Administrator Guide

enable this capability, traffic with particular flows 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 specified traffic instead all traffic on the interface.
This feature is particularly useful when looking for malicious traffic. It is available for
Layer 2 and Layer 3 ingress and egress traffic. You may specify traffic 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
ip access-list extended — creates an extended ACL.
permit tcp — assigns a permit filter for TCP packets.
permit udp — assigns a permit filter for UDP packets.
permit (for Standard MAC ACLs)
To forward packets from a specific source MAC address, configure a filter.
Syntax
permit {any | mac-source-address [mac-source-address-mask]}
[count [byte]] | [log [interval minutes] [threshold-in-msgs
[count]] [monitor]
To remove this filter, you have two choices:
• Use the no seq sequence-number command if you know the filter’s
sequence number.
• Use the no permit {any | mac-source-address mac-source-
address-mask
} 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 traffic that you want to monitor and the ACL
in which you are creating the rule is applied to the monitored
interface.
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Access Control Lists (ACL)