C
HAPTER
 24
  |  General Security Measures
Denial of Service Protection
–  933  –
EXAMPLE
Console#show ip arp inspection vlan 1
VLAN ID     DAI Status             ACL Name             ACL Status
--------   ---------------    --------------------    --------------------
1           disabled               sales               static
Console#
DENIAL OF SERVICE PROTECTION
A denial-of-service attack (DoS attack) is an attempt to block the services 
provided by a computer or network resource. This kind of attack tries to 
prevent an Internet site or service from functioning efficiently or at all. In 
general, DoS attacks are implemented by either forcing the target to reset, 
to consume most of its resources so that it can no longer provide its 
intended service, or to obstruct the communication media between the 
intended users and the target so that they can no long communicate 
adequately. 
This section describes commands used to protect against DoS attacks. 
dos-protection
echo-chargen
This command protects against DoS echo/chargen attacks in which the 
echo service repeats anything sent to it, and the chargen (character 
generator) service generates a continuous stream of data. When used 
together, they create an infinite loop and result in a denial-of-service. Use 
the no form to disable this feature.
SYNTAX 
dos-protection echo-chargen [bit-rate-in-kilo rate]
no dos-protection echo-chargen
rate – Maximum allowed rate. (Range: 64-2000 kbits/second)
Table 97: DoS Protection Commands  
Command Function Mode
dos-protection echo-chargen Protects against DoS echo/chargen attacks GC
dos-protection smurf Protects against DoS smurf attacks GC
dos-protection tcp-flooding Protects against DoS TCP-flooding attacks GC
dos-protection tcp-null-scan Protects against DoS TCP-null-scan attacks GC
dos-protection tcp-syn-fin-scan Protects against DoS TCP-SYN/FIN-scan attacks GC
dos-protection tcp-xmas-scan Protects against DoS TCP-XMAS-scan attacks GC
dos-protection udp-flooding Protects against DoS UDP-flooding attacks GC
dos-protection win-nuke Protects against DoS WinNuke attacks GC
show dos-protection Shows the configuration settings for DoS 
protection
PE