openssl the command is amazing

There are lots of things you can do with the openssl command that I didn't know about:

Verify if numbers are prime:

$ openssl prime 119054759245460753
1A6F7AC39A53511 is not prime
$  

Encrypt a file with your favorite cipher:

openssl list-cipher-commands

base64 encode a file

openssl enc -base64 -in file.txt

Generate a shadow-style password hash:

$ openssl passwd -1 MySecret
$1$sXiKzkus$haDZ9JpVrRHBznY5OxB82.
$ 

Many others. I never knew it could do some much. Thanks madboa.com.

Also, I played around with openssl while updating certificates for about 30 web servers. I was able to check that the new cert was installed correctly on all of the hosts easily looking at that host's SSL finger prints as served from Apache:

echo EOF | openssl s_client -connect $host:443 -showcerts | openssl x509 -fingerprint -noout -md5

The above fits well into a bash loop which can be run before and after you replace the certs:

for x in `cat vhosts.txt`; do 
   echo "vhost: $x";echo EOF | openssl \
     s_client -connect $x:443 -showcerts \
     | openssl x509 -fingerprint -noout \
     -md5; 
done 
| egrep "vhost|Fingerprint" > finger_prints.txt

You can then diff the finger prints files to verify that they're what you're expecting them to be.