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
•
— configure a filter to drop packets.
•
— configure a filter to forward 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
} [
type
] [
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
source address
mask
Enter a network mask in /prefix format (/x) or A.B.C.D. The mask, when specified in
A.B.C.D format, may be either contiguous or non-contiguous.
any
Enter the keyword
any
to specify that all routes are subject to the filter.
host
ip-v6address
Enter the keyword
host
then the IPv6 address to specify a host IP address.
destination
Enter the IP address of the network or host to which the packets are sent.
type
Enter the ICMP packet type. The following types are available:
For IPv4:
echo count
echo-reply count
host-unreachable count
host-unknown count
network-unknown count
net-unreachable count
packet-too-big count
parameter-problem count
port-unreachable count
source-quench count
time-exceeded count
Access Control Lists (ACL)
313
