Abstract: A disclosed method may include (1) receiving a packet at a tunnel driver in kernel space on a routing engine of a network device, (2) identifying, at the tunnel driver, metadata of the packet that indicates whether at least one firewall filter had already been correctly applied to the packet before the packet arrived at the tunnel driver, (3) determining, based at least in part on the metadata of the packet, that the firewall filter had not been correctly applied to the packet before the packet arrived at the tunnel driver, and then in response to determining that the firewall filter had not been correctly applied to the packet, (4) invoking at least one firewall filter hook that applies at least one firewall rule on the packet before the packet is allowed to exit kernel space on the routing engine. Various other apparatuses, systems, and methods are also disclosed.

Abstract: A disclosed method may include (1) receiving a packet at a tunnel driver in kernel space on a routing engine of a network device, (2) identifying, at the tunnel driver, metadata of the packet that indicates whether at least one firewall filter had already been correctly applied to the packet before the packet arrived at the tunnel driver, (3) determining, based at least in part on the metadata of the packet, that the firewall filter had not been correctly applied to the packet before the packet arrived at the tunnel driver, and then in response to determining that the firewall filter had not been correctly applied to the packet, (4) invoking at least one firewall filter hook that applies at least one firewall rule on the packet before the packet is allowed to exit kernel space on the routing engine. Various other apparatuses systems, and methods are also disclosed.

Abstract: A disclosed method for applying firewall rules on packets in kernel space on network devices may include (1) intercepting, via a socket-intercept layer in kernel space on a routing engine of a network device, a packet that is destined for a remote device and then, in response to intercepting the packet in kernel space on the routing engine, (2) identifying an egress interface index that specifies an egress interface that (A) is external to kernel space and (B) is capable of forwarding the packet from the network device to the remote device and (3) applying, on the packet in kernel space, at least one firewall rule based at least in part on the egress interface index before the packet egresses from the routing engine. Various other apparatuses, systems, and methods are also disclosed.