How to renew an expired self-signed certificate (SSL/TLS, for Postfix)?

Question

linux

for Postfix (type SSL / TLS, encrypted password) the self-signed certificate has ended, as I understand it in the openssl.cnf configs, you can simply increase the validity period and re-sign the current certificates?

Answer 1

The validity period is set when the certificate is created. It doesn't matter if it's via the command line or in the openssl.cnf file. Certificates will have to be re-created/re-signed.

Answer 2

And why use a self-signed one if you have Let's Encrypt and WoSign (we don't consider StartSSL as unreliable, after their circus with issuing certificates to almost any domain to any person)?

Answer 3

The certificate cannot be re-signed, renewed or changed at all - all the information in it is unchanged. If the validity period has expired - the certificate is simply re-issued, since it is self-signed - there should be no problems with this.