How to import existing FW certificate?

Question

Good day all.. 
 I have a no-name Firewall running with pfSense and FW Certificate. 
 As my new Sophos XGS87 Firewall does not support pfSense I want to import the existing FW Certificate into Sophos. 
 Problem: as per Sophos website I have to import an "CSR" File. But I do only have the following file types ".crt." & ".key". 
 How can I import these files into the Sophos? 
 THX in advance for any clarification.

Vivek Jagad · Answer

Hi Vertical Technik , Thank you for reaching out to the community, yes as of now CSRs is a must, REF - Import a certificate . Not sure if a re-naming of an extension help ? But .CSR contains information such as the public key and common name required by a Certificate Authority to create and sign a certificate for the requester, the encoding could be PEM or DER (which is a binary encoding of an ASN.1 specified structure); Where as .CRT stands simply for certificate, usually an X509v3 certificate, again the encoding could be PEM or DER; a certificate contains the public key, but it contains much more information (most importantly the signature by the Certificate Authority over the data and public key, of course).