1-21
Cisco ASA Series CLI Configuration Guide
Chapter 1 Information About NAT
Routing NAT Packets
Figure 1-14
Proxy ARP Problems with Identity NAT
In rare cases, you need proxy ARP for identity NAT; for example for virtual Telnet. When using
AAA for network access, a host needs to authenticate with the ASA using a service like Telnet
before any other traffic can pass. You can configure a virtual Telnet server on the ASA to provide
the necessary login. When accessing the virtual Telnet address from the outside, you must configure
an identity NAT rule for the address specifically for the proxy ARP functionality. Due to internal
processes for virtual Telnet, proxy ARP lets the ASA keep traffic destined for the virtual Telnet
address rather than send the traffic out the source interface according to the NAT rule. (See
Figure 1-15
Proxy ARP and Virtual Telnet
Transparent Mode Routing Requirements for Remote Networks
When you use NAT in transparent mode,some types of traffic require static routes. See the
“MAC
Address vs. Route Lookups” section on page 4-5
for more information.
209.165.200.225
209.165.200.230
209.165.200.231
Identity NAT for
“any” with Proxy ARP
Outside
Inside
1
2
4
ARP for 209.165.200.230.
Traffic incorrectly sent to ASA.
Proxy ARP for 209.165.200.230.
3
ARP Response
Too late
209.165.201.11
Virtual Telnet:
209.165.200.230
Identity NAT for
209.165.200.230
between inside and outside
with Proxy ARP
Outside
Inside
Server
1
2
3
Telnet to 209.165.200.230.
Communicate with server.
Authenticate.
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: ......