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We have these separate sites: a.example.com, b.example.com, and c.example.com. Now we want to add an SSL Certificate to these sites.

There is a pretty good tutorial for this, but I have a couple questions:

  1. Can I use one SSL certificate on these three sites?

  2. If the answer of 1 is yes, do I need to change the CSR generating commands for this?

list the commands below

#Must do these as root.
openssl genrsa -des3 -out example.com.key 2048
#you will be prompted to enter password
openssl rsa -in example.com.key -out example.com.key.nopass
#you will be prompted to enter password you created in last step
openssl req -new -key example.com.key.nopass -out example.com.csr
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It really depends on what CA you are using. For example, many of them ignore the fields in the request except for the public key. But the short answer is that this is what a wildcard SSL certificate is for. –  David Schwartz Sep 4 '12 at 10:03
@David There is a Common Name option in generating, you mean I just set it to *.example.com? –  mitnk Sep 4 '12 at 10:07
Ask your CA. They most likely ignore it. They may want it to be example.com, but *.example.com is typical. –  David Schwartz Sep 4 '12 at 10:08
Okey, Thank you, David –  mitnk Sep 4 '12 at 10:10

1 Answer 1

If the a, b and c resolves to the same ip, you can create a certificate with alias names.

E.g. add the folowing to your request:

# Instead the additional names are form entries on web
# pages where one requests the certificate...
subjectAltName          = @alt_names
DNS.1_default           = a.example.com
DNS.2_default           = b.example.com
DNS.3_default           = c.example.com
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