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

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)

Unable to upgrade vCenter 6.5/6.7 to U2: Root password expired

As a Part of my pre-flight check for Vcenter upgrades i like to mount the ISO and go through the first 3 steps, during this I noticed the installer cannot connect to the source appliance with this error 

2019-05-01T20:05:02.052Z - info: Stream :: close
2019-05-01T20:05:02.052Z - info: Password not expired
2019-05-01T20:05:02.054Z - error: sourcePrecheck: error in getting source Info: ServerFaultCode: Failed to authenticate with the guest operating system using the supplied credentials.
2019-05-01T20:05:03.328Z - error: Request timed out after 30000 ms, url: https://vcenter.companyABC.local:443/
2019-05-01T20:05:09.675Z - info: Log file was saved at: C:\Users\MCbits\Desktop\installer-20190501-160025555.log

trying to reset via the admin interface or the DCUI didn’t work,  after digging around found a way to reset it by forcing the vcenter to boot in to single user mode

Procedure:

  1. Take a snapshot or backup of the vCenter Server Appliance before proceeding. Do not skip this step.
  2. Reboot the vCenter Server Appliance.
  3. After the OS starts, press e key to enter the GNU GRUB Edit Menu.
  4. Locate the line that begins with the word Linux.
  5. Append these entries to the end of the line: rw init=/bin/bash The line should look like the following screenshot:

After adding the statement, press F10 to continue booting 

Vcenter appliance will boot into single user mode

Type passwd to reset the root password

if you run into the following error message

"Authentication token lock busy"

you need to re-mount the filesystem in RW, which lets you change between read-only and read-write. this will allow you to make changes

mount -o remount,rw /

Until next time !!!