Cisco Systems ASA 5585-X Manual De Usuario

Basic threat detection statistics include activity that might be related to an attack, such as a DoS attack.

This section includes the following topics:

Using basic threat detection statistics, the ASA monitors the rate of dropped packets and security events 
due to the following reasons:

Denial by ACLs

Bad packet format (such as invalid-ip-header or invalid-tcp-hdr-length)

Connection limits exceeded (both system-wide resource limits, and limits set in the configuration)

DoS attack detected (such as an invalid SPI, Stateful Firewall check failure)

Basic firewall checks failed (This option is a combined rate that includes all firewall-related packet 
drops in this bulleted list. It does not include non-firewall-related drops such as interface overload, 
packets failed at application inspection, and scanning attack detected.)

Suspicious ICMP packets detected

Packets failed application inspection

Interface overload

Scanning attack detected (This option monitors scanning attacks; for example, the first TCP packet 
is not a SYN packet, or the TCP connection failed the 3-way handshake. Full scanning threat 
detection (see the 

) takes this 

scanning attack rate information and acts on it by classifying hosts as attackers and automatically 
shunning them, for example.)

Incomplete session detection such as TCP SYN attack detected or no data UDP session attack 
detected

When the ASA detects a threat, it immediately sends a system log message (733100). The ASA tracks 
two types of rates: the average event rate over an interval, and the burst event rate over a shorter burst 
interval. The burst rate interval is 1/30th of the average rate interval or 10 seconds, whichever is higher. 

All models

Base License.