Users Guide

You can activate ow-based monitoring for a monitoring session by entering the flow-based enable
command in the Monitor Session mode. When you enable this capability, trac with particular ows that are
traversing through the ingress and egress interfaces are examined and, appropriate ACLs can be applied in
both the ingress and egress direction. Flow-based monitoring conserves bandwidth by monitoring only
specied trac instead all trac on the interface. This feature is particularly useful when looking for
malicious trac. It is available for Layer 2 and Layer 3 ingress and egress trac. You may specify trac using
standard or extended access-lists. This mechanism copies all incoming or outgoing packets on one port and
forwards (mirrors) them to another port. The source port is the monitored port (MD) and the destination
port is the monitoring port (MG).
permit icmp (for Extended IP ACLs)
Congure a lter to allow all or specic ICMP messages.
Syntax
permit icmp {source mask | any | host ip-address} {destination mask | any |
host ip-address} [dscp] [message-type] [count [byte]] [order] [fragments]
[log [interval minutes] [threshold-in-msgs [count]] [monitor]
To remove this lter, you have two choices:
• Use the no seq sequence-number command if you know the lter’s sequence number.
•
Use the no permit icmp {source mask | any | host ip-address} {destination
mask | any | host ip-address} command.
Parameters
log (OPTIONAL) Enter the keyword log to enable the triggering of ACL log messages.
threshold-in msgs
count
(OPTIONAL) Enter the threshold-in-msgs keyword followed by a value to
indicate the maximum number of ACL logs that can be generated, exceeding which
the generation of ACL logs is terminated with the seq, permit, or deny
commands. The threshold range is from 1 to 100.
interval minutes (OPTIONAL) Enter the keyword interval followed by the time period in minutes
at which ACL logs must be generated. The interval range is from 1 to 10 minutes.
monitor (OPTIONAL) Enter the keyword monitor when the rule is describing the trac
that you want to monitor and the ACL in which you are creating the rule is applied
to the monitored interface.
Defaults
By default, 10 ACL logs are generated if you do not specify the threshold explicitly.
The default frequency at which ACL logs are generated is ve minutes. By default, ow-based monitoring is
not enabled.
Command Modes CONFIGURATION-STANDARD-ACCESS-LIST
Command History
Version Description
9.7(0.0) Introduced on the S6000–ON.
9.4(0.0) Added support for ow-based monitoring on the S4810, S4820T, S6000, and
Z9000 platforms.
9.3(0.0) Added support for logging of ACLs on the S4810, S4820T, and Z9000 platforms.
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Access Control Lists (ACL)