CLI Guide

deny icmp
To drop all or specific internet control message protocol (ICMP) messages, configure a filter.
Syntax
deny icmp {source mask | any | host ip-address} {destination mask | any
| host ip-address} [type] [ttl operator] [dscp] [count [byte] [order]
[fragments] [monitor] [no-drop]
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 icmp {source mask | any | host ip-address} {destination
mask | any | host ip-address} command.
Parameters
source Enter the IP address of the network or host from which the packets were sent.
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-address Enter the keyword host then the IP 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
For IPv6:
echo count
echo-reply count
nd-ns count
nd-na count
packet-too-big count
parameter-problem count
time-exceeded count
port-unreachable count
The ICMP packets cannot be filtered using mirroring ACL.
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.
Access Control Lists (ACL) 195