Administrator Guide

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
• deny — configure a filter to drop packets.
• permit — configure a filter to forward packets.
seq (for IPv6 ACLs)
Assign a sequence number to a deny or permit the filter in an IPv6 access list while creating the filter.
Syntax
seq sequence-number {deny | permit} {ipv6-protocol-number | icmp | ip | tcp |
udp} {source address mask | any | host ipv6-address} {destination address | any
| host ipv6-address} [operator port [portnumber ]] [count [byte]] [log
[interval minutes] [threshold-in-msgs [count]] [monitor]
To delete a filter, use the no seq sequence-number command.
Parameters
sequence-number Enter a number from 0 to 4294967290.
deny Enter the keyword deny to configure a filter to drop packets meeting this condition.
permit Enter the keyword permit to configure a filter to forward packets meeting this criteria.
ipv6-protocol-
number
Enter a number to filter based on the protocol identified in the IPv6 protocol header.
icmp Enter the keyword icmp to configure an ICMP access list filter.
ip Enter the keyword ip to configure a generic IP access list. The keyword ip specifies that
the access list permits all IP protocols.
tcp Enter the keyword tcp to configure a TCP access list filter.
udp Enter the keyword udp to configure a UDP access list filter.
source Enter an IP address in dotted decimal format of the network from which the packet was
received.
mask (OPTIONAL) Enter a network mask in /prefix format (/x) .
any Enter the keyword any to specify that all routes are subject to the filter.
host ipv6-address Enter the keyword host and then enter the IPv6 address to specify a host IP address or
hostname.
operator (OPTIONAL) Enter one of the following logical operands:
• eq = equal to
• neq = not equal to
• gt = greater than
• lt = less than
288 Access Control Lists (ACL)