When you update OpenSSL, the software that currently has the ssl libraries loaded in memory do not automatically load the updated libraries.
A full system reboot resolves that problem, but sometimes that is not possible.
This command shows you all the software that has loaded the libraries, allowing you to restart only those services.
If you don't restart or reload after an update, the software might still be vulnerable to issues that the update fixed.
Make sure you have the lsof command installed.
Using the following command you get a list of services currently using libssl:
lsof | grep libssl | awk '{print $1}' | sort | uniq
This is the output:
directadm exim httpd imap-logi managesie nrpe php pop3-logi pure-ftpd spamd
Not all the filenames are complete but you can fill those in. If you leave out the last part of the command you can also see which specific library is in use:
lsof | grep libssl
Example output:
imap-logi 449 dovecot mem REG 202,1 539869 85375 /usr/lib64/libssl.so.1.0.0 httpd 876 apache mem REG 202,1 539869 85375 /usr/lib64/libssl.so.1.0.0 [...] spamd 13513 root mem REG 202,1 444168 85398 /usr/lib64/libssl.so.1.0.1e
Here you can see some services using a different library, those still need a restart.
Find all updated libraries and services using the old ones:
lsof | grep 'DEL.*lib' | cut -f 1 -d ' ' | sort -u