Downloads |
Purpose and Scope
Cisco IOS® SSLVPN provides remote secure corporate network (intranet) access over the standard public Internet using a web browser and its native Secure Sockets Layer (SSL) encryption. SSL authentication and encryption/decryption operate at the application level. The end host can be any IP-based host (PC, Mac, Linux/UNIX, etc.) that supports Cisco SSLVPN.
SSLVPN can be used as to provide standalone secure remote access to corporate services. It can also be deployed as a complement to the Cisco Virtual Office solution for mobile users who sometimes need to have access to the corporate intranet from a public Internet access location. Please refer to the Cisco Virtual Office overview (found at http://www.cisco.com/go/cvo) for further information about the solution, its architecture, and all of its components.
This guide describes how to configure and deploy a Cisco IOS Software-based router as an SSLVPN gateway.
Network Architecture
Figure 1 shows an example of how Cisco SSLVPN can be deployed with Cisco Virtual Office.
Figure 1. SSLVPN Topology for an Cisco Virtual Office Deployment
SSLVPN is configured in a Cisco IOS Software-based router.
Using an SSL-enabled web browser, the user establishes a connection to the SSLVPN gateway. Once the user has been authenticated by the authentication, authorization, and accounting (AAA) server, an SSLVPN session is established and the user can access the internal corporate network.
Since the SSLVPN gateway provides an entrance into the corporate network, it should always be installed behind a firewall. Only the SSL port (port 443) should be opened on the corporate firewall for secure access back to the SSLVPN gateway.
Feature Description
Using an SSL-enabled web browser (Internet Explorer, Firefox, or the equivalent), the user can establish a connection to the SSLVPN gateway. The SSLVPN gateway responds to the initial user request with a user logon HTML page. The username and password are submitted to the gateway for authentication with a RADIUS server, and a session is granted only if the authentication is successful.
If a session is established, it is maintained by sending a session cookie to the user browser. This cookie has to be embedded in all subsequent user HTTP requests for authentication at the SSLVPN gateway. If the cookie is missing or incorrect, the session will be dropped, and the user will no longer be able to access the corporate network.
Normally, the session remains until the user logs out, the session times out, or the session is cleared from the SSLVPN gateway.
Cisco IOS SSLVPN delivers full-tunnel SSL VPN access. If a popup blocker is enabled in the user's browser, it is possible that the small SSLVPN toolbar window will not be displayed. To avoid this, disable the popup blocker for this SSLVPN session page.
In a SSLVPN connection, SSL tunnel is used to move data to and from the internal networks at the network (IP) layer. When the user logs into the SSLVPN gateway, the SSL VPN client (AnyConnect) is automatically downloaded and installed on the end user's PC, and the tunnel connection is established. Once the connection is established, the user has full VPN access to the corporate network. Using SSLVPN, it is also possible to have voice support. Using Cisco IP Communicator, the user can register with the Cisco Call Manager in the corporate network and thus have a portable "office phone."
To connect different types of clients (Windows, Mac, Linux), the SSLVPN gateway should have corresponding AnyConnect software installed.
Cisco Secure Desktop is a multifunctional component of the Cisco SSLVPN solution. It does a preconnect assessment to make sure PCs with worms and viruses cannot gain access to the SSLVPN gateway; additionally, Cisco Secure Desktop provides a consistent and reliable means of fully eliminating all traces of sensitive session data by creating a virtual desktop.
Platforms and Images
Supported platforms for Cisco IOS SSLVPN are:
• Cisco 2800 and 3800 Series Integrated Services Routers, and Cisco 7206 Router with Cisco VPN Services Adapter
Cisco IOS SSLVPN is available in image 12.4(15)T and later.
For the latest SSLVPN client package, please visit http://www.cisco.com/pcgi-bin/tablebuild.pl/anyconnect.
For the latest Cisco Secure Desktop package, please visit http://www.cisco.com/pcgi-bin/tablebuild.pl/securedesktop.
Configuration
The following SSLVPN-specific configurations are required on the gateway.
Configuring the Public Key Infrastructure
SSLVPN is based on HTTPS, which requires a public key infrastructure (PKI) trust point to be configured.
One of the first things checked within a certificate is the expiration. A valid date is required, and the router has to have the correct time. To configure the router as a Network Time Protocol (NTP) client, use the following configuration:
ntp server <ntp-server-ip>
The host name and the domain name must be set as well:
hostname sslvpn-gateway
ip domain name cisco.com
After this, RSA keys can be generated:
sslvpn-gateway(config)#crypto key generate rsa general-keys label
sslvpn-certificate modulus 1024
The name for the keys will be: sslvpn-certificate-server.cisco.com
% The key modulus size is 1024 bits
% Generating 1024 bit RSA keys ...[OK]
To configure a trust point and enroll with the certificate server, use the following configuration:
crypto pki trustpoint <trustpoint-name>
enrollment url http://certificate-server
To tell the SSLVPN gateway to use a trust point, use the following configuration:
webvpn gateway <gateway-name>
ssl trustpoint <trustpoint-name>
For more details on certificate management, see Appendix A.
Configuring the User Database
A user database is needed for authenticating the end user with the SSLVPN gateway. The database can be local or any RADIUS/TACACS+ AAA server.
It is best to use a separate AAA server so that unique passwords can be provided for each user, and so that user connections can be logged. This is how the SSLVPN gateway will be configured to use a remote AAA RADIUS server for authentication purposes:
aaa new-model
aaa group server radius sslvpn
server-private <radius-server> auth-port 1812 acct-port 1813 key <radius-key>
aaa authentication login default local group sslvpn
ip http authentication aaa
SSLVPN Configuration
The following sections describe how to enable and configure SSLVPN.
Configuring the Virtual Gateway
Before using the SSLVPN feature, a virtual gateway must be configured and put into service. This specifies the IP address and port to use for SSLVPN and configures the trust point to use. The IP address should be a public IP address configured on an interface or loopback interface on the SSLVPN gateway. The default port is 443. Putting the virtual gateway into service enables SSLVPN service on the gateway.
webvpn gateway sslvpn-gw
ip address 10.10.10.30 port 443
ssl trustpoint SSLVPN
inservice
Configuring the Virtual Context
A SSLVPN virtual context must be configured to associate the virtual SSLVPN gateway with the configured features. Multiple virtual contexts can be configured on the secure gateway, giving access to various features and access modes, depending on the domain configured for each context. Following is an example of configuring a virtual context and putting it into service:
webvpn context sslvpn_context
title "MyCompany SSLVPN Server"
gateway sslvpn-gw domain <domain-name>
inservice
The end user gets access to the different features configured in each context by specifying the domain in the URL when accessing the SSLVPN gateway: https://<SSLVPN-gateway-IP>/<domain-name>. If no domain name is specified in the URL, the default context will be used.
Multiple contexts can be configured, giving different levels of access. For example, two contexts can be configured, one with full-tunnel access and one with Cisco Secure Desktop and full-tunnel access. By going to https://<SSLVPN-gateway>/tunnel, the user will get full-tunnel access to the internal network. Accessing https://<SSLVPN-gateway/csd will give the user access to Cisco Secure Desktop and full-tunnel access.
Configuring the Group Policy
A group policy is configured for each SSLVPN virtual instance. The group policy specifies the SSLVPN features and parameters to be used for this virtual instance. Full-tunnel mode can be enabled or disabled in the group policy, which is then associated with the SSLVPN context.
The following is a configuration example for full-tunnel mode:
webvpn context sslvpn_context
policy group policy-group
functions svc-enabled
svc address-pool "sslvpn-pool"
svc split include 10.0.0.0 255.0.0.0
svc split include 192.168.0.0 255.255.0.0
svc dns-server primary 10.2.2.2
The following associates the group policy with the SSLVPN context:
webvpn context sslvpn_context
default-group-policy policy-group
Configuring the SSLVPN Tunneling Client
To establish an SSLVPN connection, the remote client will download the AnyConnect client package software from the SSLVPN gateway.
Configuration example:
service internal
webvpn install svc flash:sslclient-pkg sequence #
The `sequence #' option is for installing multiple client packages in same gateway.
Example: Anyconnect client packages for Windows, Mac and Linux can be installed in the
Same gateway.
The SSLVPN gateway supplies an IP address to each of the clients logged into the gateway. A local IP address pool must be configured on the gateway, and this pool must be specified in the policy group configuration for the SSLVPN context that allows full-tunnel access.
Configuring the IP address pool:
ip local pool sslvpn-pool 10.1.1.2 10.1.1.62
Full-tunnel mode must be enabled in the SSLVPN context by configuring it in the context's policy group. Split tunneling can also be configured to specify which traffic should be tunneled to the internal network and which traffic should be sent directly to the Internet.
webvpn context sslvpn_context
policy group policy-group
functions svc-required
svc address-pool "sslvpn-pool"
svc split include 10.0.0.0 255.0.0.0
svc split include 192.168.0.0 255.255.0.0
svc dns-server primary 10.2.2.2
When the end user logs into an SSLVPN gateway domain, the AnyConnect client is automatically downloaded and installed on the user's PC. The routing table on the PC is modified to route internal traffic to the internal network and all other traffic directly to the Internet.
Configuring Cisco Secure Desktop
Cisco Secure Desktop eliminates all traces of sensitive data by providing a single, secure location for session activity and removal on the client system. It helps ensure that cookies, browser history, temporary files, and downloaded content are removed from the system after a remote user has logged out or after an SSLVPN session has timed out.
First, the Cisco Secure Desktop package must be installed on the internal flash device on the SSLVPN gateway; then Cisco Secure Desktop can be enabled in the context sub mode.
Installing the Cisco Secure Desktop package:
service internal
webvpn install csd flash: securedesktop-3.0.2.278-K9.pkg
Configuring Cisco Secure Desktop in a context:
webvpn context sslvpn-context
csd enable
Before the client can use Cisco Secure Desktop, the Cisco Secure Desktop Manager must be launched to configure settings for the context in which Cisco Secure Desktop was enabled. This is done by going to https://<gateway-ip>/csd_admin and logging in as "admin" with the enable password configured on the SSLVPN gateway.
Using Cisco Secure Desktop Manager, you can configure the VPN feature policies to use for remote users at different locations. Access can be differentiated based on IP address, certificate, and file and registry information. System detection can also be done before giving the user access to the SSLVPN features.
More details on configuring Cisco Secure Desktop Manager can be found in the Cisco Secure Desktop Configuration Guide http://www.cisco.com/en/US/products/ps6742/tsd_products_support_series_home.html.
When the end user navigates to an SSLVPN gateway domain that has Cisco Secure Desktop enabled, Cisco Secure Desktop is installed on the user's PC. Once the desktop is installed, the user can go to the secure desktop and log in to create an SSLVPN session. The user can also switch between the secure desktop and the guest computer (regular desktop) by clicking in the respective icon/menu option.
Troubleshooting
The following section describes the troubleshooting commands available.
SSLVPN Troubleshooting Commands
Use the following debug commands to help troubleshooting possible problems:
debug webvpn aaa AAA debugs
debug webvpn cookie cookie debugs
debug webvpn count data count code debugs
debug webvpn csd Cisco Secure Desktop debugs
debug webvpn data data code debugs
debug webvpn dns DNS debugs
debug webvpn emweb emweb debugs
debug webvpn emweb state emweb state debugs
debug webvpn http HTTP debugs
debug webvpn package client package debugs
debug webvpn sdps Shim Data Path debugs
debug webvpn sock Socket Layer debugs
debug webvpn sock flow Socket async flow debugs
debug webvpn timer timer code debugs
debug webvpn trie trie code debugs
debug webvpn tunnel tunnel debugs
debug webvpn tunnel detail detailed display of tunnel transactions
debug webvpn tunnel traffic tunnel data packets debugs
debug webvpn url_disp URL disp code debugs
debug webvpn webservice web service debugs
debug webvpn basic debugs
Note: Enabling debug commands affects performance, and enabling multiple debug commands at the same time will make the gateway very slow.
Sessions can be monitored on the SSLVPN gateway using the following show commands:
show webvpn context
sslvpn-gateway#show webvpn context
Codes: AS - Admin Status, OS - Operation Status
VHost - Virtual Host
Context Name Gateway Domain/VHost VRF AS OS
------------ ------- ------------ ------- ---- --------
csd sslvpn-g csd - up up
tunnel sslvpn-g tunnel - up up
show webvpn context <context-name>
sslvpn-gateway#show webvpn context tunnel
Admin Status: up
Operation Status: up
Error and Event Logging: Disabled
CSD Status: Disabled
Certificate authentication type: All attributes (like CRL) are verified
AAA Authentication List not configured
AAA Authorizationtion List not configured
AAA Authentication Domain not configured
Default Group Policy: tunnelpolicy
Associated WebVPN Gateway: webvpn-gw
Domain Name: tunnel
Maximum Users Allowed: 1000 (default)
NAT Address not configured
VRF Name not configured
show webvpn gateway
sslvpn-gateway#show webvpn gateway
Gateway Name Admin Operation
------------ ----- ---------
sslvpn-gw up up
sslvpn-gateway down down
show webvpn gateway <gateway-name>
sslvpn-gateway#show webvpn gateway sslvpn-gw
Admin Status: up
Operation Status: up
IP: 10.10.10.30, port: 443
SSL Trustpoint: SSLVPN
show webvpn install package csd
Displays all the installed csd files
show webvpn install package svc
Displays all the installed svc files
show webvpn install status csd
sslvpn-gateway#show webvpn install status csd
SSLVPN Package Cisco-Secure-Desktop version installed:
CISCO CSD CAT6K
3,1,0,9
Fri 07/22/2005 10:49:35.07 b
show webvpn install status svc
sslvpn-gateway#show webvpn install status svc
SSLVPN Package SSL-VPN-Client version installed:
CISCO STC win2k+ 1.0.0
1,0,2,127
Fri 07/22/2005 12:14:45.43 D
show webvpn nbns context all
sslvpn-gateway#show webvpn nbns context all
NetBIOS name IP Address Timestamp
0 total entries
NetBIOS name IP Address Timestamp
0 total entries
NetBIOS name IP Address Timestamp
0 total entries
show webvpn policy group <policy-name> context all
sslvpn-gateway#show webvpn policy group csdpolicy context all
WEBVPN: group policy = csdpolicy ; context = csd
idle timeout = 2100 sec
session timeout = 43200 sec
address pool name = "sslvpn-pool"
dpd client timeout = 300 sec
dpd gateway timeout = 300 sec
split include = 10.0.0.0 255.0.0.0
split include = 192.168.0.0 255.255.0.0
DNS primary server = <dns-server>
show webvpn session context <context-name>
Shows current session information for a specific context.
show webvpn session context all
Shows current session information for all contexts
show webvpn session user <username>
Shows current session information for a specified user
show webvpn stats context <context-name>
Shows all statistics for an SSLVPN context
show webvpn stats detail
Shows detailed SSLVPN statistics
show webvpn stats socket
Shows SSLVPN socket statistics
show webvpn stats tunnel
Shows SSLVPN tunnel statistics
Clear commands are available that will clear the NetBIOS Name Service (NBNS) cache, clear the SSLVPN sessions, and clear the statistics:
clear webvpn session
clear webvpn stats
Appendix A: Full Configuration for SSLVPN
The following shows a full SSLVPN configuration.
hostname sslvpn-gateway
!
aaa new-model
!
aaa group server radius ssl-users
server-private <server ip> auth-port 1812 acct-port 1813 key <aaa-key>
!
aaa authentication login default local group ssl-users
!
aaa session-id common
!
clock timezone PST -8
clock summer-time PDT recurring
ip subnet-zero
ip cef
!
ip domain name cisco.com
ip host sslvpn-gateway.cisco.com <server ip>
ip name-server <server ip>
!
crypto pki trustpoint SSLVPN
enrollment url http://ca-server:80
serial-number none
fqdn sslvpn-gateway.cisco.com
ip-address none
subject-name CN=sslvnp-gateway.cisco.com
revocation-check crl
!
crypto pki certificate chain SSLVPN
certificate <removed>
certificate ca <removed>
!
interface GigabitEthernet0/0
ip address 10.10.10.30 255.255.255.240
duplex full
speed 100
media-type rj45
negotiation auto
!
!
ip classless
ip local pool sslvpn-pool 10.10.10.50 10.10.10.100
ip route 0.0.0.0 0.0.0.0 10.10.10.40
!
!
no ip http server
no ip http secure-server
ip http authentication aaa
!
!
line con 0
exec-timeout 300 0
stopbits 1
line aux 0
stopbits 1
line vty 0 4
session-timeout 15
exec-timeout 300 0
password <password>
transport input ssh
!
scheduler allocate 20000 1000
ntp clock-period 17179207
ntp server <ntp-server-ip>
!
webvpn gateway sslvpn-gw
ip address 10.10.10.30 port 443
ssl trustpoint SSLVPN
inservice
!
webvpn install svc flash:/webvpn/svc.pkg sequence 1
!
webvpn install csd flash:/webvpn/sdesktop.pkg
webvpn context tunnel
title "Welcome to SSLVPN : unauthorized access is prohibited"
title-color #336699
ssl authenticate verify all
!
!
policy group tunnelpolicy
functions svc-required
timeout idle 3555
timeout session 1209555
svc address-pool "sslvpn-pool"
svc keep-client-installed
svc split include 128.10.0.0 255.255.0.0
svc split include 144.254.0.0 255.255.0.0
svc dns-server primary 171.68.226.120
svc wins-server primary 171.69.2.87
svc wins-server secondary 171.68.235.228
default-group-policy tunnelpolicy
gateway webvpn-gw domain tunnel
inservice
!
webvpn context csd
ssl encryption
ssl authenticate verify all
!
!