Terminating Actions for Firewall Filters

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Sure, I'd be happy to provide a detailed explanation of the three terminating actions for firewall filters!

Firewall filters are used in Juniper Networks Junos operating system to control and manage network traffic. Firewall filters are typically applied to interfaces on a device, and they can be used to permit, deny, or modify traffic passing through that interface based on specific criteria, such as source or destination IP address, protocol type, and port number.

When a packet matches the criteria specified in a firewall filter, the firewall filter takes a terminating action, which determines what happens to the packet. There are several possible terminating actions that a firewall filter can take, but the three most common are:

1. Reject: When a packet matches a firewall filter with the "reject" terminating action, the packet is dropped and an ICMP message is sent back to the source of the packet to inform it that the packet was rejected. This ICMP message can be configured to include specific information about why the packet was rejected, such as the reason for the rejection or the firewall filter rule that caused the rejection.

2. Drop: When a packet matches a firewall filter with the "drop" terminating action, the packet is simply discarded and no notification is sent back to the source of the packet. This can be useful in situations where you want to silently discard unwanted traffic without notifying the sender.

3. Discard: The "discard" terminating action is similar to the "drop" action, but it allows you to specify a reason for the discard. This can be useful for troubleshooting purposes, as it allows you to identify which packets were discarded and why they were discarded.

Note that "permit" and "accept" are not terminating actions for firewall filters. When a packet matches a firewall filter with the "permit" or "accept" action, the packet is allowed to pass through the firewall filter and continue on its way.