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→Perform the following steps on your VM2 (pri-dns)
== Perform the following steps on your VM2 (pri-dns)==
* login to your VM2 as the student user.
* Find out the version of the postfix rpm installed on the available to your CentOS 8.x system with one of the following commands and keep a record of it.
<pre>
rpm -q postfix
grep -w smtp /etc/services
</pre>
* Note that the file /etc/services is used on a Linux system to resolve TCP/UDP service names to TCP/UDP port numbers.* Make sure that the postfix.service is running on your VM2, if not, start the postfix.service and confirm that it is running properly.* Beside the systemctl command, there are two more places (or commands) you can use to confirm whether there is a an SMTP server running on your system: the "ss -at" and "ps -ef" command:
* Try the following command pipe line and look for the SMTP port number under the "Local Address" column and record the line(s) for future reference.
<pre>
ss -at | grep -e "Local Address" -e "smtp"
ss -atn | grep -e "Local Addres" -e [smtp port number]
</pre>
* Note that if the Local Address shown is 127.0.0.1 only, your SMTP server will not be reachable by other machines.