settings were changed.”

If this happens

Remove the license from the user temporarily and run the command to remove previous mailbox data

then you can re-add the license 

 

“System logs on hosts are stored on non-persistent storage” message on VCenter

Ran into this pesky little error message recently, on a vcenter environment

If the logs are stored on a local scratch disk, vCenter will display an alert stating –  “System logs on host xxx are stored on non-persistent storage”

Configure ESXi Syslog location – vSphere Web Client

Vcenter > Select “Host”> Configure > Advance System Settings

Click on Edit and search for “Syslog.global.logDir”

Edit the value and in this case, I’m going to use the local data store (Localhost_DataStore01) to store the syslogs.

You can also define a remote syslog server using the “Syslog.global.LogHost” setting

Configure ESXi Syslog location – ESXCLI

Ssh on to the host

Check the current location

esxcli system syslog config get

*logs stored on the local scratch disk

Manually Set the Path

esxcli system syslog config set –logdir=/vmfs/directory/path

you can find the VMFS volume names/UUIDs under  –

/vmfs/volumes

remote syslog server can be set using

esxcli system syslog config set –loghost=’tcp://hostname:port’

Load the configuration changes with the syslog reload command

esxcli system syslog reload

The logs will immediately begin populating the specified location.