If you want to use Secure Sockets Layer (SSL) support in your AS/400 Telnet server to create secure encrypted sessions between Telnet clients and your AS/400, you may be interested in a new IBM OS/400 PTF upgrade that was scheduled for release on May 31. This upgrade extends AS/400 Telnet capabilities to provide SSL client authentication support in addition to the server authentication support included in the base release of OS/400 V4R4. The upgrade is available through PTF SF61406 for OS/400 V4R4 only, and it will be included in the base support of the new OS/400 V4R5, which is expected soon.
Explaining It in English
To understand what this means, you must understand how AS/400 sessions are created for Telnet clients. Telnet clients start individual sessions by attaching to the AS/400 Telnet server. Telnet is one of the base TCP/IP protocols, and it provides remote terminal emulation over the Internet. As IBM improves TCP/IP Telnet access, it adds PTF changes to the Telnet server on the AS/400 and then includes those changes in the base functionality of the next OS/400 release, as were seeing here. The Telnet client vendors, in turn, modify their packages to exploit the new functionality. The most famous of these Telnet server enhancements occurred in 1998, when IBM added the ability to use unique workstation IDs instead of OS/400-generated device names. Other enhancements have been added as additional functionality has been needed.
In OS/400 V4R4, IBM provided SSL support for Telnet clients. For the Telnet server, this meant that clients could establish secure SSL sessions with an AS/400. To create an SSL-enabled session, your PCs and AS/400 always require the following components:
A scheme for authentication so that the computers involved in the SSL session can verify each others identity. There are two types of authentication: server authentication (where the client verifies that this is the correct server host to attach to) and client authentication (where the server verifies that the incoming client is approved to access the servers data and services).
A method for encryption of data and requests that pass between the client and the host server (the AS/400, in this case).
Authentication can be performed in SSL by creating digital certificates on your AS/400 and PC and then enabling both machines to use SSL. Please note that the actual process is a little more complicated, but, for the purposes of this article, this simplified explanation suffices.
When IBM added SSL to AS/400 Telnet, it only implemented server authentication, not client authentication. Server authentication is beneficial in an e-business environment, such as an online store, where the client wants to make sure that the attached server is the intended host before it provides sensitive information, such as a credit card number. There is no client authentication included in the base release of OS/400 V4R4, so you can only authenticate the servers identity to the SSL client.
Why Client Authentication?
As opposed to server authentication, client authentication assures the server that the client is authorized to use its services. Client authentication could also be used in an e-business environment to assure the server application that the client is cleared to access secured data on the server, such as order status. You can also use SSL client authentication to lock down your AS/400 to specified Telnet users who have the proper digital certificates. Client authentication completes the equation for AS/400 Telnet SSL so that both sides can be confident in the transaction.
PTF SF61406 will add this capability to your AS/400 Telnet SSL configuration, and the PTF should be available now. This upgrade will allow you to toggle AS/400 Telnet client authentication on and off by using a service program. When SSL client authentication is set on, the AS/400 Telnet server authenticates client certificates for any client connecting through the SSL-designated TCP/IP port. It rejects any client that doesnt send a valid client certificate when connecting. According to IBM, you can subject all of your SSL- enabled users to authentication while letting your other users (who are coming in through a non-SSL port) access your AS/400 without an approved digital certificate.
To Find Out More
This support is explained on the AS/400 Telnet ServerSSL Client Authentication Web page (www.as400.ibm.com/tcpip/telnet/ ssl.htm). On this page, IBM shows how to set up client authentication using AS/400 Telnet server and SecureWay Host On-Demand 4.03. If youre using a different Telnet client, check with your vendor to see how to configure that package for SSL client authentication.
IBM also offers several links on this page to other locations that explain what AS/400 Licensed Program Products you need to order, install, and use SSL on your AS/400; to configure SSL on your AS/400; and to troubleshoot an SSL-enabled Telnet server.
If youre using SSL for a secure AS/400 e-business server or for dedicated access over the Internet, check out this OS/400 PTF upgrade. In the right situation, client authentication can add many new capabilities to your SSL sessions.
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