Getting started with Neo4J and security data analysis

Posted on by David Vassallo

During a recent study module for a MSc I am undertaking we discussed the importance of continuous monitoring of data sources as part of a sound security defensive strategy. This lead me down a very interesting path, eventually culminating in my discovery of an entire subset in security discipline many refer to as "Security visualization". There are … Continue reading Getting started with Neo4J and security data analysis

Email Error: 450 Client host rejected

Posted on by David Vassallo

A couple of our clients sometimes have issues when sending email, with a returned non-delivery report stating the following: Peer server rejected email: 450 Client host rejected: 'cannot find your hostname' It turns out this is a very strict check (usually performed by postfix), that is controlled via the directive reject_unknown_client_hostname in the postfix configuration. The documentation … Continue reading Email Error: 450 Client host rejected