How to create a cer file from a pfx

If you want to extract client certificates, you can use OpenSSL's PKCS12 tool.

openssl pkcs12 -in input.pfx -out mycerts.crt -nokeys -clcerts

The command above will output certificate(s) in PEM format. The ".crt" file extension is handled by both macOS and Window.
You mention ".cer" extension in the question which is conventionally used for the DER encoded files. A binary encoding. Try the ".crt" file first and if it's not accepted, easy to convert from PEM to DER:


openssl x509 -inform pem -in mycerts.crt -outform der -out mycerts.cer

How to create .pfx file

In order to use in IIS (version 8 ) https we need to import a certificate which has to be associated to https binding .

If you buy or get a free ssl certificate you can convert it to a pfx file like this :

openssl pkcs12 -export -out domain.name.pfx -inkey domain.name.key -in domain.name.crt

Openssl can be downloaded from here.

If you have a root CA or intermediate certificate you can append it by supplying multiple -in parameter:

openssl pkcs12 -export -out domain.name.pfx -inkey domain.name.key -in domain.name.crt -in intermediate.crt -in rootca.crt

Now that you have the pfx you can just import it in IIS 8 and use it .