Many of my clients are in engineering or manufacturing and have Unix business management software sitting on a Unix server. The PC's use terminal emulation software to access the application. These machines have vendors to support them and those vendors often use modems hanging off the Unix box to install updates or provide maintenance and repairs. But the Unix guys started to complain about their lowly status of modem user when they found out that the client had a T1 Internet line. So they want Telnet access to their Unix box from the Internet. In ISA Server Publishing is the way to accomplish this.
Here's how you do it:
In ISA Manager, right click on Server publishing and create a new rule. Give the rule a name and makes sense to you and click the enable box. On the next tab enter the IP address of the Unix server as the Internal Server, then browse for the external IP address of your SBS server as the External Address of ISA Server, select Telnet Server for the Mapped Server protocol. Click OK.
This may be silly, but I also used one of our block of 5 static IP addresses and in the router directed it to the same place as the SBS server and gave that second IP address to the UNIX support guys. They may not be fooled but I told them that this IP address went directly to their server. I figure that this way I can easily cut them off, if I need to.
Voila. Now any requests that come in for a Telnet server get redirected to the Unix box. Setup the same thing if they want FTP to their box too only choose the proper protocol at the end.