1-45
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring Clientless SSL VPN
Understanding How KCD Works
Requirements
In order for the
kcd-server
command to function, the ASA must establish a trust relationship between
the
source
domain (the domain where the ASA resides) and the
target
or
resource
domain (the domain
where the web services reside). The ASA, using its unique format, crosses the certification path from the
source to the destination domain and acquires the necessary tickets on behalf of the remote access user
to access the services.
This crossing of the certificate path is called cross-realm authentication. During each phase of
cross-realm authentication, the ASA relies on the credentials at a particular domain and the trust
relationship with the subsequent domain.
Understanding How KCD Works
Kerberos relies on a trusted third party to validate the digital identity of entities in a network. These
entities (such as users, host machines, and services running on hosts) are called principals and must be
present in the same domain. Instead of secret keys, Kerberos uses tickets to authenticate a client to a
server. The ticket is derived from the secret key and consists of the client’s identity, an encrypted session
key, and flags. Each ticket is issued by the key distribution center and has a set lifetime.
The Kerberos security system is a network authentication protocol used to authenticate entities (users,
computers, or applications) and protect network transmissions by scrambling the data so that only the
device that the information was intended for can decrypt it. You can configure KCD to provide Clientless
SSL VPN (also known as WebVPN) users with SSO access to any web services protected by Kerberos.
Examples of such web services or applications include Outlook Web Access (OWA), Sharepoint, and
Internet Information Server (IIS).
Two extensions to the Kerberos protocol were implemented:
protocol transition
and
constrained
delegation
. These extensions allow the Clientless or WebVPN remote access users to access Kerberos
authenticated applications in the private network.
The
protocol transition
provides you with increased flexibility and security by supporting different
authentication mechanisms at the user authentication level and by switching to the Kerberos protocol for
security features (such as mutual authentication and constrained delegation) in subsequent application
layers.
Constrained delegation
provides a way for domain administrators to specify and enforce
application trust boundaries by limiting where application services can act on a user’s behalf. This
flexibility improves application security designs by reducing the chance of compromise by an untrusted
service.
For more information on constrained delegation, see RFC 1510 via the IETF website
(
Authentication Flow with KCD
depicts the packet and process flow a user will experience directly and indirectly when
accessing resources trusted for delegation via the clientless portal. This process assumes that the
following tasks have been completed:
•
Configured KCD on ASA
•
Joined the Windows Active Directory and ensured services are trusted for delegation
•
Delegated ASA as a member of the Windows Active Directory domain
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: ......