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Firewall Interface Commands
16-132 Configuring Security
no ip firewall ip-options {loose-source-route | strict-source-route | record-
route | time-stamp | other | all} {in | out | both}
Default
IPoptionsarenotallowedinboundandoutbound.
Mode
Interfaceconfiguration:XSR(config-if<xx>)#
Example
ThefollowingexamplesetsloosesourceroutingonbothincomingandoutgoingpacketsatF2:
XSR(config-if<F2>)#ip firewall ip-op loose-source-route both
ip firewall sync-attack-protect
TheSYNCattackmonitor/blockerisolatesahostthatgeneratesafloodofSYNCpacketstothe
XSR’sfirewallandblockstrafficfromthatspecifichost,whileallowingdatapacketstopass.
Syntax
ip firewall sync-attack-protect {block-host | check-host | sync-queue} threshold
[threshold]
Syntax of the “no” Form
Thenoformofthiscommanddisablesthefunction:
no ip firewall sync-attack-protect {block-host | check-host | sync-queue}
threshold
Mode
Interfaceconfiguration:XSR(config-if<xx>)#
block-host
Blockhostwhensyncpacketrateexceedsthisvalue(syncpackets/sec).The
XSRcanblockupto20hostsatanygiventime.Whenblocked,allsyncpackets
toandframeshostaredropped,whileotherpacketsareallowedtogo
through.XSRautomaticallyunblockhostwhenthesyncpacketrate
ofthehost
dropstozerofor25seconds.
Thresholdrangeis10‐5,000,defaultis100
check-host
StartstomonitorsyncpacketrateofeachhostofaClassCsubnetifthesync
packetrateofthesubnetexceedsthisvalue.TheXSRcanmonitorupto3,000
classCsubnets.
Thresholdrangeis10‐5,000,defaultis100
sync-queue
Initiatessyncattackprotectionwhensyncbacklogqueueexceedsthisvalue.
Rangeis50to5,000,defaultis500.
threshold
Thelimitinwhichtheaboveparametersareenabled.