Certificate Install/Combination

Question

I am trying to install a comodo positive ssl certificate on my UTM, and I have generated the key and csr following this: 
 http://community.sophos.com/kb/en-US/115976 
 I then sent the csr to the cert agency and they sent back 4 files: 
 AddTrustExternalCARoot.crt 
 COMODOAddTrustCA.crt 
 COMODORSADomainValidationSecureServerCA.crt 
 sub.domain.com.crt 
 Do I need to use all these files? If so in what order do I need to put them when I combine them. 
 I found this: https://www.sophos.com/en-us/support/knowledgebase/118084.aspx 
 but it doesn't say what files to combine/use... 
 Can anyone offer a little more clarity/guidance?

BlueRue · Accepted Answer

So I combined all the Comodo certs in this order using the cat command: cat sub.domain.com.crt COMODORSADomainValidationSecureServerCA.crt COMODORSAAddTrustCA.crt >combined.crt 
 Edit: I have removed the AddTrustExternalCARoot.crt in the combination process I heard it was recommended to leave it out unless you get error so I recombined without it and I am not receiving any errors.. So I am leaving it out you may add it if you choose, if you choose to add it the list looks like this: 
 cat sub.domain.com.crt COMODORSADomainValidationSecureServerCA.crt COMODORSAAddTrustCA.crt AddTrustExternalCARoot.crt >combined.crt Once they where combined I then used the following command to make a .p12 file : openssl pkcs12 -export -in combined.crt -inkey privkey.pem -out sub.domain.com.p12 I imported the .p12 file into the "Certificate" area and I was then able to select the Comodo Cert for the WebAdmin/User Portal. Because the combined.crt contains all the authority validation certs you do not have to import them into the certificate authority area.

vilic · Answer

You should import first three certificates (root and two intermediates) into Certificate Management -> Certificate Authority: 
 sub.domain.com.crt should be imported into Certificate Management -> Certificates.