How do I make my own bundle file from CRT files?

Answer: You may do this using your favorite text editor or by using the command line.

Example:
# Root CA Certificate – AddTrustExternalCARoot.crt
# Intermediate CA Certificate 1 – UTNAddTrustSGCCA.crt
# Intermediate CA Certificate 2 – ComodoUTNSGCCA.crt
# Intermediate CA Certificate 3 – EssentialSSLCA_2.crt
# Your SSL Certificate – yourDomain.crt

Note: You will not need your SSL certificate for this exercise.

GUI Text Editor

1. Open all files in a text editor. (Remember, not your domain certificate.)
2. Create a new blank text file.
3. Copy contents of all files in reverse order and paste them into the new file.
Example: Intermediate 3, Intermediate 2, Intermediate 1, Root Certificate.
4. Save newly created file as ‘yourDomain.ca-bundle‘.

Command Line

Linux or UNIX-like Operating Systems:
— cat EssentialSSLCA_2.crt ComodoUTNSGCCA.crt UTNAddTrustSGCCA.crt AddTrustExternalCARoot.crt > yourDomain.ca-bundle

Windows or DOS:
— copy EssentialSSLCA_2.crt + ComodoUTNSGCCA.crt + UTNAddTrustSGCCA.crt + AddTrustExternalCARoot.crt yourDomain.ca-bundle

Note: ‘yourDomain.ca-bundle‘ is only a place holder file name. You may call it anything you want.