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Usage
Information
When the configured maximum threshold is exceeded, generation of logs is
stopped. When the interval at which ACL logs are configured 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 configured threshold is exceeded, it is re-enabled for this new interval.
If ACL logging is stopped because the configured threshold is exceeded, it is re-
enabled after the logging interval period elapses. ACL logging is supported for
standard and extended IPv4 ACLs, IPv6 ACLs, and MAC ACLs. You can configure
ACL logging only on ACLs that are applied to ingress interfaces; you cannot enable
logging for ACLs that are associated with egress interfaces.
You can activate flow-based monitoring for a monitoring session by entering the
flow-based enable command in the Monitor Session mode. When you 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
permit – assigns a permit filter for IP packets.
permit icmp (for IPv6 ACLs)
To allow all or specific internet control message protocol (ICMP) messages, configure a filter.
Syntax
permit icmp {source address mask | any | host ipv6-address}
{destination address | any | host ipv6-address} [message-type]
[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 icmp {source address mask | any | host ipv6-
address} {destination address | any | host ipv6-address}
command.
Parameters
log (OPTIONAL) Enter the keyword log to enable the triggering
of ACL log messages.
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Access Control Lists (ACL)