Umm… wow.
Apparently I have to use a complete sentence before I can post.
Wouldn’t that effectively have made their intranet an internal internet?
Not if they’re all on the same network.
Spare a thought for the poor sod who have to sort that spaghetti mess out.
Upgrade that mess? Nope. With a side-dish of ‘No way’.
Best solution is a “nuke and pave” with a properly designed infrastructure including all the required bells and whistles. Not a byte more.
“… I’m sorry sir, but after careful investigation of your system we’ve determined that it cannot be unfucked. It is properly fucked now and we can see no way to unfuck it. None. We can give you a new and workable system, but it will not be a product of the current system.”
Agreed fully with the two above statements.
Best will be to nuke it and start clean, and do it properly.