1-4
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring the Botnet Traffic Filter
Information About the Botnet Traffic Filter
When you add a domain name to the static database, the ASA waits 1 minute, and then sends a DNS
request for that domain name and adds the domain name/IP address pairing to the
DNS host cache
. (This
action is a background process, and does not affect your ability to continue configuring the ASA). We
recommend also enabling DNS packet inspection with Botnet Traffic Filter snooping. The ASA uses
Botnet Traffic Filter snooping instead of the regular DNS lookup to resolve static blacklist domain names
in the following circumstances:
•
The ASA DNS server is unavailable.
•
A connection is initiated during the 1 minute waiting period before the ASA sends the regular DNS
request.
If DNS snooping is used, when an infected host sends a DNS request for a name on the static database,
the ASA looks inside the DNS packets for the domain name and associated IP address and adds the name
and IP address to the DNS reverse lookup cache.
If you do not enable Botnet Traffic Filter snooping, and one of the above circumstances occurs, then that
traffic will not be monitored by the Botnet Traffic Filter.
Information About the DNS Reverse Lookup Cache and DNS Host Cache
When you use the dynamic database with DNS snooping, entries are added to the DNS reverse lookup
cache. If you use the static database, entries are added to the DNS host cache (see the
About the Static Database” section on page 1-3
about using the static database with DNS snooping and
the DNS reverse lookup cache).
Entries in the DNS reverse lookup cache and the DNS host cache have a time to live (TTL) value
provided by the DNS server. The largest TTL value allowed is 1 day (24 hours); if the DNS server
provides a larger TTL, it is truncated to 1 day maximum.
For the DNS reverse lookup cache, after an entry times out, the ASA renews the entry when an infected
host initiates a connection to a known address, and DNS snooping occurs.
For the DNS host cache, after an entry times out, the ASA periodically requests a refresh for the entry.
For the DNS host cache, the maximum number of blacklist entries and whitelist entries is 1000 each.
lists the maximum number of entries in the DNS reverse lookup cache per model.
Table 1-1
DNS Reverse Lookup Cache Entries per Model
ASA Model
Maximum Entries
ASA 5505
5000
ASA 5510
10,000
ASA 5520
20,000
ASA 5540
40,000
ASA 5550
40,000
ASA 5580
100,000
Содержание 5505 - ASA Firewall Edition Bundle
Страница 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Страница 61: ...P A R T 1 Getting Started with the ASA ...
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Страница 218: ...1 56 Cisco ASA Series CLI Configuration Guide Chapter 1 Managing Feature Licenses Feature History for Licensing ...
Страница 219: ...P A R T 2 Configuring High Availability and Scalability ...
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Страница 358: ...1 22 Cisco ASA Series CLI Configuration Guide Chapter 1 Information About Failover Failover Messages ...
Страница 403: ...P A R T 2 Configuring Interfaces ...
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Страница 499: ...P A R T 2 Configuring Basic Settings ...
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Страница 516: ...1 16 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Basic Settings Monitoring DNS Cache ...
Страница 533: ...P A R T 2 Configuring Objects and Access Lists ...
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Страница 558: ...1 4 Cisco ASA Series CLI Configuration Guide Chapter 1 Information About Access Lists Where to Go Next ...
Страница 601: ...P A R T 2 Configuring IP Routing ...
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Страница 632: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Defining Route Maps Feature History for Route Maps ...
Страница 680: ...1 48 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring OSPF Feature History for OSPF ...
Страница 745: ...P A R T 2 Configuring Network Address Translation ...
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Страница 844: ...1 32 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Twice NAT Feature History for Twice NAT ...
Страница 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
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Страница 859: ...1 13 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring AAA Servers and the Local Database Configuring AAA ...
Страница 871: ...1 25 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring AAA Servers and the Local Database Configuring AAA ...
Страница 981: ...P A R T 2 Configuring Access Control ...
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Страница 994: ...1 12 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Access Rules Feature History for Access Rules ...
Страница 1028: ...1 34 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Management Access Feature History for Management Access ...
Страница 1054: ...1 26 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring AAA Rules for Network Access Feature History for AAA Rules ...
Страница 1060: ...1 6 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Web Cache Services Using WCCP Feature History for WCCP ...
Страница 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
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Страница 1093: ...P A R T 2 Configuring Application Inspection ...
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Страница 1191: ...P A R T 2 Configuring Unified Communications ...
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Страница 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
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Страница 1379: ...P A R T 2 Configuring Advanced Network Protection ...
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Страница 1448: ...1 20 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Threat Detection Configuration Examples for Threat Detection ...
Страница 1474: ...1 18 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Filtering Services Monitoring Filtering Statistics ...
Страница 1475: ...P A R T 2 Configuring Modules ...
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Страница 1504: ...1 28 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring the ASA IPS Module Feature History for the ASA IPS module ...
Страница 1528: ...1 24 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring the ASA CX Module Feature History for the ASA CX Module ...
Страница 1548: ...1 20 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring the ASA CSC Module Feature History for the CSC SSM ...
Страница 1549: ...P A R T 2 Configuring VPN ...
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Страница 1592: ...1 42 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring IPsec and ISAKMP Supporting the Nokia VPN Client ...
Страница 1612: ...1 20 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring L2TP over IPsec Feature History for L2TP over IPsec ...
Страница 1796: ...1 6 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring the PPPoE Client Using Related Commands ...
Страница 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
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Страница 1988: ...1 22 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring Logging Feature History for Logging ...
Страница 2002: ...1 14 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring NetFlow Secure Event Logging NSEL Feature History for NSEL ...
Страница 2036: ...1 34 Cisco ASA Series CLI Configuration Guide Chapter 1 Configuring SNMP Feature History for SNMP ...
Страница 2059: ...P A R T 2 System Administration ...
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Страница 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Страница 2099: ...P A R T 2 Reference ...
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