Administrator Guide

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 – configures a filter to forward packets.
permit udp (for IPv6 ACLs)
Configure a filter to pass UDP packets meeting the filter criteria.
Syntax
permit udp {source address mask | any | host ipv6-address} [operator port
[port]] {destination address | any | host ipv6-address} [operator port
[port]] [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 udp {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.
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.
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 five minutes. By default, flow-based monitoring
is not enabled.
Command Modes ACCESS-LIST
Command
History
Version Description
9.7(0.0) Introduced on the S6000–ON.
9.4(0.0) Added support for flow-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.
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
240 Access Control Lists (ACL)