This isn't a support request as I figured out how to solve the problem I ran into. Hopefully this will help others.
I just installed Endian Firewall 2.2 Beta 2 after having run for a few months with no problems. The installation went just fine (after I used a CD-R rather than a CD-RW for the CD), but I couldn't access the web interface to complete the installation. I went back to the server and found that, although Endian said I was supposed to have the address I specified for GREEN, the GREEN interface didn't have an IP Address assigned to it. I found this by running ifconfig.
The solution? Run
ifconfig eth0 172.16.x.x netmask 255.255.0.0
Obviously you should use the correct parameters for your own network.
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Chris