As part of the Heartbleed event, I have upgraded OpenSSL, reissued and replaced certificates and revoked the old ones and changed passwords however, I am also seeing advice to invalidate all session cookies (https://security.stackexchange.com/a/55089/18057) but I cannot find out how to do this.
Does this just apply to PHP sessions, for example, or is it more than this? What do I need to do to ensure all session keys and cookies are invalidated?
Thanks