Illustration - Gmail Smtp Certificate Chain - LEGRAND Raritan PX3TS User Manual

Appendix J: Additional PX3TS Information
openssl s_client -showcerts -connect smtp.gmail.com:465
862
It is NOT recommended to upload the server certificate to the receiver except
when it is a self-signed certificate. Using self-signed server certificates is also
not recommended and may not even work in all cases.
Order of the chain in the certificate file:
The order of a certificate chain's content in the certificate file uploaded to the
receiver must look like the following.
•
The top is the final intermediate certificate of the chain "B" if you have to
upload a partial chain.
•
The bottom is always the root certificate "A".
•
When copying multiple certificates to a single file, make sure you also copy
the lines of BEGIN CERTIFICATE and END CERTIFICATE from each
certificate.

Illustration - GMAIL SMTP Certificate Chain

If you will apply your company's SMTP service to PX3TS, ignore this GMAIL
illustration topic. Simply contact your IT department to retrieve the
appropriate certificate (chain) file and upload it to the PX3TS.
This section illustrates the upload of a TLS "root" certificate for using the
"gmail.com" SMTP service.
Unlike normal TLS websites, where you can easily find its server certificate by
using a Web browser, the method to find an SMTP server's certificate is more
difficult, which requires appropriate tools and sufficient technical knowledge.
For example, you may have to use the openssl command as illustrated below to
retrieve the certificate of the GMAIL SMTP server.
Step 1 -- Find the certificate(s) the SMTP server has:
1. Issue the following command in the appropriate command line application.
▪
In the following example command, we assume the server
"smtp.gmail.com" provides the SMTP service. You can change the
server name, port number, command or even the tool as needed.
Alternative: To view the certificate chain instead of all certificates, you can
remove the "-showcerts" option from the above command.