1-32
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring Inspection of Basic Internet Protocols
PPTP Inspection
hostname(config)# policy-map type inspect netbios netbios_map
hostname(config-pmap)# protocol-violation drop log
hostname(config)# policy-map netbios_policy
hostname(config-pmap)# class inspection_default
hostname(config-pmap-c)# inspect netbios netbios_map
PPTP Inspection
PPTP is a protocol for tunneling PPP traffic. A PPTP session is composed of one TCP channel and
usually two PPTP GRE tunnels. The TCP channel is the control channel used for negotiating and
managing the PPTP GRE tunnels. The GRE tunnels carries PPP sessions between the two hosts.
When enabled, PPTP application inspection inspects PPTP protocol packets and dynamically creates the
GRE connections and xlates necessary to permit PPTP traffic. Only Version 1, as defined in RFC 2637,
is supported.
PAT is only performed for the modified version of GRE
[
RFC 2637
]
when negotiated over the PPTP TCP
control channel. Port Address Translation is
not
performed for the unmodified version of GRE
[
RFC
1701, RFC 1702
]
.
Specifically, the ASA inspects the PPTP version announcements and the outgoing call request/response
sequence. Only PPTP Version 1, as defined in RFC 2637, is inspected. Further inspection on the TCP
control channel is disabled if the version announced by either side is not Version 1. In addition, the
outgoing-call request and reply sequence are tracked. Connections and xlates are dynamic allocated as
necessary to permit subsequent secondary GRE data traffic.
The PPTP inspection engine must be enabled for PPTP traffic to be translated by PAT. Additionally, PAT
is only performed for a modified version of GRE (RFC2637) and only if it is negotiated over the PPTP
TCP control channel. PAT is not performed for the unmodified version of GRE (RFC 1701 and
RFC 1702).
As described in RFC 2637, the PPTP protocol is mainly used for the tunneling of PPP sessions initiated
from a modem bank PAC (PPTP Access Concentrator) to the headend PNS (PPTP Network Server).
When used this way, the PAC is the remote client and the PNS is the server.
However, when used for VPN by Windows, the interaction is inverted. The PNS is a remote single-user
PC that initiates connection to the head-end PAC to gain access to a central network.
SMTP and Extended SMTP Inspection
This section describes the IM inspection engine. This section includes the following topics:
•
SMTP and ESMTP Inspection Overview, page 1-32
•
Configuring an ESMTP Inspection Policy Map for Additional Inspection Control, page 1-34
SMTP and ESMTP Inspection Overview
ESMTP application inspection provides improved protection against SMTP-based attacks by restricting
the types of SMTP commands that can pass through the ASA and by adding monitoring capabilities.
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: ......