Users Guide

egress direction. Flow-based monitoring conserves bandwidth by monitoring only specied trac instead all trac
on the interface. This feature is particularly useful when looking for malicious trac. It is available for Layer 2 and
Layer 3 ingress and egress trac. You may specify trac 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).
deny icmp (for Extended IPv6 ACLs)
Congure a lter to drop all or specic ICMP messages.
NOTE: Only the options that have been newly introduced in Release 9.3(0.0) and Release 9.4(0.0) are described here. For a
complete description on all of the keywords and variables that are available with this command, refer the topic of this command
discussed earlier in this guide.
Syntax
deny icmp {source address mask | any | host ipv6-address} {destination address
| any | host ipv6-address} [message-type] [ttl operator] [count [byte]] | [log
[interval minutes] [threshold-in-msgs [count]] [monitor]
To remove this lter, you have two choices:
• Use the no seq sequence-number command syntax if you know the lter’s sequence number
•
Use the no deny icmp {source address mask | any | host ipv6-address}
{destination address | any | host ipv6-address} command
Parameters
source address
mask
Enter a network mask in /prex format (/x) or A.B.C.D. The mask, when specied 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 lter.
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.
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 specied
ttl value.
• neq(not equal to) — matches packets that contain a ttl value that is not equal to the
specied ttl value.
•
gt(greater than) — matches packets that contain a ttl value that is greater than the
specied ttl value.
• lt (less than) — matches packets that contain a ttl value that is less than the
specied ttl value.
• range(inclusive range of values) — matches packets that contain a ttl value that
falls between the specied 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. You can enter a
threshold in the range of 1-100.
Access Control Lists (ACL) 359