Subordinate CA creation for SSL Decryption

[Steve27596]

Hello,

   I am attempting to set up SSL Decryption on a new firewall and trying to create a Subordinate CA with our internal Microsoft Certificate Services.  I am in the process of generating the CSR on the PA, but I am a little confused on what the Common Name should be.

  Should it be the Inside interface IP, Outside interface IP, the AD domain controller name?  I am stumped.  If someone could give me a pointer, I would apprecaite it.

Thanks,

  Steve

[TranceforLife]

In the Common Name field, enter the FQDN (recommended) or IP address of the interface where you will configure the service that will use this certificate. So FQDN of the inside interface (client facing interface) is the way to go. But for sure other members will give you a better advice as I am not a great fan of the SSL decryption 😄

[gwesson · Accepted solution]

Functionally, the CN won't really matter. The user is presented a server certificate that matches the CN and SAN fields of the destination server, but it's signed by the CA you're creating. Some admins choose something descriptive like "SSL-TLS Inspection", while others will simply use something like "MyCompany Security Team".

It won't actually matter, it's really just a matter of preference. It shows up as the signer, so most users won't even see it unless they have a habit of checking the certificate chain. 

Edit: You'll want to include the "Host Name" option as well. Chrome 57 (I think) has deprecated the CN field. If your CA doesn't have a SAN (using the Host Name field) it may complain. I haven't tested it, but it's worth considering.

[TranceforLife]

SSL Certs are always being an interesting subject. Doesn't look complex but easy to get confused (at least for me :D)

Thanks for the explanation