Administrator Guide

If ACL logging is stopped because the configured threshold is exceeded, it is reenabled after the logging interval
period elapses. ACL logging is supported for standard and extended IPv4 ACLs, standard and extended IPv6
ACLs, and standard and extended 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).
seq (for IP ACLs)
Assign a sequence number to a deny or permit filter in an extended IP access list while creating the filter.
Syntax
seq sequence-number {deny | permit} {ip-protocol-number | icmp | ip | tcp |
udp} {source mask | any | host ip-address} {destination mask | any | host ip-
address} [operator port [port]] [ttl operator] [count [byte]] [dscp value]
[order] [fragments] [log [interval minutes] [threshold-in-msgs [count]]
[monitor]
Parameters
ttl Enter the keyword ttl to permit or 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.
• lt (less than) — matches packets that contain a ttl value that is less than the
specified ttl value.
• range(inclusive range of values) — matches packets that contain a ttl value that
falls between the specified range of ttl values.
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 CONFIGURATION-EXTENDED-ACCESS-LIST
Command History
This guide is platform-specific. For command information about other platforms, see the relevant Dell EMC
Networking OS Command Line Reference Guide.
298 Access Control Lists (ACL)