Allied Telesis AT-S63 - Manual (Page 664)

Chapter 31: Denial of Service Defense
664 Section IV: Security
IP Options
Attack
In the basic scenario of an IP attack, an attacker sends packets containing
bad IP options. There are several types of IP option attacks and the
AT-S63 management software does not distinguish between them.
Rather, the defense mechanism counts the number of ingress IP packets
containing IP options received on a port. If the number exceeds 20
packets per second, the switch considers this a possible IP options attack
and does the following occurs:
❑ It sends an SNMP trap to the management stations.
❑ The switch port discards all ingress packets containing IP options
for one minute.
This defense mechanism does not involve the switch’s CPU. You can
activate it on as many ports as you want without it impacting switch
performance.
Note
This defense does not actually check IP packets for bad IP options; it
can only alert you to a possible attack.
Denial of
Service Defense
Guidelines
Below are guidelines to observe when using this feature:
❑ A switch port can support more than one DoS defense at a time.
❑ The Teardrop and the Ping of Death defenses are CPU intensive.
Use these defenses with caution.
❑ Some defenses allow you to specify a mirror port where offending
traffic is copied.