IDS ensure a security policy in every single packet passing through the network.
Snort is an open-source , lightweight tool which captures every detail of packet passing through the network and generate alerts if any one packets matches the signatures inserted given by the company.
Intrusion detection systems fall into one of three categories: Host Based Intrusion Detection Systems (HIDS), Network Based Intrusion Detection Systems (NIDS), and hybrids of the two.
SNORT can be used to monitor the traffic that goes in and out of a network.
It will monitor traffic in real time and issue alerts to users when it discovers potentially malicious packets or threats on Internet Protocol (IP) networks.