DoS policy hardware acceleration

DoS policy hardware acceleration offloads processing required for IPv4 and IPv6 DoS policies, interface policies, and access control list (ACL) policies to NP7 processors. Sessions for these types of policies bypass the CPU and are sent directly to NP7 processors.

Use the following command to enable DoS policy offloading:

config system settings

set policy-offload-level dos-offload

end

This command enable DoS policy hardware acceleration for the FortiGate or for the current VDOM if multiple VDOMs are enabled.

You can also use the following command to configure some DoS policy hardware acceleration options:

config system npu

config dos-options

set npu-dos-meter-mode {global | local}

set npu-dos-tpe-mode {disable | enable}

end

npu-dos-meter-mode select global (the default) to configure DoS metering across all NP7 processors. Select local to configure metering per NP7 processor.

DoS metering controls how the threshold for each configured anomaly is distributed among NP7 processors. For example, for a FortiGate with four NP7 processors and the tcp_syn_flood anomaly threshold set to 400. If npu-dos-meter-mode is set to global, the threshold of 400 is divided between the NP7 processors and the tcp_syn_flood threshold would be set to 100 for each NP7 (for a total threshold of 400 for the FortiGate). If npu-dos-meter-mode is set to local, then each NP7 would have a threshold of 400 (for a total threshold of 1600 for a FortiGate with four NP7 processors).

npu-dos-tpe-mode select enable (the default) to insert the dos meter ID into the session table. Select disable if you don't want to insert the DoS meter into the session table. If set to enable, UDP_FLOOD and ICMP_FLOOD DoS protection applies to offloaded sessions. If set to disable, UDP_FLOOD and ICMP_FLOOD DoS protection will not apply to offloaded sessions.

NP7 DoS offloading does not offload processing for all DoS policy anomalies. The following table shows that some anomaly sessions are offloaded to NP7 processors and some are handled by the CPU. In addition, when full-offload is enabled, more types of anomaly processing are handled by NP7 processors than when dos-offload is selected.

NP7 processors offload DoS sessions differently depending on the policy offload level:

DoS policy anomaly	dos-offload selected	full-offload selected
tcp_syn_flood	NP7	NP7
tcp_port_scan	NP7	NP7
tcp_src_session	NP7	NP7
tcp_dst_session	NP7	NP7
udp_flood	NP7	NP7
udp_scan	CPU	NP7
udp_src_session	CPU	NP7
udp_dst_session	CPU	NP7
icmp_flood	NP7	NP7
icmp_sweep	CPU	CPU
icmp_src_session	CPU	CPU
icmp_dst_session	CPU	CPU
ip_src_session	TCP sessions are offloaded to NP7 processors. Other sessions are handled by the CPU.	TCP and UDP sessions are offloaded to NP7 processors. Other sessions are handled by the CPU.
ip_dst_session	TCP sessions are offloaded to NP7 processors. Other sessions are handled by the CPU.	TCP and UDP sessions are offloaded to NP7 processors. Other sessions are handled by the CPU.
sctp_flood	CPU, because the NP7 processor can only send sctp-init packets to MSE	CPU
sctp_scan	CPU	CPU
sctp_src_session	CPU	CPU
sctp_dst_session	CPU	CPU