Service Manual

You can activate ow-based monitoring for a monitoring session by entering the ow-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).
Related Commands
deny — assigns a lter to deny IP trac.
deny udp — assigns a lter to deny UDP trac.
deny udp (for Extended IP ACLs)
To drop user datagram protocol (UDP) packets meeting the lter criteria, congure a lter.
Syntax
deny udp {source mask | any | host ip-address} [operator port [port]]
{destination mask | any | host ip-address} [dscp] [operator port [port]]
[count [byte]] [order] [fragments] [log [interval minutes] [threshold-in-
msgs [count]]
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 deny udp {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 time interval range is from 1 to 10
minutes.
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.
Command Modes CONFIGURATION-EXTENDED-ACCESS-LIST
Command History
Version 9.3(0.0) Added support for logging of ACLs on the S4810, S4820T, and Z9000 platforms.
Usage Information
When the congured maximum threshold is exceeded, generation of logs is stopped. When the interval at
which ACL logs are congured to be recorded expires, the subsequent, fresh interval timer is started and the
packet count for that new interval commences from zero. If ACL logging was stopped previously because
the congured threshold is exceeded, it is re-enabled for this new interval.
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Access Control Lists (ACL)