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Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring Management Access
Configuring ICMP Access
Configuring ICMP Access
By default, you can send ICMP packets to any ASA interface using either IPv4 or IPv6. This section tells
how to limit ICMP management access to the ASA. You can protect the ASA from attacks by limiting
the addresses of hosts and networks that are allowed to have ICMP access to the ASA.
Note
For allowing ICMP traffic through the ASA, see
Chapter 1, “Configuring Access Rules.”
This section includes the following topics:
•
Information About ICMP Access, page 1-10
•
Licensing Requirements for ICMP Access, page 1-10
•
Guidelines and Limitations, page 1-11
•
•
Configuring ICMP Access, page 1-12
Information About ICMP Access
ICMP in IPv6 functions the same as ICMP in IPv4. ICMPv6 generates error messages, such as ICMP
destination unreachable messages and informational messages like ICMP echo request and reply
messages. Additionally ICMP packets in IPv6 are used in the IPv6 neighbor discovery process and path
MTU discovery.
We recommend that you always grant permission for the ICMP unreachable message type (type 3).
Denying ICMP unreachable messages disables ICMP path MTU discovery, which can halt IPsec and
PPTP traffic. See RFC 1195 and RFC 1435 for details about path MTU discovery.
If you configure ICMP rules, then the ASA uses a first match to the ICMP traffic followed by an implicit
deny all entry. That is, if the first matched entry is a permit entry, the ICMP packet continues to be
processed. If the first matched entry is a deny entry or an entry is not matched, the ASA discards the
ICMP packet and generates a syslog message. An exception is when an ICMP rule is not configured; in
that case, a permit statement is assumed.
Licensing Requirements for ICMP Access
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Model
License Requirement
All models
Base License.
Summary of Contents for 5505 - ASA Firewall Edition Bundle
Page 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Page 61: ...P A R T 1 Getting Started with the ASA ...
Page 62: ......
Page 219: ...P A R T 2 Configuring High Availability and Scalability ...
Page 220: ......
Page 403: ...P A R T 2 Configuring Interfaces ...
Page 404: ......
Page 499: ...P A R T 2 Configuring Basic Settings ...
Page 500: ......
Page 533: ...P A R T 2 Configuring Objects and Access Lists ...
Page 534: ......
Page 601: ...P A R T 2 Configuring IP Routing ...
Page 602: ......
Page 745: ...P A R T 2 Configuring Network Address Translation ...
Page 746: ......
Page 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
Page 846: ......
Page 981: ...P A R T 2 Configuring Access Control ...
Page 982: ......
Page 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
Page 1062: ......
Page 1093: ...P A R T 2 Configuring Application Inspection ...
Page 1094: ......
Page 1191: ...P A R T 2 Configuring Unified Communications ...
Page 1192: ......
Page 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
Page 1334: ......
Page 1379: ...P A R T 2 Configuring Advanced Network Protection ...
Page 1380: ......
Page 1475: ...P A R T 2 Configuring Modules ...
Page 1476: ......
Page 1549: ...P A R T 2 Configuring VPN ...
Page 1550: ......
Page 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
Page 1966: ......
Page 2059: ...P A R T 2 System Administration ...
Page 2060: ......
Page 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Page 2099: ...P A R T 2 Reference ...
Page 2100: ......