Using the PicLan-IP Web Server with SSL
May 30, 1998
This document is very preliminary in nature. Of the techniques discussed
here, the only "supported" method is to use the REDIR.EXE program
to redirect CGI output from IIS.
Modular Software is working on a number of solutions to allow users to run
secure web sites using PicLan-IP. These solutions should allow users to
deploy secure web sites with minimal expense and good performance while maintaining
the ease of deployment and programming of the PicLan-IP product.
The SSL "Road Map" for PicLan-IP
Modular Software will be introducing a number of enhancements to the PicLan-IP
product to allow secure transactions. These enhancements are being
released in steps to provide the maximum benefit to our customers while
maintaining the feature set of the PicLan-IP product suite.
The first SSL enabling enhancement to be released is an SSL "redirector"
that allows PicLan-IP to sit behind an SSL enabled server. Initially,
this redirector is being implemented as a Win32 application that runs using
CGI. We are testing this redirector with Microsoft Internet Information
Server (IIS) version 4.0, but it's design is such that it should work with
most Windows NT/95 web servers that support CGI. The PicLan-IP redirector
should be available starting next week.
After the CGI based redirector has been released, Modular Software will
be looking at higher-performance and more tightly integrated solutions.
The solutions being investigated include:
It should be noted that each of these approaches provides only marginal
performance and almost no functionality gains over the simple PicLan-IP
SSL CGI redirector.
- Integrating SSL directly into PicLan-IP using license RSA algorithms
- Integrating SSL directly into PicLan-IP using Microsoft's "crypto API".
This approach only works on Win32 platforms.
- Integrating SSL directly into PicLan-IP using RSA algorithms after RSA's
patents expire next year
- Integrating the PicLan-IP SSL web redirector using ISAPI and/or NSAPI to
- Integrating a redirector layer for use with Secure/Apache on Linux and perhaps
- Building integration layers for use with SSL capable reverse proxy servers
such as Microsoft Proxy Server and Secure/Apache/Squib
The PicLan-IP SSL CGI Redirector
Traditional web servers support the ability to call application programs
(either executables or scripts) through an interface called the Common
Gateway Interface or CGI. The PicLan-IP SSL Redirector is a small
Win32 application that when called by a traditional SSL enabled web server
will redirect that call to a PicLan-IP web server over a non-encrypted
HTTP connection. This allows you to run PicLan-IP web application
that are secure over the internet even though PicLan-IP does not directly
Is this really secure?
The first question that may come to mind is if this configuration is really
secure. The answer is yes provided that you insure several elements:
The first issue is very easy to accomplish. You can either:
You must be in physical control of the connection between the secure web
server and the PicLan-IP web server. This means that you should not
use a secure web server that is located elsewhere on the internet.
You must insure that the secure portions of your MultiValue application
running on PicLan-IP only accepts connections from the secure web server's
redirector and requires that these connections are encrypted.
The second issue is also easy to accomplish using items that the PicLan-IP
SSL redirector provide:
Run the secure web server and PicLan-IP (in the case of NT hosted MultiValue
platforms) on the same host.
Run the secure web server and PicLan-IP on a single ethernet or fast ethernet
segment that does not have "breachable" hosts that could potentially "packet
sniff" the network wire.
The possibility of someone breaching a local host for the purposes of packet-sniffing
the local network is actually very difficult and unlikely. In any
case, directly hacking into the MultiValue host is probably easier in most
You must insure that secure transactions come only from the IP address
of the secure web server.
You check this information by looking at the ST$RIP address in your web
This address cannot be "spoofed" by the client and is always the actual
connection end-point of the HTTP TCP/IP steam.
You should insure that the connection to the external server is encrypted
by looking at the HTTPS server fields that the redirector supplies:
HTTPS_KEYSIZE - 40 or 128 indicating the level of stream encryption
HTTPS_SECRETKEYSIZE - usually 1024 indicating the size of the public/private
HTTPS_SERVER_ISSUER - Information about who issues the servers certificate
HTTPS_SERVER_SUBJECT - Information about who is using the server certificate
SERVER_PORT_SECURE - 1 indicating a secure connection
Configuring the PicLan-IP SSL Redirector
What you need to do with IIS.
The first step is to setup IIS for secure communications. This involves
not only setting up IIS keys, but also getting a certificate from a public
certificate authority like Verisign or Thawte. More information about
setting up IIS for this purpose is the topic of another document that will
be available in the near future.
After IIS is setup and will accept secure connections, you must make
the PicLan-IP redirector program an executable program within a virtual
directory of the IIS director structure. The recommended proceedure
is to create a directory named /PICLAN-IP/ that points to a directory
on the 'C' drive named c:\plip-rdr\. You will need to give
this directory execute priviledges.
After you setup the c:\plip-rdr\ directory, you will need to copy the
REDIR.EXE program into it. If you wish
you can rename this program when you copy it and there are even some scenarios
where you might want to place multiple copies into the target directory.
Configuring the REDIR.EXE Program
The REDIR.EXE program is controlled by registry entries. You
need to run the REGEDIT program and create a new set of keys called:
Under this registry root, you can create any number of redirection rules.
Each redirection rule consists of a string value with a key name of:
With the example given here, you would create a key with a name of:
This assumes that the secure server is running on 188.8.131.52 and on
port 443 (the default for HTTPS). It is possible to redirect non-secure
(http) connections, but this serves no purpose as PicLan-IP is much more
efficient at servicing these requests directly.
When a request is encountered, the value of the registry key controls
where the REDIR.EXE program will redirect this to. The format
of this value is:
In this case, you would want to configure this as:
This will cause HTTPS requests for:
to be redirected to:
You should then place your secure application in the /secure/app/ subdirectory
Configuring your Application for SSL
Once you have redirected an SSL server to your application, you still need
to be sure that the SSL redirection is actually used. You do this
by including mv/BASIC code in your application that verifies:
When you configure SSL applications, you need to consider ways of optimizing
The ST$RIP field contains the IP address of the SSL server (or servers)
The HTTPS_... header fields contain adequate encryption values (such as
128 bit for bank transactions)
For these reasons, you should be careful to:
SSL connections are much slower than non-SSL connections
The CPU overhead of SSL on a web server can be severe.
Only use SSL for pages that actually contain sensitive data
- You must use SSL for in-line images on a page even if the image itself
is not sensitive. Most browsers require that all documents on a page transfer
over a secure connection if the main document is secure.
- Do not use SSL for pages that do not actually contain live sensitive
data even if they are a part of an application that has some sensitive pages.