- Finding Feature Information
- Contents
- Prerequisites for HTTPS—HTTP Server and Client with SSL 3.0
- Restrictions for HTTPS—HTTP Server and Client with SSL 3.0
- Information About HTTPS—HTTP Server and Client with SSL 3.0
- How to Configure the HTTPS—HTTP Server and Client with SSL 3.0
HTTPS—HTTP Server and Client with SSL 3.0
The HTTPS—HTTP Server and Client with SSL 3.0 feature provides Secure Socket Layer (SSL) version 3.0 support for the HTTP 1.1 server and HTTP 1.1 client within Cisco IOS software. SSL provides server authentication, encryption, and message integrity to allow secure HTTP communications. SSL also provides HTTP client authentication. HTTP over SSL is abbreviated as HTTPS.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for HTTPS—HTTP Server and Client with SSL 3.0" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•Prerequisites for HTTPS—HTTP Server and Client with SSL 3.0
•Restrictions for HTTPS—HTTP Server and Client with SSL 3.0
•Information About HTTPS—HTTP Server and Client with SSL 3.0
•How to Configure the HTTPS—HTTP Server and Client with SSL 3.0
•Configuration Examples for the HTTPS—HTTP Server and Client with SSL 3.0 feature
•Feature Information for HTTPS—HTTP Server and Client with SSL 3.0
Prerequisites for HTTPS—HTTP Server and Client with SSL 3.0
To enable secure HTTP connections (encryption) without a configured certificate authority trustpoint, you must first ensure that each device has the key (such as a Rivest, Shamir, and Adleman [RSA] public key or a shared key) of the other device. In most cases, an RSA key pair will be generated automatically. The RSA key pair is used for creating a self-signed certificate (which is also generated automatically).
Restrictions for HTTPS—HTTP Server and Client with SSL 3.0
The HTTPS—HTTP Server and Client with SSL 3.0 feature is available only in Cisco IOS software images that support SSL. SSL is supported in "IPSec 56" (contains "k8" in the image name) and "IPSec 3DES" images (contains "k9" in the image name). "IPSec 56" images provide up to 64-bit encryption, "IPSec 3 DES" images provide greater than 64-bit encryption. The following CipherSuites are supported in IPSec Data Encryption Standard (DES) images:
•SSL_RSA_WITH_RC4_128_MD5—RSA key exchange (RSA Public Key Cryptography) with RC4 128-bit encryption and message digest algorithm 5 (MD5) for message digest
•SSL_RSA_WITH_RC4_128_SHA—RSA key exchange with RC4 128-bit encryption and Secure Hash Algorithm (SHA) for message digest
•SSL_RSA_WITH_3DES_EDE_CBC_SHA—RSA key exchange with 3DES and DES-EDE3-CBC for message encryption and SHA for message digest
•SSL_RSA_WITH_DES_CBC_SHA—RSA key exchange with DES-CBC for message encryption and SHA for message digest
For IPSec 56 images, only the SSL_RSA_WITH_DES_CBC_SHA CipherSuite is supported. For further details on these CipherSuites, see the SSL Protocol Version 3.0 Internet-Draft document (see the "Additional References" section).
RSA (in conjunction with the specified encryption and digest algorithm combinations) is used for both key generation and authentication on SSL connections. This usage is independent of whether a certificate authority (CA) trustpoint is configured.
Information About HTTPS—HTTP Server and Client with SSL 3.0
To configure the HTTP with SSL 3.0 (HTTPS) feature, you should understand the following concepts:
•Secure HTTP Server and Secure HTTP Client
•Certificate Authority Trustpoints
Secure HTTP Server and Secure HTTP Client
A secure HTTP connection means that data sent to and received from an HTTP server are encrypted before being sent out over the Internet. HTTP with SSL encryption provides a secure connection to allow such functions as configuring a router from a web browser. Cisco's implementation of the secure HTTP server and secure HTTP client uses an implementation of the SSL version 3.0. Application layer encryption provides an alternative to older methods such as having to set up a tunnel to the HTTP server for remote management. HTTP over SSL is abbreviated as HTTPS; the URL of a secure connection will begin with https:// instead of http://.
The Cisco IOS HTTP secure server's primary role is to listen for HTTPS requests on a designated port (the default HTTPS port is 443) and to pass the request to the HTTP 1.1 web server. The HTTP 1.1 server processes requests and passes responses (served pages) back to the HTTP secure server, which, in turn, responds to the original request.
The Cisco IOS HTTP secure client's primary role is to respond to Cisco IOS application requests for HTTPS User Agent services, perform HTTPS User Agent services on the application's behalf, and pass the response back to the application.
Certificate Authority Trustpoints
Certificate authorities (CAs) are responsible for managing certificate requests and issuing certificates to participating IPSec network devices. These services provide centralized security key and certificate management for the participating devices. Specific CA servers are referred to as "trustpoints."
The HTTPS server provides a secure connection by providing a certified X.509v3 certificate to the client when a connection attempt is made. The certified X.509v3 certificate is obtained from a specified CA trustpoint. The client (usually a web browser), in turn, has a public key that allows it to authenticate the certificate.
Configuring a CA trustpoint is highly recommended for secure HTTP connections. However, if a CA trustpoint is not configured for the routing device running the HTTPS server, the server will certify itself and generate the needed RSA key pair. Because a self-certified (self-signed) certificate does not provide adequate security, the connecting client will generate a notification that the certificate is self-certified, and the user will have the opportunity to accept or reject the connection. This option is available for internal network topologies (such as testing).
The HTTPS—HTTP Server and Client with SSL 3.0 feature also provides an optional command (ip http secure-client-auth) that, when enabled, has the HTTPS server request an X.509v3 certificate from the client. Authenticating the client provides more security than server authentication by itself.
For additional information on certificate authorities, see the "Configuring Certification Authority Interoperability" chapter in the Cisco IOS Security Configuration Guide.
CipherSuites
A CipherSuite specifies the encryption algorithm and digest algorithm to use on an SSL connection. Web browsers offer a list of supported CipherSuites when connecting to the HTTPS server, and the client and server will negotiate the best encryption algorithm to use from those that are supported by both. For example, Netscape Communicator 4.76 supports U.S. security with RSA Public Key Cryptography, MD2, MD5, RC2-CBC, RC4, DES-CBC, and DES-EDE3-CBC.
For the best possible encryption, you should use a browser that supports 128-bit encryption, such as Microsoft Internet Explorer version 5.5 (or later), or Netscape Communicator version 4.76 (or later). The SSL_RSA_WITH_DES_CBC_SHA CipherSuite provides less security than the other CipherSuites, because it does not offer 128-bit encryption.
In terms of router processing load (speed), the following list ranks the CipherSuites from fastest to slowest (slightly more processing time is required for the more secure and more complex CipherSuites):
1. SSL_RSA_WITH_DES_CBC_SHA
2. SSL_RSA_WITH_RC4_128_MD5
3. SSL_RSA_WITH_RC4_128_SHA
4. SSL_RSA_WITH_3DES_EDE_CBC_SHA
How to Configure the HTTPS—HTTP Server and Client with SSL 3.0
To configure the HTTPS—HTTP Server and Client with SSL 3.0 feature, complete the procedures in the following sections:
•Declaring a Certificate Authority Trustpoint
•Configuring the HTTPS Server with SSL 3.0
•Providing Additional Security and Efficiency
•Configuring the HTTPS Client with SSL 3.0
Declaring a Certificate Authority Trustpoint
Configuring a CA trustpoint is highly recommended for secure HTTP connections. The certified X.509v3 certificate for the secure HTTP server (or client) is obtained from the specified CA trustpoint. If you do not declare a CA trustpoint, then a self-signed certificate will be used for secure HTTP connections. The self-signed certificate is generated automatically.
SUMMARY STEPS
1. enable
2. configure terminal
3. hostname name
4. ip domain-name name ip domain name
5. crypto key generate rsa usage-keys
6. crypto ca trustpoint name
7. enrollment url url
8. enrollment http-proxy host-name port-number
9. crl {query url | optional | best-effort}
10. primary
11. exit
12. crypto ca authenticate name
13. crypto ca enrollment name
14. copy running-config startup-config
or
copy system:running-config nvram:startup-config
DETAILED STEPS
Configuring the HTTPS Server with SSL 3.0
To disable the standard HTTP server and configure the HTTPS server with SSL 3.0, complete the procedure in this section.
Prerequisites
If a certificate authority is to be used for certification, you should declare the CA trustpoint on the routing device before enabling the secure HTTP server.
SUMMARY STEPS
1. enable
2. show ip http server status
3. configure terminal
4. no ip http server
5. ip http secure-server
6. ip http secure-port port-number
7. ip http secure-ciphersuite [3des-ede-cbc-sha] [rc4-128-sha] [rc4-128-md5] [des-cbc-sha]
8. ip http secure-client-auth
9. ip http secure-trustpoint name
10. end
11. show ip http server secure status
DETAILED STEPS
Verifying the Configuration of the HTTPS Server
To verify the configuration of the HTTPS server, connect to the router running the HTTPS server with a web browser by entering https://url, where url is the IP address or hostname of the router. Successful connection using the https prefix (instead of the standard http) indicates that the HTTPS server is configured properly. If a port other than the default port is configured (using the ip http secure-port command), you must also specify the port number after the URL. For example:
https://209.165.202.129:1026
or
https://host.domain.com:1026
Generally, you can verify that the HTTPS server is configured and that you have a secure connection by locating an image of a padlock at the bottom of your browser window. Also note that secure HTTP connections have a URL that starts with "https:" instead of "http:".
Providing Additional Security and Efficiency
The configuration of the standard HTTP server applies to the secure HTTP server as well. To provide additional security and efficiency to both the standard HTTP server and the HTTPS server, complete the procedure in this section.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip http path path-name
4. ip http access-class access-list-number
5. ip http max-connections value
6. ip http timeout-policy idle seconds life seconds requests value
DETAILED STEPS
Configuring the HTTPS Client with SSL 3.0
To configure the HTTPS client with SSL 3.0, complete the procedure in this section.
Prerequisites
The standard HTTP client and the secure HTTP client are always enabled.
A certificate authority is required for secure HTTP client certification; the following steps assume that you have previously declared a CA trustpoint on the routing device. If a CA trustpoint is not configured, and the remote HTTPS server requires client authentication, connections to the secure HTTP client will fail.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip http client secure-trustpoint trustpoint-name
4. ip http client secure-ciphersuite [3des-ede-cbc-sha] [rc4-128-sha] [rc4-128-md5] [des-cbc-sha]
5. end
6. show ip http client secure status
DETAILED STEPS
Configuration Examples for the HTTPS—HTTP Server and Client with SSL 3.0 feature
The following example shows a configuration session in which the secure HTTP server is enabled, the port for the secure HTTP server is configured as 1025, and the remote CA trustpoint server "CA-trust-local" is used for certification.
Router# show ip http server status
HTTP server status: Disabled
HTTP server port: 80
HTTP server authentication method: enable
HTTP server access class: 0
HTTP server base path:
Maximum number of concurrent server connections allowed: 5
Server idle time-out: 600 seconds
Server life time-out: 600 seconds
Maximum number of requests allowed on a connection: 1
HTTP secure server capability: Present
HTTP secure server status: Disabled
HTTP secure server port: 443
HTTP secure server ciphersuite: 3des-ede-cbc-sha des-cbc-sha rc4-128-md5 rc4-12a
HTTP secure server client authentication: Disabled
HTTP secure server trustpoint:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# ip http secure-server
Router(config)# ip http client secure-trustpoint CA-trust-local
Router(config)# ip http secure-port 1024
Invalid secure port value.
Router(config)# ip http secure-port 1025
Router(config)# ip http secure-ciphersuite rc4-128-sha rc4-128-md5
Router(config)# end
Router# show ip http server secure status
HTTP secure server status: Enabled
HTTP secure server port: 1025
HTTP secure server ciphersuite: rc4-128-md5 rc4-128-sha
HTTP secure server client authentication: Disabled
HTTP secure server trustpoint: CA-trust-local
In the following example, the CA trustpoint CA-trust-local is specified, and the HTTPS client is configured to use this trustpoint for client authentication requests:
Router# config terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# crypto ca trustpoint CA-trust-local
Router(ca-trustpoint)# enrollment url http://example.com
Router(ca-trustpoint)# crl query ldap://example.com
Router(ca-trustpoint)# primary
Router(ca-trustpoint)# exit
Router(config)# ip http client secure-trustpoint CA-trust-local
Router(config)# end
Router# copy running-config startup-config
Additional References
The following sections provide references related to the HTTPS—HTTP Server and Client with SSL 3.0 feature.
Related Documents
Standards
|
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No new or modified standards are supported by this feature. |
— |
Related MIBs
Related RFCs
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RFC 2616 |
Cisco's implementation of HTTP is based on RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1. |
Technical Assistance
Feature Information for HTTPS—HTTP Server and Client with SSL 3.0
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.
Glossary
RSA—RSA is a widely used Internet encryption and authentication system that uses public and private keys for encryption and decryption. The RSA algorithm was invented in 1978 by Ron Rivest, Adi Shamir, and Leonard Adleman. The abbreviation RSA comes from the first letter of the last names of the three original developers. The RSA algorithm is included in many applications, such as the web browsers from Microsoft and Netscape. The RSA encryption system is owned by RSA Security.
SHA—The Secure Hash Algorithm. SHA was developed by NIST and is specified in the Secure Hash Standard (SHS, FIPS 180). Often used as an alternative to Digest 5 algorithm.
signatures, digital—In the context of SSL, "signing" means to encrypt with a private key. In digital signing, one-way hash functions are used as input for a signing algorithm. In RSA signing, a 36-byte structure of two hashes (one SHA and one MD5) is signed (encrypted with the private key).
SSL 3.0—Secure Socket Layer version 3.0. SSL is a security protocol that provides communications privacy over the Internet. The protocol allows client and server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. SSL uses a program layer located between the Internet's HTTP and TCP layers. SSL is included as part of most web server products and as part of most Internet browsers. The SSL 3.0 specification can be found at http://home.netscape.com/eng/ssl3/.