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: The disclosed apparatus may include (1) flagging, at a packet filter within a network device, a packet to be discarded instead of passed to a processing unit within the network device, (2) determining that the packet is part of a set of related packets that includes at least one additional packet destined at least intermediately for the network device, (3) identifying, by monitoring incoming packets received at the packet filter, the additional packet within the set of related packets, and then (4) discarding, due to the additional packet being included within the set of related packets, the additional packet instead of passing the additional packet to the processing unit. Various other apparatuses, systems, and methods are also disclosed.

Abstract: A disclosed method may include (1) determining that a packet traversing a network device has been selected for conditional tracing by (A) comparing a characteristic of the packet against a firewall rule that calls for all packets exhibiting the characteristic to be conditionally debugged while traversing the network device and (B) determining, based at least in part on the comparison, that the firewall rule applies to the packet due at least in part to the packet exhibiting the characteristic, (2) tracing a journey of the packet within the network device in response to the determination by collecting information about the packet's journey through a network stack of the network device, and then (3) performing at least one action on the network device based at least in part on the information collected about the packet's journey through the network stack. Various other systems, methods, and computer-readable media are also disclosed.

Abstract: A network device may obtain policer configuration information. The network device may determine, based on the policer configuration information, a traffic rate limit associated with a traffic protocol type. The network device may obtain, based on the traffic protocol type, networking data associated with the traffic protocol type. The network device may determine, based on the networking data, an expected traffic rate associated with the traffic protocol type. The network device may update, based on the expected traffic rate, the traffic rate limit. The network device may cause traffic associated with the traffic protocol type to be policed based on the updated traffic rate limit.

Abstract: A network device may detect, from an application associated with a user space of the network device, a request to configure a firewall provided by a kernel of the network device with a rule. The network device may intercept the request to configure the firewall before the firewall is configured with the rule. The network device, based on intercepting the request to configure the firewall, may analyze the rule to determine whether the rule modifies a critical functionality of the firewall. The network device may reject the request to configure the firewall based on determining that the rule modifies the critical functionality of the firewall.

Abstract: The disclosed method may include (1) determining a size of a packet received at a network device, (2) identifying, within a plurality of packet policers that track rates of packets with various sizes received at the network device, a packet policer that tracks rates of packets whose sizes are within a range that includes the size of the packet, (3) determining a current rate of packets tracked by the packet policer, and then (4) handling the packet based at least in part on whether the current rate exceeds a threshold rate. Various other apparatuses, systems, and methods are also disclosed.

Abstract: A socket-intercept layer in kernel space on a network device may intercept a packet destined to egress out of the network device. The socket-intercept layer may then query a routing daemon for the Maximum Transmission Unit (MTU) value of the interface out of which that packet is to egress from the network device. In response to this query, the routing daemon may provide the socket-intercept layer with the MTU value of that interface. A tunnel driver in kernel space may identify the size of the packet and fragment the packet into segments whose sizes are each less than or equal to the MTU value of the interface. The tunnel driver may then push the segments of the packet to a packet forwarding engine on the network device. In turn, the packet forwarding engine may forward the segments of the packet to the corresponding destination via the interface.

Abstract: Filter synchronization across a restart of a firewall filter application for converting filter information for filters into corresponding iptables filter table rules, is ensured by (1) computing a hash value for filter information derived from a filter using the filter or information derived from the filter, (2) determining an iptables filter table rule using the filter information for the filter, (3) associating the hash value with the corresponding iptables filter table rule, and (4) adding the determined iptables filter table rule and the hash value to iptables filter table rules in a Linux kernel.

Abstract: A method includes receiving, by processing circuitry of a first network device, an indication of a logical address associated with an interface to a second network device and adding, by the processing circuitry, an entry to a forwarding table of the first network device, the entry in the forwarding table specifying the logical address. The method further includes adding, by the processing circuitry, an entry to a resolver database of the first network device to which the entry in the forwarding table specifying the logical address points and resolving, by the processing circuitry, the logical address to a hardware address of the second network device.

Abstract: A disclosed method may include (1) determining that a packet traversing a network device has been selected for conditional tracing by (A) comparing a characteristic of the packet against a firewall rule that calls for all packets exhibiting the characteristic to be conditionally debugged while traversing the network device and (B) determining, based at least in part on the comparison, that the firewall rule applies to the packet due at least in part to the packet exhibiting the characteristic, (2) tracing a journey of the packet within the network device in response to the determination by collecting information about the packet's journey through a network stack of the network device, and then (3) performing at least one action on the network device based at least in part on the information collected about the packet's journey through the network stack. Various other systems, methods, and computer-readable media 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.

Abstract: A device may receive, from the packet processing component and through an internal interface, a packet that includes a virtual routing and forwarding (VRF) interface identifier associated with a VRF interface of a virtual device. The internal interface may be associated with multiple external interfaces. The device may modify a value identifying an incoming interface via which the packet is received after receiving the packet that includes the VRF interface identifier. The modified value may be associated with the virtual device, and the modified value may allow an upper communication layer to determine that the packet is associated with the virtual device. The device may provide the packet to the upper communication layer after modifying the value identifying the incoming interface via which the packet is received to permit the upper communication layer to forward the packet to a destination.

Abstract: A device may receive, by a kernel of the device and from a loadable kernel module of the device, information that instructs the kernel to invoke a callback function associated with the loadable kernel module based on an execution of a hook of the kernel. The device may receive, by the kernel of the device and from an application of the device, a socket application programming interface (API) call. The socket API call may include control information. The device may execute, by the kernel of the device, the hook based on receiving the socket API call. The device may invoke, by the kernel of the device, the callback function associated with the loadable kernel module based on executing the hook to permit a functionality associated with the callback function to be provided. The kernel may provide the control information, associated with the socket API call, to the callback function as an argument.

Abstract: A disclosed method may include (1) detecting, at a network stack of a network device, a packet that (A) is destined at least intermediately for a network interface of the network device and (B) has been flagged by the network stack to be dropped instead of forwarded to the network interface based on at least one characteristic of the packet, (2) instead of dropping the packet, forwarding the packet to an alternative network interface of the network device that analyzes content of packets, (3) identifying, at the alternative network interface, the characteristic of the packet, and then (4) executing, based on the characteristic of the packet, at least one action in connection with the packet that improves the performance of the network device. Various other apparatuses, systems, and methods are also disclosed.

Abstract: The disclosed apparatus may include (1) a physical routing engine that comprises (A) a socket-intercept layer, stored in kernel space, that (I) intercepts a packet that is destined for a remote device and (II) queries, in response to intercepting the packet in kernel space, a routing daemon in user space for an MTU value of an egress interface that is to forward the packet from the network device to the remote device and (B) a tunnel driver, stored in kernel space, that fragments the packet into segments whose respective sizes each comply with the MTU value of the egress interface and (2) a physical packet forwarding engine that forwards the segments of the packet to the remote device by way of the egress interface. 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.

Abstract: A device may receive information related to an operation of the device during each of multiple time intervals. The device may store, for each time interval of the multiple time intervals, the information in a respective slot of a circular buffer that includes multiple slots. The circular buffer may be used to store a historical record of the information in one or more of the multiple slots. The historical record may be provided from the circular buffer during a dump of the device. The device may provide the historical record during the dump of the device based on storing the historical record of the information in the one or more of the multiple slots.

Abstract: The disclosed method may include (1) receiving a synchronize message from a computing device to initiate synchronization between the computing device and a server with respect to a communication protocol, (2) notifying an application in user space on the server of the synchronize message such that the application in user space selects at least one attribute to be applied to a communication session resulting from the synchronization between the computing device and the server, (3) sending a synchronize acknowledgment that identifies the attribute selected by the application in user space to the computing device to further the synchronization between the computing device and the server, and then (4) establishing the communication session with the attribute selected by the application in user space upon receiving an acknowledgment message from the computing device to complete the synchronization. Various other methods, systems, and apparatuses are also disclosed.

Abstract: The disclosed computer-implemented method may include (1) identifying, in kernel space on a network device, a packet that is destined for a remote device, (2) passing, along with the packet, metadata for the packet to a packet buffer in kernel space on the network device, (3) framing, by the kernel module in kernel space, the packet such that the packet egresses via a tunnel interface driver on the network device, (4) encapsulating, by the tunnel interface driver, the packet with the metadata, and then (5) forwarding, by the tunnel interface driver, the packet to the remote device based at least in part on the metadata with which the packet was encapsulated. Various other methods, systems, and computer-readable media are also disclosed.