Configuring MAC Locking
20-46 Security Configuration
Configuring MAC Locking
ThisfeaturelocksaMACaddresstooneormoreports,preventingconnectionofunauthorized
devicesthroughtheport(s).WhensourceMACaddressesarereceivedonspecifiedports,the
switchdiscardsallsubsequentframes notcontainingtheconfiguredsourceaddresses.Theonly
framesforwardedona“locked”portarethosewith
the“locked”MACaddress(es)forthatport.
TherearetwomethodsoflockingaMACtoaport:firstarrivalandstatic.Thefirstarrivalmethod
isdefinedtobelockingthefirstnnumberofMACswhicharriveonaportconfiguredwithMAC
lockingenabled.Thevaluenis
configuredwiththesetmaclockfirstarrivalcommand.
ThestaticmethodisdefinedtobestaticallyprovisioningaMAC‐portlockusingthesetmaclock
command.ThemaximumnumberofstaticMACaddressesallowedforMAClockingonaport
canbeconfiguredwiththesetmaclockstaticcommand.
Youcanconfigure
theswitchtoissueaviolationtrapifapacketarriveswithasourceMAC
addressdifferentfromanyofthecurrentlylockedMACaddressesforthatport.
MACsareunlockedasaresultof:
•Alinkdownevent
•WhenMAClock ingisdisabledonaport
•WhenaMACisaged
outoftheforwardingdatabasewhenFirstArrivalagingisenabled
Whenproperlyconfigured,MAClockingisanexcellentsecuritytoolasitpreventsMACspoofing
onconfiguredports.AlsoifaMACweretobesecuredbysomethinglikeDragonDynamic
IntrusionDetection,MAClockingwouldmakeitmoredifficultfor
ahackertosendpacketsinto
thenetworkbecausethehackerwouldhavetochangetheirMACaddressandmovetoanother
port.Inthemeantimethesystemadministratorwouldbereceivingamaclocktrapnotification.
Purpose
Toreview,disable,enable,andconfigureMAClocking.
Commands
administrative
egress
Port status as assigned by the set vlanauthorization egress command
operational egress If authentication has succeeded, displays the VLAN id assigned for egress.
vlan id If authentication has succeeded, displays the assigned VLAN id for ingress.
Table 20-5 show vlanauthorization Output Details (Continued)
Output What It Displays...
For information about... Refer to page...
show maclock 20-47
show maclock stations 20-48
set maclock enable 20-49
set maclock disable 20-50
set maclock 20-50