Is there a way to list all domains on an SAN/UCC SSL Certificate (ideally using command line on linux/os x)?

Clearly there must be some way to extract the data, since browsers can do it. Unfortunately, I can see the list but can't cut and paste it.

openssl x509 -text < $CERT_FILE


. . .
                DNS: . . .
. . .

where $CERT_FILE can have either the .pem or .crt extension.

Shell functions for viewing cert. files and checking that a cert. & key file match can be found here.

  • 3
    For posterity, this is the full command I used, since I was doing it for another server: openssl s_client -showcerts -connect www.example.org:443 | openssl x509 -text Sep 10 '12 at 13:39
  • 3
    To get a clean space delimited list of domains you can pass it through grep and sed like so openssl x509 -text < $CRT | grep 'DNS:' | sed 's/\s*DNS:\([a-z0-9.\-]*\)[,\s]\?/\1 /g'
    – Geoffrey
    Apr 28 '17 at 8:49

You can list the domains with this command (tested on linux):

cat cert.pem | openssl x509 -text | grep DNS

If you just want to see the SANs, grep DNS: is the obvious solution.

If you want to have a cleaner list to process further, you can use this Perl regex to extract just the names : @names=/\sDNS:([^\s,]+)/g

For example:

true | openssl s_client -connect example.com:443 2>/dev/null \
| openssl x509 -noout -text \
| perl -l -0777 -ne '@names=/\bDNS:([^\s,]+)/g; print join("\n", sort @names);'

Which would output this:


So you could pipe that to while read name; do echo "processing $name ..."; done etc.

Or for a comma-separated list on one line, replace join("\n", with join(",",

(The -0777 switch for perl makes it read the whole input at once instead of line by line)

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