Most services should run in secure mode by adding SSL on top of them. The most popular services in RedHat 9 are imapd, pop3d, and sendmail. Anyway, default configuration of RedHat 9 will generate certificates with 365 days valid period. So that means you have to renew them once a year. The default certificate directory in RedHat 9 is /usr/share/ssl/certs. The first thing you need to do is to confirm that it has expired by using below command.

# openssl x509 -in sendmail.pem -text | grep Not
            Not Before: Apr  5 05:28:38 2005 GMT
            Not After : Apr  5 05:28:38 2006 GMT

Shortly, sendmail.pem has been already expired. Then I have to see its subject to make same one.

# openssl x509 -in sendmail.pem -text | grep Subject:

Now, it’s time to make new one using above information.

# rm sendmail.pem
# make sendmail.pem

Don’t forget to restart your services.

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