
C-30
Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 5.0
78-16527-01
Appendix C Troubleshooting
Troubleshooting the 4200 Series Appliance
sensor(config)#
service signature-definition sig0
sensor(config-sig)#
signatures 1000 0
sensor(config-sig-sig)#
engine atomic-ip
sensor(config-sig-sig-ato)#
event-action reset-tcp-connection|produc-alert
sensor(config-sig-sig-ato)#
show settings
atomic-ip
-----------------------------------------------
event-action: produce-alert|reset-tcp-connection default: produce-alert
fragment-status: any <defaulted>
specify-l4-protocol
-----------------------------------------------
no
-----------------------------------------------
-----------------------------------------------
-----------------------------------------------
specify-ip-payload-length
-----------------------------------------------
no
-----------------------------------------------
-----------------------------------------------
-----------------------------------------------
specify-ip-header-length
-----------------------------------------------
no
-----------------------------------------------
-----------------------------------------------
-----------------------------------------------
specify-ip-tos
-----------------------------------------------
--MORE--
Step 3
Exit signature definition submode:
sensor(config-sig-sig-ato)#
exit
sensor(config-sig-sig)#
exit
sensor(config-sig)#
exit
Apply Changes:?[yes]:
Step 4
Press
Enter
to apply the changes or type
no
to discard them.
Step 5
Make sure the correct alarms are being generated:
sensor#
show events alert
evAlert: eventId=1047575239898467370 severity=medium
originator:
hostId: sj_4250_40
appName: sensorApp
appInstanceId: 1004
signature: sigId=20000 sigName=STRING.TCP subSigId=0 version=Unknown
addr: locality=OUT 172.16.171.19
port: 32771
victim:
addr: locality=OUT 172.16.171.13 port: 23
actions:
tcpResetSent: true
Step 6
Make sure the switch is allowing incoming TCP reset packet from the sensor.
Refer to your switch documentation for the procedure.
Step 7
Make sure the resets are being sent:
root#
./tcpdump -i eth0 src host 172.16.171.19
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: listening on eth0