Users Guide

Version Description
9.8(2.0) Introduced on the S3100 series.
9.8(1.0) Introduced on the Z9100–ON.
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
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
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.
deny tcp (for Extended IP ACLs)
Configure a filter that drops transmission control protocol (TCP) packets meeting the filter criteria.
Syntax
deny tcp {source mask | any | host ip-address} [bit] [operator port [port]]
{destination mask | any | host ip-address} [ttl operator] [dscp] [bit]
[operator port [port]] [count [byte]] [order] [fragments] [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 deny tcp {source mask | any | host ip-address} {destination mask
| any | host ip-address} command.
Parameters
ttl Enter the keyword ttl to deny a packet based on the time to live value. The range
is from 1 to 255.
operator Enter one of the following logical operand:
● eq(equal to) — matches packets that contain a ttl value that is equal to the
specified ttl value.
● neq(not equal to) — matches packets that contain a ttl value that is not equal
to the specified ttl value.
● gt(greater than) — matches packets that contain a ttl value that is greater
than the specified ttl value.
280 Access Control Lists (ACL)