mac pro 2007 server 10.6.8 copying files off permissions issue

Ok here goes:

my knowledge: beginner to intermediate.

Gear:

1) Running Mac Pro 2007 as a server

Running Mac OSX 10.6.8

4 hard drives inside set up as RAID (Can't remember what kind but not really important)

2) iMac Running OSX Yosemite 10.10.5

3) Synology NAS DS415+

Synopsis: Mac Pro is dying, I estimate hardware fault. I am consigning it to the dust bin but need to get all my data off before I toss it. Thankfully I can still see it on the network.

Mac Pro 2007 Symptoms:

Bad: Spinning colour wheel on black screen (For hours..days..), after clearing Grey Screen spinning wheel.

Good: I can see it on the network and access files as normal, BUT no share screen (share screen shows same spinning wheel)

What I am trying to do:

I am trying to copy 3.5TB worth of files off the server to a Synology NAS, via another iMac over LAN. (Remember I can't actually login to the Mac Pro normally.)

When I drag and drop using my iMac (after some processing) it tells me I don't have permission to copy all the files.

I would rather get all the files off in one piece if I can.

Question:

A) Can I ssh into the Mac Pro and fix the permissions

or

B) login to the Mac Pro using some kind of terminal access on the Synology NAS to just copy the files directly to the NAS using some Mac OS X super user that won't hang up on the permissions issue?

Help?