Ingress filtering

Imagine you are in a big house with many doors and windows. Your parents want to protect you and your family from bad guys who might try to come in through these doors or windows. So, they put a filter on the doors and windows and only allow people they know and trust to come in. This is called ingress filtering.

In computer networks, ingress filtering is a security technique that works like the filter on your doors and windows. It helps keep bad guys and unwanted traffic out of your network. The filter is like a gatekeeper that checks all the incoming traffic and only allows the traffic that matches certain criteria to pass through.

For example, if someone from outside your network tries to send you an email, the ingress filter will check the sender's address, the message content, and other details to see if it matches certain criteria that you have set up. If everything looks good, the filter will allow the email to go through. If not, the filter will block the email and prevent it from entering your network.

Ingress filtering is important for network security because it helps prevent malicious traffic from entering your network and potentially harming your computers and devices. However, it's not perfect and can sometimes block valid traffic if the filter is set up too strictly.

Overall, ingress filtering is like a security guard for your network's doors and windows, only allowing trusted traffic to enter and keeping out the rest.